ORCID Profile
0000-0002-5213-3978
Current Organisations
University of Adelaide
,
University of Adelaide Roseworthy Campus
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Genetics and Molecular Research
Date: 2011
Abstract: Two analyses, cubic and piecewise random regression, were conducted to model growth of crossbred cattle from birth to about two years of age, investigating the ability of a piecewise procedure to fit growth traits without the complications of the cubic model. During a four-year period (1994-1997) of the Australian "Southern Crossbreeding Project", mature Hereford cows (N = 581) were mated to 97 sires of Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon, and Wagyu breeds, resulting in 1141 steers and heifers born over four years. Data included 13 (for steers) and eight (for heifers) live body weight measurements, made approximately every 50 days from birth until slaughter. The mixed model included fixed effects of sex, sire breed, age (linear, quadratic and cubic), and their interactions between sex and sire breed with age. Random effects were sire, dam, management (birth location, year, post-weaning groups), and permanent environmental effects and for each of these when possible, their interactions with linear, quadratic and cubic growth. In both models, body weights of all breeds increased over pre-weaning period, held fairly steady (slightly flattening) over the dry season then increased again towards the end of the feedlot period. The number of estimated parameters for the cubic model was 22 while for the piecewise model it was 32. It was concluded that the piecewise model was very similar to the cubic model in the fit to the data with the piecewise model being marginally better. The piecewise model seems to fit the data better at the end of the growth period.
Publisher: CSIRO Publishing
Date: 14-03-2023
DOI: 10.1071/AN22458
Abstract: Context Commercial beef and sheep producers have adopted using condition score for management of cows and ewes to maximise productivity. Significant premiums are being paid for bulls and rams with higher-fat breeding values based on young animal measurements, with the aim of increased resilience in adult female progeny. Aims The aim of this study was to quantify the relationship between adult body condition score and young muscle and fat and also the genetic variation in condition that is independent of yearling traits. Methods Published genetic parameters for four large data sets from Angus and tropically adapted cattle, and composite and Merino sheep were used to partition genetic variation in adult condition that is associated with, or independent of, young composition measures. Key results One genetic standard deviation in young muscle or fat was associated with approximately just 0.1 adult body condition scores. Approximately ¾ of the genetic variation in adult body condition score (BCS) is independent of genetic variation in young weight and composition traits. Conclusions and implications Producers need to be careful with premiums paid for bulls and rams with superior yearling composition traits with the aim of changing adult BCS. The best way to achieve this is for seedstock breeders to record and report breeding values for cow and ewe BCS.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13060
Abstract: Seedstock breeders’ perspectives on topics associated with maternal productivity in beef cattle were investigated through the use of qualitative in-depth semi-structured interviews. Given the complexity of maternal productivity, it is possible that some issues may not be fully captured by recording performance and data analysis. This paper discusses theory emerging from content analysis of interview data on management and genetic factors affecting maternal productivity as detailed by seedstock breeders in southern Australia. Overall, 24 interviews were conducted as part of an intensive field-work component with seedstock breeders involved with the Cooperative Research Centre for Beef Genetic Technologies’ Maternal Productivity Project. Qualitative content analysis of interview data revealed a considerable ergence in attitudes to cow management with regards to grazing management, body condition fluctuation and the utilisation of body fat reserves. Specifically, production systems erged on the basis of animal management characterised by either ‘controlled’ or ‘variable input’ feeding strategies. Variation in management approach was associated with different perspectives on the perceived importance of selecting for production traits including growth, beef yield and milk compared with selection for perceived resilience traits including increased subcutaneous fat. The results demonstrated that among seedstock breeders targeting similar end markets, substantial variation in animal selection and management exists and this requires further characterisation to ensure breeding programs and animal management are optimal.
Publisher: Wiley
Date: 03-2009
Publisher: Wiley
Date: 20-10-2014
DOI: 10.1002/JBMR.2263
Abstract: Parent-of-origin-dependent (epi)genetic factors are important determinants of prenatal development that program adult phenotype. However, data on magnitude and specificity of maternal and paternal genome effects on fetal bone are lacking. We used an outbred bovine model to dissect and quantify effects of parental genomes, fetal sex, and nongenetic maternal effects on the fetal skeleton and analyzed phenotypic and molecular relationships between fetal muscle and bone. Analysis of 51 bone morphometric and weight parameters from 72 fetuses recovered at day 153 gestation (54% term) identified six principal components (PC1-6) that explained 80% of the variation in skeletal parameters. Parental genomes accounted for most of the variation in bone wet weight (PC1, 72.1%), limb ossification (PC2, 99.8%), flat bone size (PC4, 99.7%), and axial skeletal growth (PC5, 96.9%). Limb length showed lesser effects of parental genomes (PC3, 40.8%) and a significant nongenetic maternal effect (gestational weight gain, 29%). Fetal sex affected bone wet weight (PC1, p < 0.0001) and limb length (PC3, p < 0.05). Partitioning of variation explained by parental genomes revealed strong maternal genome effects on bone wet weight (74.1%, p < 0.0001) and axial skeletal growth (93.5%, p < 0.001), whereas paternal genome controlled limb ossification (95.1%, p < 0.0001). Histomorphometric data revealed strong maternal genome effects on growth plate height (98.6%, p < 0.0001) and trabecular thickness (85.5%, p < 0.0001) in distal femur. Parental genome effects on fetal bone were mirrored by maternal genome effects on fetal serum 25-hydroxyvitamin D (96.9%, p < 0.001) and paternal genome effects on alkaline phosphatase (90.0%, p < 0.001) and their correlations with maternally controlled bone wet weight and paternally controlled limb ossification, respectively. Bone wet weight and flat bone size correlated positively with muscle weight (r = 0.84 and 0.77, p < 0.0001) and negatively with muscle H19 expression (r = -0.34 and -0.31, p < 0.01). Because imprinted maternally expressed H19 regulates growth factors by miRNA interference, this suggests muscle-bone interaction via epigenetic factors.
Publisher: Genetics and Molecular Research
Date: 2011
Abstract: A joint growth-carcass model using random regression was used to estimate the (co)variance components of beef cattle body weights and carcass quality traits and correlations between them. During a four-year period (1994-1997) of the Australian "southern crossbreeding project", mature Hereford cows (N = 581) were mated to 97 sires of Jersey, Wagyu, Angus, Hereford, South Devon, Limousin, and Belgian Blue breeds, resulting in 1141 calves. Data included 13 (for steers) and 8 (for heifers) body weight measurements approximately every 50 days from birth until slaughter and four carcass quality traits: hot standard carcass weight, rump fat depth, rib eye muscle area, and intramuscular fat content. The mixed model included fixed effects of sex, sire breed, age (linear, quadratic and cubic), and their interactions between sex and sire breed with age. Random effects were sire, dam, management (birth location, year, post-weaning groups), and permanent environmental effects, and their interactions with linear, quadratic and cubic growth, when possible. Phenotypic, sire and dam correlations between body weights and hot standard carcass weight and rib eye muscle area were positive and moderate to high from birth to feedlot period. Management variation accounted for the largest proportion of total variation in both growth and carcass traits. Management correlations between carcass traits were high, except between rump fat depth and intramuscular fat (r = 0.26). Management correlations between body weight and carcass traits during the pre-weaning period were positive except for intramuscular fat. The correlations were low from birth to weaning, then increased dramatically and were high during the feedlot period.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN14797
Abstract: The productivity of 500 Angus cows, ergently selected for either rib fat or residual feed intake (RFI) based on BREEDPLAN estimated breeding values (EBVs) and managed under two levels of nutrition (stocking rates), was evaluated. The study examined the effects of genetic line, nutrition and weaning history on profiles for weight, rib fat depth, fatness (rib fat depth adjusted for weight) and supplementary feed requirements from just before the first joining as heifers through to the weaning of their third calf. Cows gained both weight and fat as they grew older. Observed fluctuations in weight and rib fat depth, within each year, were associated with pasture availability and physiological demands. Cows that did not wean a calf in a given year became heavier and fatter than cows that did and they remained so when they calved the following year. High-fat and High-RFI were always fatter and lighter than Low-fat and Low-RFI cows, respectively. The difference in rib fat and fatness between High- and Low-RFI lines (P 0.001) was similar to, although slightly greater than, the difference between High- and Low-fat lines (P = 0.048) reflecting differences in rib fat EBVs between High-RFI (3.2 ± 1.47) and Low-RFI (–0.7 ± 1.3) compared with High-fat (1.1 ± 0.78) and Low-fat (–1.4 ± 0.67). Cows on High-Nutrition were heavier and fatter than those on Low-Nutrition (P 0.001) but there were no significant interactions between genetic line and nutrition (P 0.05). Supplementary feeding threshold was reached earlier by Low-fat and Low-RFI cows than their counterparts. Calculations based on the data in the present paper estimate that if cows lose condition at a rapid rate (1 condition score/month), then a cow with an extra 1 mm rib fat EBV would take 7.5 days longer to reach the same supplementary feeding threshold. Fat EBVs can, therefore, be a useful tool in assisting beef producers to match genotype to their production system.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13065
Abstract: Growth, feed intake, feed efficiency, and carcass and meat quality characteristics of 136 Angus steers differing in genetic merit for post-weaning residual feed intake (RFIp) were measured over 251 days in a large commercial feedlot. The steers were evaluated in two groups, low (Low-RFI) and high (High-RFI) genetic RFIp, measured by estimated breeding values for RFIp (RFIp-EBV). The difference in RFIp-EBV between the Low- and High-RFI groups was 1.05 kg/day (–0.44 vs 0.61 kg/day P 0.05). The Low- and High-RFI steers were similar (P 0.05) in age (445 vs 444 days) and weight (435 vs 429 kg) at induction, and at the end of the feeding period (705 vs 691 kg). Average daily gain (ADG) over 251 days had a small negative association with variation in RFIp-EBV (P 0.05), reflecting a 3.6% greater ADG accompanying a difference of 1 kg/day in RFIp-EBV. Pen feed intake and feed conversion by the Low-RFI group were 10.4 kg/day and 9.3 kg/kg, and for the High-RFI group were 11.1 kg/day and 10.4 kg/kg, but without availability of in idual animal feed-intake data it was not possible to test for significant differences. Carcass weight and dressing-percentage was similar for the Low- and High-RFI steers. High-RFI steers had a significantly (P 0.05) greater depth of subcutaneous rib fat at induction and finished with 5 mm more (P 0.05) fat at the 10/11th ribs on the carcass than the Low-RFI steers. Cross-sectional area of the eye-muscle and three measures of intramuscular or marbling fat did not differ (P 0.05) between the Low- and High-RFI steers. Shear force was higher (P 0.05) in meat s les aged for 1 day from the Low-RFI steers, but there was no difference (P 0.05) from the High-RFI steers after 7 days of ageing. Compression values for meat s les aged for 1 day did not differ between the RFI groups but were higher in meat s les aged for 7 days from the Low-RFI steers. For these Angus steers, genetic superiority in RFI was associated phenotypically with superior weight gain, decreased rib fat depth, slightly less tender meat, and no compromise in marbling fat or other carcass and meat quality traits.
Publisher: Springer Science and Business Media LLC
Date: 02-08-2006
DOI: 10.1007/S00122-006-0333-Z
Abstract: A statistical approach is presented for selection of best performing lines for commercial release and best parents for future breeding programs from standard agronomic trials. The method involves the partitioning of the genetic effect of a line into additive and non-additive effects using pedigree based inter-line relationships, in a similar manner to that used in animal breeding. A difference is the ability to estimate non-additive effects. Line performance can be assessed by an overall genetic line effect with greater accuracy than when ignoring pedigree information and the additive effects are predicted breeding values. A generalized definition of heritability is developed to account for the complex models presented.
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.MEATSCI.2017.11.024
Abstract: Twenty Angus steers were fed a diet low in β-carotene and vitamin A for 10months. Ten steers were supplemented with vitamin A weekly, while the other ten steers did not receive any additional vitamin A. The results demonstrated that the restriction of vitamin A intake increased intramuscular fat (IMF) by 46%. This was a function of the total number of marbling flecks increasing by 22% and the average marbling fleck size increasing by 14%. Vitamin A restriction resulted in marbling flecks that were less branched (22%) and slightly more round (4%) with an increased minor axis length (7%). However, restricting vitamin A did not affect the size of the intramuscular or subcutaneous adipocyte cells or the subcutaneous fat depth. The results suggest that vitamin A affects the amount of marbling and other attributes of the marbling flecks due to hyperplasia rather than hypertrophy. This may explain why vitamin A restriction specifically affects IMF rather than subcutaneous fat deposition.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN15601
Abstract: The objective of the present study was to evaluate the effect of including a pellet containing feed components targeted at methane-producing microbes and methane-producing biochemical pathways, into the ration of beef cattle in southern Australia. The so-called ‘methane-reducing supplement’ (MRS) components were chosen from readily available and inexpensive sources to ensure high adoption of the practice if successful. The effect of the pellet on animal performance, diet DM digestibility and gas emissions (measured using an open-circuit gas quantification system) of beef cattle in comparison with animals fed a control diet or high-quality supplement (HQS) was evaluated. In the first trial, there were no differences in DM and digestible energy (DE) intake, but the methane emission in g/day, g/MJ of DE intake (P 0.01), and in g/kg of DM intake (P = 0.01) were lower for steers fed MRS. There was also a trend to lower carbon dioxide emission (g/MJ of DE intake) in steers fed MRS (P = 0.07). In the second trial, heifers fed the MRS produced 18.7% less carbon dioxide (P 0.01) and 15.5% less methane (P = 0.01) than heifers on the HQS supplement, when expressed in g per unit supplement intake on a bodyweight basis. There was no difference in growth rate of heifers on the HQS and MRS supplements. Combining methane-inhibiting feedstuffs derived from agro-industrial by-products into supplements for cattle in southern Australia appears to be an effective means of reducing methane output and methane intensity from grazing beef cattle.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN14594
Abstract: The present study determined the impact of maternal genetics for estimated breeding values for rib fat (High-Fat, Low-Fat) or residual feed intake (RFI High-RFI, Low-RFI) on the carcass compliance of Angus steer progeny when reared pre-weaning under High or Low-Nutrition and post-weaning under various finishing system (grazing versus short-term feedlot). The dams were joined to sires of similar genetic background (close to average estimated breeding values) and sires were rotated among all dam genotypes, with herds located at either Struan Research Centre, near Naracoorte in the south-east of South Australia, or Vasse Research Station, in the south-west of Western Australia. The breeding herd was part of the Beef CRC maternal productivity project and cows were managed under either High or Low-Nutrition, achieved by adjustments to stocking rate in rotational grazing systems and supplementary feeding, so as to maintain ~20% difference in cow liveweight. The steer progeny were weaned at ~7 months of age, with in iduals from both pre-weaning nutritional treatments being treated the same from then on at each site. Steers from Struan Research Centre in South Australia born in 2008 and 2009 were sold and grown out on pasture on a local commercial property. Steer calves born in 2010 at Vasse remained on the station where they were backgrounded on hay, followed by a short period (111 days) total mixed ration containing 40% grain. In the first year, steers from Struan (n = 58) were slaughtered together at ~2 years of age, and in the second year (n = 85), consigned to six slaughter groups as their ultrasound-scanned subcutaneous P8 (rump) fat reached 7 mm and their liveweight exceeded 550 kg. Steers from Vasse (n = 101) were slaughtered at ~12 months of age, all on the same day. High-Fat-line dams produced steers with carcasses with greater P8 fat than did Low-Fat-line dams at both sites. At Struan, when the 2008-born steers were slaughtered together, more steers from Low-Fat dams failed to meet minimum fat specifications, than steers from High-Fat dams (28% vs 9% respectively). The steers born in 2009 at Struan all met processor fat specifications but steers from the Low-Fat dams took longer to reach the fat threshold, and so had greater carcass weight, but attracted more price penalties because of increased dentition. All steers from Vasse met minimum requirements for fat, with none penalised for dentition. Vasse steers from High- or Low-RFI dams performed in a manner similar to that from High- and Low-Fat dams, respectively, in that the High-RFI group produced fatter carcasses than did the Low-RFI group. Steers reared under low pre-weaning nutrition weighed less at weaning than did those on High-Nutrition, but had higher weight gains after weaning, although insufficient to result in the same carcass weight. The results showed that commercial cattle producers need to be aware of the balance and trade-off among fat breeding value, effect of pre-weaning nutrition and post-weaning growth required to ensure their cattle meet market specifications and to avoid price penalties.
Publisher: Genetics and Molecular Research
Date: 2011
Abstract: A joint growth-carcass analysis was conducted to develop equations for predicting carcass quality traits associated with variation in growth path of crossbred cattle. During a four-year period (1994-1997) of the Australian "Southern Crossbreeding Project", mature Hereford cows (r = 581) were mated to 97 sires of Jersey, Wagyu, Angus, Hereford, South Devon, Limousin, and Belgian Blue breeds, resulting in 1141 calves. Data included body weight measurements of steers and heifers from birth until slaughter and four carcass quality traits: hot standard carcass weight, rump fat depth, rib eye muscle area, and intramuscular fat content. The model provides nine outputs: median and mean of carcass quality traits, predicted means, and lower and upper confidence intervals, as well as predicted intervals of carcass quality traits (95%) and economic values for domestic market and export markets. Input to the model consists of sex, sire breeds, age (in days)-weight (kg) pairs and slaughter age (500 days for heifer and 700 days for steers). The prediction model is able to accommodate different sexes across seven sire breeds and various management groups at any slaughter age. Its strength lies in its simplicity and flexibility, desirable to accommodate producers with different management schemes. In general, fat depth and intramuscular fat were found to be more affected by differences in growth rate than hot carcass weight and eye muscle area. Also, export market value was more sensitive to growth rate modifications than domestic market value. This model provides a tool by which the producer can estimate the impact of management decisions.
Publisher: Springer Science and Business Media LLC
Date: 11-04-2007
DOI: 10.1007/S00122-007-0515-3
Abstract: A statistical approach for the analysis of multi-environment trials (METs) is presented, in which selection of best performing lines, best parents, and best combination of parents can be determined. The genetic effect of a line is partitioned into additive, dominance and residual non-additive effects. The dominance effects are estimated through the incorporation of the dominance relationship matrix, which is presented under varying levels of inbreeding. A computationally efficient way of fitting dominance effects is presented which partitions dominance effects into between family dominance and within family dominance line effects. The overall approach is applicable to inbred lines, hybrid lines and other general population structures where pedigree information is available.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN14034
Abstract: Cow bodyweight gain, calf weaning weight, feed intake and maternal productivity of 500 Angus cows, in 64 replicate groups, were measured over three parities at two locations (Struan and Vasse) as part of the Beef CRC Maternal Productivity Project. The cows were sourced as heifers from the top and bottom 10% of BREEDPLAN Rib Fat EBV (High-Fat and Low-Fat), and from High and Low residual feed intake (RFI) selection lines (High-RFI and Low-RFI). Each of the four genotypes were run under High- and Low-Nutrition (measured as feed on offer) at both sites. The High-Fat cows were 7% more efficient at producing weaner calves under Low-Nutrition than were the Low-Fat cows. This was driven primarily by the 4% difference between the lines in weaning rate. When weaning rate differences were accounted for (as covariate), there was no difference between the Fat lines in the efficiency of weaner weight production. When the weight gain of the cow was included as an output in addition to calf weaning weight, there was also no difference between the Fat lines in efficiency. Low-RFI cows were always more efficient at producing weaner calves than were the High-RFI cows. This was primarily driven through a 7% reduction in annual feed intake (across both nutrition treatments). However, the Low-RFI cows were leaner, had 6.3% lower weaning rate and calved on average 5.4 days later than did the High-RFI cows. Furthermore, the largest differences in feed intake were in spring when feed availability is greatest. In the context of the results herein, a balanced breeding program should include selection for improved reproduction and low RFI.
Publisher: Elsevier BV
Date: 06-2007
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13218
Abstract: This paper reports a subset of results from the Beef Cooperative Research Centre-funded Maternal Productivity Project. This research aimed to describe the response of Angus cows of different and ergent genotypes to variable nutritional environments over five breeding seasons. Cows selected for a ergence in either fat depth (HFat vs LFat) or residual feed intake (RFI: HRFI vs LRFI) based on mid-parent estimated breeding values (EBV) for those traits were allocated in replicate groups to either high or low nutritional treatments at two different sites, namely the Vasse Research Centre in Western Australia and the Struan Research Centre in South Australia. The traits reported in this paper include output traits (birth and weaning weight of calves, liveweight change of cows), change traits (change in Rib Fat, P8 fat, eye muscle area and liveweight between specified time points) and reproductive traits [pregnancy rates, percentage calves born alive and days to calving at the days to calving at the second calving opportunity (DC2)]. Having had their first calf, the vulnerability of these young cows to nutritional restriction and how it may adversely affect rebreeding was examined. HFat and HRFI cows were fatter, heavier and had greater eye muscle area than LFat and LRFI, respectively, at all times during the breeding cycle on both levels of nutrition. There was no difference in either days-to-calving or pregnancy rates after the second mating between genotypes. Equally, nutritional treatment had no effect on these traits in this cohort of cows. There was evidence for an implied genetic correlation between Rib Fat EBV, DC2 and pregnancy rates of –0.38 that suggests that selection for leanness may result in reduced fertility of the herd but the effect was not significant herein. As long as producers record the phenotype for both traits and select cows with favourable DC2 as well as low fatness, these problems can be avoided, owing to only 22% of variation in pregnancy rates being explained by DC2 and Rib Fat EBV. Producers can largely be confident that selection for leanness, or increased feed efficiency, has little impact on productivity as long as cows are in adequate body condition to remain healthy and productive.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN15636
Abstract: The present paper focuses on the economic evaluation of the observed differences in maternal productivity of different genetic lines in Angus cattle that were managed under contrasting nutritional regimes typical of southern Australia. Five hundred Angus cows were managed concurrently at two locations in southern Australia. On each site, the cows were managed under the following two different nutritional treatments: High and Low, to simulate different stocking rates. Cows selected for a ergence in either carcass rib-fat depth or residual feed intake based on mid-parent estimated breeding values for those traits, were allocated in replicate groups to either High- or Low-nutrition treatments. By design, the supplementary feeding regime was the same for the High and Low genetic lines to ensure genetic differences were not confounded with management differences. Animal productivity results from the experiment were used as input data to evaluate the economic performance of the four genetic lines under the two nutritional treatments. Two methods were used the first was a gross-margin calculation of income minus variable costs as AU$ per breeding cow for a 1000-cow herd the second was a whole-farm linear programming model maximising the gross margin. Stocking rates were optimised by matching the energy requirements for the whole herd with the energy available from pasture and supplementary feed on a representative 700-ha farm. Using the two methods of calculating gross margin (per cow and optimised per hectare), including examination of sensitivity to changes in prices of cattle and supplementary feed, the present study demonstrated that genetically leaner cows due to selection of low fat or low residual feed intake, had gross margins superior to those of genetically fatter cows. They generated more income by selling more liveweight due to heavier weights and higher stocking rates. The results are affected by the management system utilised and some confounding with growth (leaner genetic lines had higher growth estimated breeding values), but will assist producers to make more informed decisions about how to manage animal breeding and nutritional interactions.
Publisher: Cambridge University Press (CUP)
Date: 23-06-2016
DOI: 10.1017/S2040174416000283
Abstract: Intrauterine growth restriction (IUGR) has adverse effects on metabolic health and early life, whereas physical activity is protective against later development of metabolic disease. Relationships between birth weight and physical activity in humans, and effects of IUGR on voluntary activity in rodents, are mixed and few studies have measured physical activity in a free-ranging environment. We hypothesized that induced restriction of placental growth and function (PR) in sheep would decrease spontaneous ambulatory activity (SAA) in free-ranging adolescent and young adult progeny from multi-fetal pregnancies. To test this hypothesis, we used Global Positioning System watches to continuously record SAA between 1800 and 1200 h the following day, twice during a 16-day recording period, in progeny of control (CON, n =5 males, 9 females) and PR pregnancies ( n =9 males, 10 females) as adolescents (30 weeks) and as young adults (43 weeks). PR reduced size at birth overall, but not in survivors included in SAA studies. In adolescents, SAA did not differ between treatments and females were more active than males overall and during the day (each P .001). In adults, daytime SAA was greater in PR than CON females ( P =0.020), with a similar trend in males ( P =0.053) and was greater in females than males ( P =0.016). Adult SAA was negatively correlated with birth weight in females only. Contrary to our hypothesis, restricted placental function and small size at birth did not reduce progeny SAA. The mechanisms for increased daytime SAA in adult female PR and low birth weight sheep require further investigation.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CP14312
Abstract: Variety selection in perennial pasture crops involves identifying best varieties from data collected from multiple harvest times in field trials. For accurate selection, the statistical methods for analysing such data need to account for the spatial and temporal correlation typically present. This paper provides an approach for analysing multi-harvest data from variety selection trials in which there may be a large number of harvest times. Methods are presented for modelling the variety by harvest effects while accounting for the spatial and temporal correlation between observations. These methods provide an improvement in model fit compared to separate analyses for each harvest, and provide insight into variety by harvest interactions. The approach is illustrated using two traits from a lucerne variety selection trial. The proposed method provides variety predictions allowing for the natural sources of variation and correlation in multi-harvest data.
Publisher: CSIRO Publishing
Date: 16-09-2021
DOI: 10.1071/AN21171
Abstract: Context Overseas studies have quantified production differences of Hereford Angus crossbreds compared with purebred Angus for a range of traits including growth, carcass and reproductive traits. Aim This study aimed to quantify breed and heterosis effects using genomics. Methods Thirty Hereford and 30 Angus sires were mated to 1100 Angus cows and heifers in a large commercial herd run on pasture at Musselroe Bay, Tasmania. Approximately 1650 calves were born. Steers (743) were grown for an average of 23 months and then slaughtered. Results Heterozygosity effects were significant for birth, weaning and carcass weight and also loin eye-muscle area. On average, higher-quality (percentile) Hereford than Angus bulls were used. Breeding values were calculated for sires and could be compared with a common base given they also had BREEDPLAN breeding values published. Conclusions When heterozygosity was accounted for and when compared on a common base, progeny of average Angus sires were superior to progeny of Hereford sires for birthweight, carcass weight, eye-muscle area and intramuscular fat. Implications The method of benchmarking breeds using crossbred cattle and genomics provides a model for rapid adoption of multi-breed estimated breeding values, which is desirable for commercial beef producers.
Publisher: CSIRO Publishing
Date: 13-07-2021
DOI: 10.1071/AN21094
Abstract: Context Significant opportunities have been identified in the northern Australian beef industry that can improve efficiency and profitability by using composite or crossbred cattle and genomic selection. The improved performance of composite cattle is partly due to heterosis. One of the major genetic bases of heterosis is dominance. Traditionally, dominance is ignored in genetic evaluation but could improve the accuracy of breeding values and help maintain genetic ersity. Aims The aim of this study is to describe the impact of including a dominance relationship matrix with different parameterisation methods and including heterozygosity fraction on estimated breeding values for 400-day weight in a composite population. Methods Genotype and phenotype data were obtained from 2364 tropical composite animals and were imputed to 27 648 single nucleotide polymorphisms. Genetic parameters and breeding values were estimated for 400-day weight from a linear mixed model using a genomic relationship matrix, heterozygosity fraction and three different parameterisation methods for the dominance relationship matrix, including genotypic, classical and the natural and orthogonal interaction approach. Genetic parameters and breeding values where compared over the three different parameterisation methods. Key results The heritability for all models when heterozygosity was not fitted ranged from 0.25 to 0.35, with the genotypic dominance model having the lowest additive heritability. Including heterozygosity fraction in the model as a fixed covariate resulted in substantial (39–49%) reductions in dominance variance across all models but a minimal change in the additive variance and, therefore, heritability (0.29–0.35). Conclusions and Implications In a composite population, including heterozygosity fraction in the model was important due to directional dominance. When heterozygosity fraction was not included, the genetic variance was incorrectly partitioned, and the dominance estimates were biased. Including the dominance relationship matrix improved the accuracy of breeding values. Parameterisation methods for forming the dominance relationship matrix are largely a matter of what estimates are required from the models and convenience. The additive values were largely independent of dominance parameterisation when heterozygosity was in the model.
Publisher: Science Alert
Date: 15-01-2009
DOI: 10.3923/PJBS.2009.222.230
Abstract: In order to investigate variation in carcass quality traits, during a four-year period, mature Hereford cows (637) were mated to 97 sires from seven breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue), resulting in 1144 calves. Carcass production traits (carcass weight = HCWt, fat depth = P8, eye muscle area = EMA, intramuscular fat = IMF) were obtained from these cattle that constitute the Australia's Southern Crossbreeding Project. Data were analysed using multi-variate sire model containing fixed effects of sex, sire breed, slaughter age nested within sexes. Random effects were sire, dam, management (location-year-post-weaning groups) and environmental effects. HCWt of South Devon, Belgian Blue, Limousin and unexpectedly, Angus were the heaviest on the average. Hereford calves were intermediate and Jersey and Wagyu were lighter on the average than others. Carcasses of the Belgian Blue and Limousin had low P8 and IMF, carcasses of Hereford and South Devon were intermediate and Angus, Jersey and Wagyu had high P8 and IMF. Management group effects were greatest especially for EMA and IMF. The sire variation was about 6, 6, 4 and 2% of total variation for HCWt, P8, EMA and IMF. Heritability ranged from 0.20 to 0.37 (carcass weight). The genetic correlation between the two fat depots was not as high (0.18) as expected. Results from this study suggest that strategies to increase genetic potential for HCWt would increase the genetic potential for EMA but may reduce marbling and tend to slightly increase P8. All phenotypic correlations were positive, although not large.
Publisher: Elsevier BV
Date: 2015
Publisher: CSIRO Publishing
Date: 07-06-2023
DOI: 10.1071/AN22462
Abstract: Context Quantity and quality of both meat and wool are important for selection programs of the dual-purpose Corriedale sheep. In Corriedales, black pigmentation of nose skin and hooves is preferred as part of the breed standard. However, within the breed, pigmentation can vary from none to complete pigmentation. Aims The aim was to discover single-nucleotide polymorphisms (SNPs) and genes associated with nose and hoof pigmentation and to estimate genetic parameters of nose and hoof pigmentation, wool traits and meat traits. Methods The phenotype and genotype data on Corriedale lambs (n = 764) produced from 44 sires (12 studs) and 300 ewes in 2017–2019 were used in this study. Lambs were slaughtered at 6–7 months of age. Nose pigmentation and hoof pigmentation were scored on a five-point scale, where no pigmentation was scored 0 and complete pigmentation was scored 5. Wool- and meat-quality traits were measured, including greasy fleece weight, fibre diameter, weaning weight, hot standard carcass weight and intramuscular fat percentage. The lambs were genotyped with the GGPOvine50K SNP chip. A genome-wide association study (GWAS) was conducted. Genetic parameters and bivariate analyses were estimated using ASReml-R. Results The lambs had a mean nose-pigmentation score of 3.69 and hoof-pigmentation score of 4.12. The nose pigmentation (h2 = 0.58) and hoof pigmentation (h2 = 0.51) were highly heritable and highly correlated (rG = 0.73). The GWAS identified a genome-wide significant SNP (OAR19_33278780.1) associated with nose pigmentation (q-value = 0.04). This SNP is positioned in a known pigmentation gene, melanocyte-inducing transcription factor (MITF). The same SNP was the sixth-most associated SNP for hoof pigmentation but did not reach significance level. OAR19_33278780.1 also had a significant effect on back conformation and weaning weight. Conclusions The results of these analyses have provided information and an understanding of the genetics for pigmentation of nose and hooves in Corriedale sheep. Implications Nose and hoof pigmentation are highly genetically correlated with each other, but with no negative effects on production traits.
Publisher: Elsevier BV
Date: 03-2010
Publisher: Wiley
Date: 05-2003
DOI: 10.1007/S11745-003-1339-7
Abstract: An experiment examined delta9 desaturase activity and FA composition in subcutaneous adipose tissue in two differing breeds of cattle. Jersey-sired cattle had significantly higher rates of desaturase activity than Limousin-sired cattle (1.55 vs. 0.75 nmol/mg protein/min). This difference was also demonstrated by a lower concentration of in idual (e.g., 18:0) and total saturated FA (38.3 vs. 45.1 wt%), and a higher concentration of in idual (e.g., 16:1) and total monounsaturated FA (58.2 vs. 52.7 wt%) in the Jersey animals. Other indices of desaturation calculated from the FA composition showed this same difference. The slip point of adipose tissue of Jersey cattle (36.8 degrees C) was significantly lower than that of Limousin cattle (39.2 degrees C), but Jersey adipose tissue had a greater content of beta-carotene. The positive relationship between adipose tissue beta-carotene and desaturation opposes the negative relationship between dietary beta-carotene and desaturation determined elsewhere. These results, however, lead to the hypothesis that some cattle have a reduced capacity to metabolize beta-carotene to various forms of vitamin A, a compound that can reduce delta9 desaturase enzyme activity. In addition, the higher level of intramuscular fat in Jersey cattle (6.97 vs. 3.82%) is possibly related to a lack of inhibition of the adipocyte differentiation genes by vitamin A.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/AN15172
Abstract: Beef cattle reproductive rate in northern Australia is low and substantial effort is underway to make improvements. Collection of calf birth date to inform female reproductive rate data is often not practical. Therefore, there is a need to find alternative methods for collecting birth date data. The aim of the project was to trial an automated animal weighing technology (walk over weigh) to estimate calving date for cows in a northern breeding herd grazing in an extensive pasture system. Two-hundred and thirty-two Wagyu cows from a herd of 1195 with confirmed pregnancy tests were stocked in a paddock with a walk over weigh unit at the entry point of the water yard. Each calf born in the paddock was weighed, ear-tagged and a DNA s le collected. After processing, cleaning and smoothing the data, weight profiles of the 232 cows over a 119-day period were analysed. From the weight profiles and confirmed DNA parentage, 96 out of a possible 162 (59%) cows that calved had a correct calving date prediction. It is proposed that improvements in calving date prediction could be increased through engineering changes designed to slow cow movement over the walk over weigh unit. The trial demonstrated with the proposed changes that walk over weigh could be used to estimate calving date in extensive beef herds, with the expectation that this information could be used in genetic evaluation to improve reproductive rate in northern Australia.
Publisher: Elsevier BV
Date: 2007
Publisher: CSIRO Publishing
Date: 17-04-2009
DOI: 10.1071/AN20664
Abstract: Context Mice bred to be genetically different in feed efficiency were used in this experiment designed to help improve our knowledge of the biological basis of variation in feed efficiency between in idual animals. Aims This experiment used mice to explore the metabolic basis of genetic variation in feed efficiency in the growing animal. Methods Mice bred to differ in residual feed intake (RFI) recorded over a postweaning test were used. After 11 generations of ergent selection, mice in groups were tested for RFI from 6 to 8, 8 to 10, and 10 to 12 weeks of age, and measured for traits describing the ability to digest feed, body composition, protein turnover, basal and resting metabolic rate, and level of activity. Key results Compared with the low-RFI (high efficiency) line mice, high-RFI mice consumed 28% more feed per day over their RFI-test, were no heavier, were leaner (16% less total fat per unit of bodyweight), did not differ in the fractional synthesis rate of protein in skeletal muscle or in liver, and had similar basal metabolic rates at 33°C. On an energy basis, the selection lines did not differ in energy retained in body tissue gain, which represented only 1.8% of metabolisable energy intake. The remaining 98.2% was lost as heat. Of the processes measured contributing to the higher feed intake by the high-RFI mice, 47% of the extra feed consumed was lost in faeces and urine, activity was 84% higher and accounted for 24%, the cost of protein gain was 6% higher and accounted for 2%, and the energy cost of digesting and absorbing the extra feed consumed and basal heat production could have accounted for 11 and 15% each. Conclusions Selection for low RFI (high efficiency) in mice was accompanied by an increase in body fat, an improvement in the process of digestion, a lower rate of protein turnover and a much lower level of activity. Selection did not result in major change in basal metabolic rate. Implications This experiment with mice provided new information on the biological basis of genetic differences in feed efficiency. The experiment investigated the relative importance of major energy-consuming metabolic processes and was able to quantify the responses in protein turnover and level of activity, being responses in energy-consuming processes that have proven difficult to quantitatively demonstrate in large farm animals.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN16745
Abstract: This study was conducted to evaluate the relationships between metabolisable energy (ME) intake and outputs of methane (CH4), rumen-derived carbon dioxide (rCO2), lung-derived carbon dioxide (lCO2), and total carbon dioxide output (tCO2) measured using an open-circuit gas-quantification system (GQS). Three trials were conducted to produce a wide range of energy intake and gas emissions to allow relationships between gas outputs and ME intake to be quantified. Gas emissions and ME intake were measured in eight Angus steers (455 ± 24.6 kg initial bodyweight Trials 1 and 2), and in eight pregnant Angus heifers (503 ± 22.0 kg initial bodyweight 5 months pregnant Trial 3). Animals were fed twice daily to allow ad libitum intake in Trial 1, whereas in Trials 2 and 3, feed intake was restricted and energy density was varied to provide a wide range of ME intakes. Animals were allocated to in idual pens during a 20-, 19- and 15-day experimental periods, and total faecal output was measured for the last 8, 4 and 4 days in Trials 1, 2 and 3 respectively. Gas emissions were measured for 16, 8 and 8 days after the adaptation period (4, 11 and 7 days) and each animal was allowed to visit the GQS every 2 h. Total CO2 in breath (tCO2) was separated into CO2 arising from rumen fermentation (rCO2) and CO2 in expired air from the lungs (lCO2) by manually identifying the eructations from normal breaths using the GQS gas-output trace. All CO2 outputs (lCO2, rCO2 and tCO2) were highly correlated with each other (r = 0.74–0.99 P 0.01). Measurement of CO2 output was more repeatable with fewer days of measurement than was CH4 output. Metabolisable-energy intake was closely related to all three measures of CO2 output (rCO2, r = 0.69, P 0.001 lCO2, r = 0.70, P 0.001 and tCO2, r = 0.73, P 0.001). Heat production was estimated from lCO2 output by assuming a value of 0.85 for the respiratory quotient of metabolised products. The heat production estimated at the extrapolated zero ME intake (0.52 MJ/kg0.75) was 60% higher than previous estimates of fasting heat production in cattle. However, our estimate was made under non-fasting, non-sedentary, non-thermoneutral conditions, so it may be a realistic estimate of maintenance energy requirement excluding heat increment of feeding. In conclusion, the open-circuit GQS can be used to provide estimates of the ME intake and heat production of cattle, and, as such, provides a valuable opportunity to describe the energy relations and efficiency of beef cattle in the field, with minimal interference to normal grazing patterns and behaviour.
Publisher: MDPI AG
Date: 15-02-2022
DOI: 10.3390/AGRICULTURE12020276
Abstract: Imputation can be used to obtain a large number of high-density genotypes at the cost of procuring low-density panels. Accurate imputation requires a well-formed reference population of high-density genotypes to enable statistical inference. Five methods were compared using commercial Wagyu genotype data to identify in iduals to produce a “well-formed” reference population. Two methods utilised a relationship matrix (MCG and MCA), two of which utilised a haplotype block library (AHAP2 and IWS), and the last selected high influential sires with greater than 10 progeny (PROG). The efficacy of the methods was assessed based on the total proportion of genetic variance accounted for and the number of haplotypes captured, as well as practical considerations in implementing these methods. Concordance was high between the MCG and MCA and between AHAP2 and IWS but was low between these groupings. PROG-selected animals were most similar to MCA. MCG accounted for the greatest proportion of genetic variance in the population (35%, while the other methods accounted for approximately 30%) and the greatest number of unique haplotypes when a frequency threshold was applied. MCG was also relatively simple to implement, although modifications need to be made to account for DNA availability when running over a whole population. Of the methods compared, MCG is the recommended starting point for an ongoing sequencing project.
Publisher: Wiley
Date: 06-05-2010
DOI: 10.1111/J.1365-2052.2009.01990.X
Abstract: beta, beta-carotene-9', 10'-dioxygenase (BCO2) plays a role in cleaving beta-carotene eccentrically, and may be involved in the control of adipose and milk colour in cattle. The bovine BCO2 gene was sequenced as a potential candidate gene for a beef fat colour QTL on chromosome (BTA) 15. A single nucleotide base change located in exon 3 causes the substitution of a stop codon (encoded by the A allele) for tryptophan(80) (encoded by the G allele) (c. 240G>A, p.Trp80stop, referred to herein as SNP W80X). Association analysis showed significant differences in subcutaneous fat colour and beta-carotene concentration amongst cattle with different BCO2 genotypes. Animals with the BCO2 AA genotype had more yellow beef fat and a higher beta-carotene concentration in adipose tissues than those with the GA or GG genotype. QTL mapping analysis with the BCO2 SNP W80X fitted as a fixed effect confirmed that this SNP is likely to represent the quantitative trait nucleotide (QTN) for the fat colour-related traits on BTA 15. Moreover, animals with the AA genotype had yellower milk colour and a higher concentration of beta-carotene in the milk.
Publisher: Oxford University Press (OUP)
Date: 2014
Abstract: Tenderness is the one of the most important attributes of beef with regards to the intent of consumers to repurchase. Beef tenderness is frequently measured objectively as Warner-Bratzler shear force. However, to better understand the genetics underlying tenderness, better descriptors were derived herein. Two traits, adjusted shear force and aging rate, were calculated to incorporate measures of Warner-Bratzler shear force repeated over aging time of 2 muscles, longissimus dorsi (LD) and semitendinosus (ST). Analysis of these traits indicated that the shear forces of the 2 muscles are lowly correlated and aging rate, as calculated, was not correlated with adjusted shear force. Breed, SNP, and QTL effects were analyzed for the 4 traits (2 traits × 2 muscles). For adjusted shear force, the QTL were located on cattle chromosomes BTA 5, 18, 25, and 29. With the exception of the QTL on BTA 5, the adjusted shear force QTL were observed for either the LD or the ST but not both muscles. The QTL for aging rate were located on BTA 1, 4, 7, 11, 13, 19, and 20.
Publisher: MDPI AG
Date: 22-12-2022
DOI: 10.3390/AGRICULTURE13010037
Abstract: Female fertility is essential to any beef breeding program. However, little genetic gain has been made due to long generation intervals and low levels of phenotyping. Days to calving (DC) is a fertility trait that may provide genetic gain and lead to an increased weaning rate. Genetic parameters and correlations were estimated and compared for DC across multiple joinings (first, second and third+) and lactation status (lactating and non-lactating) for a tropical composite cattle population where cattle were first mated as yearlings. The genetic correlation between first joining DC and mature joining DC (third+) was moderate–high (0.55–0.83). DC was uncorrelated between multiparous lactating and non-lactating cows (rG = −0.10). Mature joining DC was more strongly correlated with second joining lactating DC (0.41–0.69) than with second joining non-lactating DC (−0.14 to −0.16). Thus, first joining DC, second joining DC and mature joining DC should be treated as different traits to maximise genetic gain. Further, for multi-parous cows, lactating and non-lactating DC should be treated as different traits. Three traits were developed to report back to the breeding programs to maximise genetic gain: the first joining days to calving, the second joining days to calving lactating and mature days to calving lactating.
Publisher: Wiley
Date: 06-07-2007
DOI: 10.1111/J.1365-2052.2007.01623.X
Abstract: In this study, a highly significant quantitative trait locus (QTL) for meat percentage, eye muscle area (EMA) and silverside percentage was found on cattle chromosome 2 at 0-15 cM, a region containing the positional candidate gene growth differentiation factor 8 (GDF8), which has the common alias myostatin (MSTN). Loss-of-function mutations in the MSTN gene are known to cause an extreme 'double muscling' phenotype in cattle. In this study, highly significant associations of MSTN with cattle carcass traits were found using maternally inherited MSTN haplotypes from outbred Limousin and Jersey cattle in a linkage disequilibrium analysis. A previously reported transversion in MSTN (AF320998.1:g.433C>A), resulting in the amino acid substitution of phenylalanine by leucine at position 94 of the protein sequence (F94L), was the only polymorphism consistently related to increased muscling. Overall, the size of the g.433C>A additive effect on carcass traits was moderately large, with the g.433A allele found to be associated with a 5.5% increase in silverside percentage and EMA and a 2.3% increase in total meat percentage relative to the g.433C allele. The phenotypic effects of the g.433A allele were partially recessive. This study provides strong evidence that a MSTN genotype can produce an intermediate, non-double muscling phenotype, which should be of significant value for beef cattle producers.
Publisher: CSIRO Publishing
Date: 1992
DOI: 10.1071/AR9921417
Abstract: Australia's prime lamb industry is based on systematic three way crossbreeding. This paper examines various genetic effects on wool production, important determinants of profitability of the meat-sheep enterprise. Data from three purebred (Merino, Corriedale and Dorset Horn), six F1 and the six three-way cross lines were analysed. Direct genetic effects were important for all traits analysed. Maternal effects were generally not important. In idual heterosis was large for clean fleece weight (13%) and hogget weight (10%) and important also for fibre diameter (2%). Maternal heterosis averaged 3% for clean fleece weight, -2% for fibre diameter, and 1% for hogget weight (5% rams -3% ewes). These results support the hypothesis that the action of in idual heterosis through increased nutrient demand results in increased mature weights. Also, the effect of maternal heterosis is to increase nutrient supply resulting in increased rates of maturation.
Publisher: Springer Science and Business Media LLC
Date: 16-12-2017
Publisher: Oxford University Press (OUP)
Date: 05-2008
Abstract: This study investigated the effects of a SNP in the myostatin gene (MSTN or growth differentiation factor 8, GDF8) on birth, growth, carcass, and beef quality traits in Australia (Aust.) and New Zealand (NZ). The SNP is a cytosine to adenine transversion in exon 1, causing an amino acid substitution of leucine for phenylalanine(94) (F94L). The experiment used crosses between the Jersey and Limousin breeds, with the design being a backcross using first-cross bulls of Jersey x Limousin or Limousin x Jersey breeding, mated to Jersey and Limousin cows. Progeny were genotyped for the myostatin SNP and phenotyped in Aust., with finishing on feedlot (366 calves, over 3 birth years) and in NZ with finishing on pasture (416 calves, over 2 birth years). The effect of the F94L allele (A allele) on birth and growth traits was not significant. The F94L allele in Limousin backcross calves was associated with an increase in meat weight (7.3 and 5.9% of the trait mean in Aust. and NZ, respectively, P < 0.001), and a reduction in fat depth (-13.9 and -18.7% of the trait means on live calves (600 d) and carcasses, respectively, Aust. only, P < 0.001), intramuscular fat content (-8.2% of the trait mean in Aust., P < 0.05 -7.1% in NZ, not significant), total carcass fat weight (-16.5 and -8.1% of the trait mean, Aust. and NZ P < 0.001 and P < 0.05, respectively). Meat tenderness, pH, and cooking loss of the M. longissimus dorsi were not affected by the F94L variant. In the Jersey backcross calves, additive and dominance effects were confounded because the F94L allele was not segregating in the Jersey dams. The combined effects, however, were significant on LM area (4.4% in both Aust., P < 0.05, and NZ, P < 0.01), channel fat (-11.7%, NZ only, P < 0.01), rib fat depth (-11.2%, NZ only, P < 0.05), and carcass fat weight (-7.1%, NZ only, P < 0.05). The results provide strong evidence that this myostatin F94L variant provides an intermediate and more useful phenotype than the more severe double-muscling phenotype caused by knockout mutations in the myostatin gene.
Publisher: CSIRO Publishing
Date: 05-08-2021
DOI: 10.1071/AN21085
Abstract: Reciprocal recurrent selection is the selection of purebreds for crossbred performance and takes advantage of additive and non-additive variance by using pedigreed progeny performance records. Developed in maize, the adoption of this approach in livestock breeding has been limited to the pork and poultry industries genomic selection may facilitate its extension into the beef industry by replacing pedigree. The literature regarding the relative importance of additive versus non-additive variance and reciprocal recurrent genomic selection models was reviewed. The potential for using reciprocal recurrent genomic selection in a terminal Wagyu × Angus cross scenario was examined. Non-additive variance is more important for fitness traits and accounts for a small proportion of variance related to production traits such as marbling. In general, reciprocal recurrent selection was not significantly better at improving performance of crossbreds than was traditional selection within parental breeds using only additive variance in the studies examined. Simulation studies showed benefits of including dominance or breed-specific allele effects in prediction models but advantages were small as more realistic simulations were examined. On the basis of the evidence, it is likely that in a terminal two-way cross-beef scenario utilising Wagyu sires and Angus dams, where selection emphasis is on marbling, selection of purebreds on the basis of additive variance will allow substantial progress to be realised.
Publisher: MDPI AG
Date: 28-12-2021
DOI: 10.3390/ANI12010061
Abstract: Multiple studies have quantified the production differences of Hereford Angus crossbreds compared to purebred Angus for a range of traits including growth, carcass, and reproductive traits. This study aims to quantify breed and heterosis effects on maternal performance using genomics. Thirty Hereford and thirty Angus sires were mated to 1100 Angus heifers and cows in a large commercial herd run on pasture at Musselroe Bay, Tasmania, Australia. Approximately 1650 calves were born. Heifers were weaned, scanned for attainment of puberty prior to joining at approximately 15 months of age, joined, and then recorded for status of pregnancy, calving, lactating, 2nd pregnancy, and weaning of second calf. Heterozygosity effects were significant for heifer pre-joining weight and height as well as proportion pubertal. Breed differences were significant for the same traits plus pregnancy rate at second joining and proportion rearing two calves. Genetic parameters were reported for 13 traits. On average, higher genetic merit (Estimated Breeding Value, EBV percentile) Hereford bulls were used than Angus for growth and puberty, but they were similar for fat and reproduction. Days to calving BREEDPLAN EBVs of the sires were related to puberty and reproduction. Scrotal size BREEDPLAN EBVs of the sires were related to attainment of puberty genomic EBVs calculated. In summary, breed differences in growth and puberty were due to heterosis, but there was an advantage of Hereford genes for reproductive performance. Ongoing emphasis on selection for reduced days to calving and estimation of multi-breed EBVs is important.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN15090
Abstract: The profitability of a sheep enterprise is greatly influenced by the ability of the ewe to produce a lamb annually. This paper examines the between- and within-breed association between the liveweight and fat score of the adult ewe and key fleece, reproduction and milk production traits. The study analysed the performance of 2846 first-cross Merino and Corriedale ewes from the maternal central progeny test (MCPT) over their first three production cycles. Breed (9 sire breeds) and within-breed (91 sires) correlations were calculated from bivariate correlations of adult liveweight and fat score with fleece, reproduction and milk production traits. The mean liveweight and fatness of the breeds were low to moderately negatively correlated with greasy fleece weight (–0.55 and –0.25, respectively) and moderate to strongly positively correlated with fibre diameter (0.88 and 0.41, respectively). However, the within-breed correlations were generally low to negligible. The genetic relationships between ewe fat score and reproductive traits at the breed and within-breed level was generally low to negligible and, in some cases, negative under production conditions where the ewes were well managed and averaged a fat score of 3.5 pre-joining and became too fat across the production cycle. Strong breed correlations between ewe fat score and milk fat concentration (0.88) suggest that selection of fatter sire breeds will lead to increased fat in their progenies’ milk, which was associated with larger lambs. The potential advantages of selecting for more fat to improve the maternal performance of the ewe seem to be limited in enterprises where the production system can easily be adjusted to restrict the influence of temporary and long-term feed deficiencies, as was achieved within the MCPT research flocks.
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/AN20151
Abstract: Context The most common way of pricing beef carcasses is through a price grid. Most processors make greater profit from higher-quality carcasses, which are those with higher meat yield and eating quality. Aims The aim of this study was to calculate the value of erse carcasses and compare pricing mechanisms on their ability to discriminate variation in meat yield and predicted eating quality. Methods Hereford cross steer carcasses (153) were boned out to record saleable meat and yield. Six methods were used to calculate carcass price (AU$/kg). All were adjusted to the same average carcass value to allow comparisons, assuming that the overall payment does not change, but comparing the effect of having greater premiums and discounts. The six prices were based on a commercial grid, grid plus eating quality premium, yield of saleable meat only (constant price for all saleable meat), yield with eating quality premium, then the yield prices with optimum (quadratic) weight and fatness penalties based on grid optimums. Key results Measurements of meat quality (eye muscle area and marble score) or saleable meat yield accounted for no variation in the grid price. However, measurement of yield accounted for substantial variation in prices calculated from yield and eating quality. Conclusions The current grids do not encourage high-quality meat production and, assuming that yield and eating quality are important to processors, an actual measurement of yield is crucial to guide processing decisions (e.g. cutting plans) to maximise carcass value and feed market signals back to beef producers. Implications Improved measurement of meat yield is required if carcass prices are to reflect carcass quality or the potential value captured.
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/AN20153
Abstract: Context BREEDPLAN reports estimated breeding values (EBVs) for many traits, but there are few EBVs specifically for the inputs into the Meat Standards Australia (MSA) index for producers, so as to make genetic progress. It is not known how selection on current BREEDPLAN EBVs influences the MSA index and whether these relationships are the same for different market end-points. Aims The aim of the present study was to examine the extent to which the MSA index of commercial animals is related to sire EBVs. Methods Data from 12 industry or research datasets (6997 animals) from four breeds (Angus, Charolais, Hereford and Limousin), three feeding regimes (pasture-, short- and long-fed) and 433 sires have been included for analysis. Carcass traits (intramuscular fat (IMF), MSA marbling, eye-muscle area, MSA index, rib, ossification and hot standard carcass weight) were regressed on BREEDPLAN sire EBVs (IMF EBV, eye-muscle area EBV, 600-day weight EBV, rib EBV). Sire ariance components were estimated for each of the 12 datasets, to determine whether the genetic variance in the MSA index and its indicator traits changed with carcass weight. Key results Sire variation in carcass traits changed with market end-point (or feeding regime) for all carcass traits except ossification, where there was no difference between long- and pasture-finished systems. One of the biggest differences between market end-points was observed in marbling where there was a 5.5-fold increase in the sire standard deviation for a long-feedlot finish system relative to pasture (1619 long vs 352 pasture finish). The sire EBV that had the greatest effect on the MSA index was IMF. A 1-unit increase in IMF EBV was associated with an improvement in the MSA index by only 0.34 units for long-fed cattle or 0.12 units for cattle finished on pasture. Furthermore, the regression coefficient between carcass traits and the sire EBV for the same trait was significantly lower for pasture-finished than for long-fed cattle. Conclusions and implications This means that commercial producers are unlikely to be receiving the full benefits of purchasing superior eating-quality sires unless they receive a premium from the finishing or wholesale meat sectors where the benefits are captured or they retain ownership through to heavier finish weights.
Publisher: CSIRO Publishing
Date: 06-04-2023
DOI: 10.1071/AN22453
Abstract: Context Reproduction is an economically important trait in both males and females however, the relationships between fertility and body composition traits are little researched, but essential to breeding programs, as they will help inform selection decisions and allow the greatest opportunity for genetic gain. Aims Estimate genetic and phenotypic correlations between male and female yearling fertility traits and investigate their relationship with yearling body composition traits, which have an effect on the attainment of puberty. Methods Genotype and phenotype data were obtained from a tropical composite commercial cattle population and imputed to 27 638 single nucleotide polymorphisms. A series of univariate and bivariate linear mixed models using a genomic relationship matrix were run to estimate genetic parameters, genetic and phenotypic correlations for a series of male and female fertility and body composition traits. These parameters were then compared to help understand the genetic relationships. Key results Scrotal circumference was favourably genetically correlated with weight (0.34), fat traits (0.06–0.24), muscle (0.24) and heifer days to calving (−0.32). Heifer days to calving was favourably correlated with muscle (−0.18) but not fat traits (0.11 to 0.21). The genetic correlations between heifer days to calving and sperm morphology traits were generally unfavourable (−0.32 to 0.25). Sperm morphology traits were favourably genetically correlated with fat traits (−0.84 to 0.31) and muscle (−0.61 to 0.31) but not weight (−0.15 to 0.09). Conclusions and implications Yearling sperm morphology traits were unfavourably correlated with heifer days to calving, indicating that they are not good candidates for indirect selection on improving female fertility in the herd. A different trend was found for yearling scrotal circumference and heifer days to calving, identifying it as a good candidate for indirect selection of heifer fertility as it is easy to measure and heritable. The genetic correlations estimated between composition traits with male and female fertility traits allow breeding programs to make an informed selection decision to optimise genetic gain across all traits.
Publisher: Wiley
Date: 14-04-2011
DOI: 10.1111/J.1365-2052.2011.02197.X
Abstract: A whole-genome scan was carried out in New Zealand and Australia to detect quantitative trait loci (QTL) for live animal and carcass composition traits and meat quality attributes in cattle. Backcross calves (385 heifers and 398 steers) were generated, with Jersey and Limousin backgrounds. The New Zealand cattle were reared and finished on pasture, whilst Australian cattle were reared on grass and finished on grain for at least 180 days. This paper reports on meat quality traits (tenderness measured as shear force at 4-5 ages on two muscles as well as associated traits of meat colour, pH and cooking loss) and a number of metabolic traits. For meat quality traits, 18 significant QTL (P < 0.05), located in nine linkage groups, were detected on a genome-wise basis, in combined-sire (seven QTL) or within-sire analyses (11 QTL). For metabolic traits, 11 significant QTL (P < 0.05), located in eight linkage groups, were detected on a genome-wise basis, in combined-sire (five QTL) or within-sire analyses (six QTL). BTA2 and BTA3 had QTL for both metabolic traits and meat quality traits. Six significant QTL for meat quality and metabolic traits were found at the proximal end of chromosome 2. BTA2 and BTA29 were the most common chromosomes harbouring QTL for meat quality traits QTL for improved tenderness were associated with Limousin-derived and Jersey-derived alleles on these two chromosomes, respectively.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN14577
Abstract: The present paper quantifies the variation in selection direction and genetic merit for the 10 Angus seedstock herds that contributed the majority of the data to the industry herd component of the Beef CRC Maternal Productivity Project. Differences in multi-trait selection direction for 17 BREEDPLAN estimated breeding values (EBVs) ranged between 16 and 63 degrees. Important differences among herds for selection direction for in idual EBVs were identified. Specifically, some herds had been selecting to increase rib-fat and rump-fat EBV, while others were decreasing them. On the basis of a principal component analysis, 78% of the between herd difference in genetic merit as assessed by 17 EBVs was accounted for by two principal components. For 2000-born calves, the first principal component accounted for 50% of the genetic variation between herds and was most closely associated with days to calving EBV. Of the genetic merit for 2009-born calves, the first principal component accounted for 49% of the between herd variation and had the strongest weightings with BREEDPLAN rib-fat and rump-fat EBVs. The second principal component accounted for 29% of the variation and was most strongly related with BREEDPLAN EBVs for traits gestation length, milk and eye muscle area and 200-, 400- and 600-day weight. The variation at 2009 is consistent with outcomes from qualitative research that hypothesised that the main differences in genetic merit among herds are associated with rib-fat and rump-fat EBVs, but there were also differences in selection emphasis for weight traits. Despite differences in genetic merit among herds being generally small, they will manifest themselves in different productivity outcomes depending on the management system. Seedstock breeders and bull buyers should be aware of this and target their animal selection accordingly.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/AN13247
Abstract: The Australian sheep industry has historically made rapid advances in the quality and quantity of meat and wool through genetic improvement, but unfortunately, maternal performance, i.e. number of lambs weaned, is well below desired levels. The aim of the present paper is to investigate the potential to select for increased weight and fat across the production cycle to improve maternal performance. The analysis explores the potential to improve the weight and fat score of breeding ewes during ‘tough’ periods (i.e. when nutrient requirements are not met by the pasture), preparing the breeding ewe for the upcoming mating without an increase in overall ewe size. The 2846 ewes within the maternal central progeny test were weighed and scored for fatness 12 times across three production cycles. Low to moderate heritability estimates for weight (0.04–0.23) and fat (0.02–0.06) changes across the production cycle provide little hope for selection against weight loss during tough periods. The analysis showed very strong genetic correlations between time-points across multiple production cycles for both weight (0.99–0.93) and fat score (0.88–0.98). The very strong correlations between measurements suggest that weight and fat score are genetically the same trait throughout the ewe’s adult life. With 74% and 77% of the genetic variation in weight and fat, respectively, constant across the production cycle, there is little opportunity to select against the natural fluctuations in weight and fat reserves. In conclusion, selection for increased fat can be made at any time and it will result in more fat during tough times.
Publisher: Wiley
Date: 04-2006
DOI: 10.1007/S11745-006-5107-5
Abstract: A group of Angus beef cattle was removed from temperate pastures and fed a very low beta-carotene cereal-based ration in a feedlot for over 300 d. Half the group was supplemented weekly with retinyl palmitate (at the rate of 60,000 IU vitamin A/100 live weight (LW)/day), sufficient to offset clinical vitamin A deficiency the other half received no supplement. Blood was s led from all animals at biweekly intervals to assess beta-carotene and vitamin A status. Adipose tissue was s led by biopsy on three occasions throughout the experimental period and at slaughter to assess FA composition. Muscle was s led at slaughter to determine the intramuscular fat content. The mean plasma concentration of beta-carotene of all animals fell from an initial value of 20.1 to 5.2 microg/mL at 14 d, to 1.4 microg/mL at 35 d, and to zero at 105 d. Mean vitamin A in plasma was not significantly different between the treatment groups initially. The values then rose to almost twice their initial values by 35 d, but subsequently fell to below initial values by day 119. Thereafter, plasma vitamin A of the supplemented group was significantly greater than that of the unsupplemented group (P < 0.05). Muscle s les at slaughter from supplemented animals contained significantly (P < 0.01) more intramuscular lipid (13.0 vs. 9.6%). Major changes occurred over time in FA composition in both groups. Saturated FA decreased as monounsaturated FA increased over the first 60 d. An index of desaturation of FA was significantly lower (P < 0.001) in the vitamin A-supplemented group than in the nonsupplemented group. M.P. of the adipose tissue of nonsupplemented animals was 32.3 degrees C, significantly less (P< 0.05) than that of supplemented animals (34.1 degrees C). Feeding vitamin A was associated with less intramuscular fat but with a less desirable (less unsaturated, more solid) FA profile.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN15465
Abstract: Considerable information exists on genetic relationships of body composition and carcass quality of young and finished beef cattle. However, there is a dearth of information on genetic relationships of cow body composition over time and, also, relationships with young-animal body-composition measures. The aim of the present study is to understand genetic relationships among various cow body-composition traits of Angus cows over time, from yearling to weaning of a second calf at ~3.5 years. To determine genetic correlations among various composition traits over time, a multi-trait–multi-time analysis is required. For the Maternal Productivity Project, this necessitates modelling of five traits (namely weight and ultrasound measure for loin eye muscle area (EMA), rib fat, P8 rump fat and intramuscular fat) by five time combinations (recordings at yearling then pre-calving and weaning in first and second parity). The approach was based on including all 25 trait-by-time combinations in an analysis using factor analytic models to approximate the genetic covariance matrix. Various models for the residual covariance structure were investigated. The analyses yielded correlations that could be compared with those of past studies reported in the literature and, also, to a set of bivariate analyses. Clustering of the genetic multi-trait–multi-time correlation structure resulted in a separation of traits (weight and EMA, and the fat traits) and also of time effects into early (heifer = before first lactation) and late (cow = post-first lactation) measurements.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13321
Abstract: Residual feed intake (RFI) is the difference between an animal’s actual feed intake and that which would be expected based on production. This experiment was to test the hypothesis that part of the variation in RFI may be due to differences in energetic efficiency through changes in heat production, these being in part due to differences in protein metabolism. Following three generations of ergent selection for RFI, eight High and eight Low-RFI heifers were fed at both 105% and 180% of predicted maintenance feed requirements. Between-RFI line and feeding-level differences were assessed for energy intake, protein metabolism, heat production, body composition, energy and nitrogen balance and digestibility. The RFI lines did not differ in protein metabolism or heat production. The High-RFI heifers deposited 51% and 56% more subcutaneous fat at the P8 rump and 12/13th rib sites, respectively, with no difference in eye muscle area gain or average daily weight gain. The greater fat deposition of High-RFI heifers was due to a larger ad libitum feed consumption compared with the Low-RFI heifers. Energy and nitrogen balance did not differ between the RFI lines. The energy transactions indicated no difference in the efficiency of energy use on 105% maintenance, although when fed 180% of maintenance the differences in feed intake suggest variation in appetite as the mechanism contributing to RFI. All of the extra energy consumed by High-RFI heifers above maintenance and deposition of protein was associated with additional energy retained as fat. This study suggests that selection for RFI may not lead to improved efficiency of energy use.
Publisher: Science Alert
Date: 03-2009
DOI: 10.3923/PJBS.2009.545.547
Abstract: A Principal Component Analysis (PCA) was conducted on the matrix of correlations among P8 fat measures at seven different ages for steers and heifers. The P8 fat measures were collected from 1143 steers and heifer calves that were born to Hereford (h) dams inseminated with semen from seven different sire breeds: Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu, over a 4-year period (1994 to 1997). The first two principal components explained 61 and 57% of the total phenotypic variation in fatness for steers and heifers, respectively. The first component was positively correlated to all measures and was interpreted as a measure of overall fatness. The second component was positively correlated to fatness approximately pre-weaning and negatively correlated thereafter and thus was interpreted as maturity type but could be a function of milk supply. When estimated from a sire model, the heritability estimates were high for the first component (0.59 and 0.67 for steers and heifers, respectively) but low for the second component (0.05 and 0.19). The results demonstrate the value of combining information across multiple measurements to build accuracy, even when relatively crude methods are used.
Publisher: Wiley
Date: 12-2002
DOI: 10.1046/J.1365-2052.2002.00909.X
Abstract: This study describes development of a consensus genetic linkage map of bovine chromosome 24 (BTA24). Eight participating laboratories contributed data for 58 unique markers including a total of 25 409 meioses. Eighteen markers, which were typed in more than one reference population, were used as potential anchors to generate a consensus framework map. The framework map contained 16 loci ordered with odds greater than 1000:1 and spanned 79.3 cM. Remaining markers were included in a comprehensive map relative to these anchors. The resulting BTA24 comprehensive map was 98.3 cM in length. Average marker intervals were 6.1 and 2.5 cM for framework and comprehensive maps, respectively. Marker order was generally consistent with previously reported BTA24 linkage maps. Only one discrepancy was found when comparing the comprehensive map with the published USDA-MARC linkage map. Integration of genetic information from different maps provides a high-resolution BTA24 linkage map.
Publisher: Informa UK Limited
Date: 03-07-2014
Publisher: Wiley
Date: 10-11-2010
DOI: 10.1111/J.1365-2052.2010.02058.X
Abstract: A QTL study of live animal and carcass traits in beef cattle was carried out in New Zealand and Australia. Back-cross calves (385 heifers and 398 steers) were generated, with Jersey and Limousin backgrounds. This paper reports on weights of eight organs (heart, liver, lungs, kidneys, spleen, gastro-intestinal tract, fat, and rumen contents) and 12 fat composition traits (fatty acid (FA) percentages, saturated and monounsaturated FA subtotals, and fat melting point). The New Zealand cattle were reared and finished on pasture, whilst Australian cattle were reared on grass and finished on grain for at least 180 days. For organ weights and fat composition traits, 10 and 12 significant QTL locations (P<0.05), respectively, were detected on a genome-wide basis, in combined-sire or within-sire analyses. Seven QTL significant for organ weights were found at the proximal end of chromosome 2. This chromosome carries a variant myostatin allele (F94L), segregating from the Limousin ancestry, and this is a positional candidate for the QTL. Ten significant QTL for fat composition were found on chromosomes 19 and 26. Fatty acid synthase and stearoyl-CoA desaturase (SCD1), respectively, are positional candidate genes for these QTL. Two FA QTL found to be common to sire groups in both populations were for percentages of C14:0 and C14:1 (relative to all FAs) on chromosome 26, near the SCD1 candidate gene.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN12428
Abstract: Cow–calf efficiency or maternal productivity is highly correlated with total system efficiency of beef production. Balancing the needs of the cow herd with other production components is a daily challenge beef producers address to maximise the number of calves born and raised to weaning and, in turn, maximise maternal productivity. Pressure to satisfy modern consumer needs has shifted selection emphasis to production traits at the expense of fitness traits allowing adaptability to decline. Balancing the needs of the cow herd with production objectives presents cow–calf producers with the challenge of genetically tailoring their cattle to modern needs, while sustainably managing these cattle and natural resources. This balancing act is highlighted by the debate surrounding the application of residual feed intake to reduce costs associated with provision of feed for beef production. Some uncertainty surrounds the relationships between efficiency, production and maternal productivity traits. This review examines key components and definitions of maternal productivity. Management decisions as well as cow and calf traits have important interacting impacts on maternal productivity. Achieving a calving interval of 365 days represents the single most important production issue affecting maternal productivity and is dependent on heifer development during early life and energy reserves (i.e. body condition score) in subsequent years. Management issues such as calving date and selection decisions interact with environmental factors such as photoperiod and production traits such as feed intake, and previous production levels, to influence heifer development and cow body energy reserves. Some proposed definitions of maternal productivity simply include weaning weight per cow mated which can be averaged over all progeny weaned during a cow’s lifetime. Ideally, a definition should include the inputs and outputs of maternal productivity. Some definitions express maternal productivity over large time scales, e.g. a cow’s productive lifetime. Most definitions focus on the cow–calf unit, while some include progeny growth and feed intake to slaughter. This review recommends a definition that focuses on the cow–calf unit, as follows: (weight of calf weaned and cow weight change)/(metabolisable energy intake per cow and calf unit). This definition has the capacity to be scaled up, to include progeny postweaning production, as well as being applicable over varying time scales (e.g. 1 year to a cow’s whole productive life). Improvements in all facets of maternal productivity using this definition can be expected to improve beef-production efficiency.
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.MEATSCI.2008.07.007
Abstract: Texture parameters (peak force and compression), muscle myofibre diameter, and hydroxyproline were measured in semitendinosus s les from a cattle gene-mapping herd. The data were analysed to determine the relationships between these traits. The traits were also mapped by genetic linkage analysis to identify quantitative trait loci, and hence, candidate genes for these traits. Neither texture parameters were affected by the muscle structural traits of myofibre diameter or collagen content (as measured by hydroxyproline), despite significant variation in these traits between animals. QTL for the texture parameters of peak force and compression, as well as collagen content, were found on cattle chromosome 2 (BTA2) and attributed to the myostatin gene. Within the cattle population used for the QTL mapping, a gene variant of myostatin, F94L, has been previously shown to increase muscle mass, predominantly in the semitendinosus. It was determined herein that the F94L myostatin homozygous animals had more tender meat as measured by both peak force and compression. The variant was also responsible for a reduction in the collagen/elastin content of muscle. The myostatin F94L variant had no effect on muscle myofibre diameter of the semitendinosus, even though the variant causes substantial increases in muscle mass. Consequently, the increase in muscle mass of the variant must be due to myofibre hyperplasia and not hypertrophy. In addition, myostatin effects on tenderness are caused by changes in the extracellular matrix rather than muscle myofibre diameter.
Publisher: CSIRO Publishing
Date: 14-10-2021
DOI: 10.1071/AN21077
Abstract: Context The present work was motivated by beef breeder concerns that selection for high growth and low fat in steers and low mature weight in cows will lead to cows that have low body condition and, therefore, productivity. Aims The aim of this was to partition cow weight into size (associated with height) and condition (variation net of height) and test whether the trait net weight is a worthy addition to breeding programs. Methods Angus cows (5901) were measured as heifers (4889) and at pre-calving and weaning of their first and second calf (minimum 2690) for weight, height and body condition traits (condition score, ultrasound eye-muscle area, P8 and rib fat depth, and intramuscular fat percentage). A novel trait was developed by fitting height as a covariate to weight, with the residuals termed net weight. Key results Net weight was both heritable and genetically correlated with cow condition score and ultrasound measures. However, despite having a lower heritability, condition score was a more effective measure for genetic improvement of cow condition. Conclusions A measure of cow condition should be included in genetic evaluation programs but net weight is unlikely to be that measure. Implications Condition score should be recorded at the time of mature cow weight for breeding programs.
Publisher: Wiley
Date: 06-12-2013
DOI: 10.1111/AGE.12012
Abstract: A quantitative trait locus (QTL) study of the concentrations of 14 trace and macro elements (minerals) in tissues of beef cattle was conducted in New Zealand. Back-cross calves with Jersey and Limousin ancestry (202 heifers and 211 steers) were generated using first-cross sires. This paper reports on testing for effects of QTL on the concentrations of minerals in liver, kidney and muscle in cattle at slaughter, following a growth phase during which rearing and finishing stages were on pasture. Fifteen QTL were identified (P < 0.05) on a genome-wide basis in combined-sire and within-sire analyses. In addition, the possible effect of the Limousin myostatin F94L allele was tested by fitting each calf's myostatin genotype, and 16 QTL were identified. Twelve were in common with those QTL identified previously, comprising six affecting the liver (copper and zinc, on two chromosomes each plus iron and molybdenum), three affecting the kidney (calcium, copper and iron), and three affecting muscle (iron, strontium and zinc).
Publisher: Wiley
Date: 10-07-2006
DOI: 10.1111/J.1365-2052.2006.01483.X
Abstract: Single nucleotide polymorphisms (SNPs) in the calpain 1 (CAPN1) and calpastatin (CAST) genes were studied to determine their effects on meat tenderness in Bos taurus cattle. Strip loins (M. longissimus dorsi) were removed from cattle in four resource populations after slaughter (n = 1042), aged under controlled conditions until fixed times after rigor mortis, cooked and measured using a tenderometer. Animals were genotyped for the CAPN1 SNP c.947C>G (p.Ala316Gly AF252504) and for the CAST SNP c.2959A>G (AF159246). Frequencies of CAPN1 C alleles ranged from 23% to 68%, and CAST A alleles from 84% to 99.5%. From all data combined, the CAPN1 CC genotype (compared with the GG genotype) was associated with a 20.1 +/- 1.7% reduced average shear force at intermediate stages of ageing (P < 0.001) and with a 9.5 +/- 1.3% reduction near ultimate tenderness (P < 0.001). The heterozygote was intermediate. For CAST, corresponding values for AA compared with AG genotypes were reductions of 8.6 +/- 2.0% and 5.1 +/- 1.6% respectively (both P < 0.001), but there were too few GG genotypes for comparison. There were small interactions between the CAPN1 and CAST genotypes. For the CAPN1 and CAST genotypes combined, the maximal genotype effect in average shear force was 25.7 +/- 5.5% (P < 0.001) at intermediate stages and 15.2 +/- 4.8% near ultimate tenderness (P < 0.01).
Publisher: Springer Science and Business Media LLC
Date: 26-02-2007
Publisher: Springer Science and Business Media LLC
Date: 24-08-2007
DOI: 10.1007/S11250-007-9014-4
Abstract: Data consisting of 18 884 weight records collected from 1273 Boran cattle from birth to 24 months of age were used to estimate covariance functions and genetic parameters for growth of Boran cattle using random regression (RR) models under a situation of small herd size and inconsistent recording. The RR model fitted quadratic Legendre polynomials of age at recording for additive genetic and permanent environmental effects. Genetic variance increased from birth, reaching an asymptotic value at 455 days and was maximum at 525 days of age after which it gradually dropped. Permanent environmental variance increased throughout the trajectory. Estimates of temporary environmental variance were heterogeneous across ages. Direct heritability and permanent environmental variance as a proportion of phenotypic variance fluctuated greatly during the early ages but later stabilized at intermediate to later ages the estimates ranged from 0.11 to 0.33 and from 0.18 to 0.83, respectively. Genetic correlation estimates were positive, ranging from 0.10 to unity. The estimates declined with increasing in lag between the age points. Phenotypic correlation pattern was erratic between early ages, negatively low (-0.02) between the extreme data points and moderate to highly positive (>0.50) between intermediate and later points, with prominent spikes along the diagonal. It is concluded that RR models have potential for modelling growth of Boran cattle, notwithstanding conditions of small herd sizes and inconsistent recording.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13054
Abstract: Australian seedstock cattle breeders have expressed concerns that while there has been genetic improvement in feedlot and abattoir performance of cows, it could have led to a decline in maternal productivity, especially under variable nutritional conditions. This paper describes a substantial project with two components designed to address these issues. The first sub-project was to monitor bodyweight and composition of 7760 young Angus and Hereford cows as they experience variable physiological states (pregnancy and lactation) and seasons. This was conducted on large numbers in seedstock herds. The second sub-project was to monitor more regularly bodyweight, body composition, and calf rearing performance of 500 Angus cows that are genetically ergent for either fat or residual feed intake at two research centres. This also included two levels of nutrition and recording of weekly feed intake of small groups of cows for at least three parities to allow reporting of genotype × nutrition effects on maternal productivity and efficiency. Results from the project are reported in a series of papers with each one having a defined focus.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN17779
Abstract: Two small pen trials with cattle and sheep both clearly demonstrated that while there is significant variation in residual feed intake when on high energy supply, there is negligible variation when energy supply is limited. A review of literature demonstrated that this is also the case when energy supply is limited by heat or physiological state, such as peak lactation, and in multiple species. There is little evidence of variation in efficiency of maintenance requirements, growth or lactation. Nor is there strong evidence for large variation in digestibility within breeds, despite some differences between ergent breeds. Thus, the primary source of variation in residual feed intake must be in appetite and, in variable environments, it is possible that those with greater appetite are more resilient during times of feed shortage.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13295
Abstract: This experiment evaluated the productivity of 500 Angus cows that differed in genetic merit for either subcutaneous rib fat depth (Fat) or residual feed intake (RFI) based on estimated breeding values (EBVs) and managed under two levels of nutrition. Reproductive rate over four calving opportunities in mature cows and growth performance of progeny to weaning was assessed. Level of nutrition significantly affected all body composition traits for both Fat and RFI line cows. Cows on High-Nutrition were 14–16% heavier (P 0.001) than those on Low-Nutrition. Differences in EBVs for fatness were reflected in phenotypic fatness at maturity. High-RFI line cows were fatter for both scanned rump (P8) and rib (RIB) fat depth relative to their Low-RFI contemporaries. Of those cows that were lactating, there was no significant effect of line or nutrition on pregnancy rate or days to calving (DC). There was, however, a trend (P 0.1) in the Low-Fat line cows towards longer DC compared with the High-Fat line cows. There was no significant effect of either line or nutrition on calf birthweight. Calves with mothers on High-Nutrition were 8% heavier at weaning (P 0.001) than those on Low-Nutrition. Lower EBVs for RFI was associated with higher 200-day growth EBV and heavier calves at weaning. Current carcass BREEDPLAN EBVs can be used to select for changes in cow body composition if desired. In this experiment, Angus cows selected for lower RFI or with below-average fatness EBV and had raised a calf at every previous opportunity were not compromised in pregnancy rate or DC at maturity under varying nutrition such as can be experienced during normal seasonal conditions in southern Australia. However, selection for lower RFI was associated with lower weaning rate (P 0.05), which warrants further investigation to confidently predict the implications for commercial cattle production.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13533
Abstract: Relationships between BREEDPLAN estimated breeding values (EBVs) for 600-day weight, maternal effect on calf weaning weight (Milk), fat depth at P8 site (Rump), 12/13th rib fat depth (Rib), eye muscle area (EMA), and intramuscular fat (IMF) with body composition measures in first- and second-parity Angus and Hereford cows were investigated. More than 4000 Angus and 1000 Hereford cows were measured for weight, height, ultrasound P8 fat depth (P8), 12/13th rib fat depth (RIB), loin EMA and IMF (%) at pre-calving and weaning. The body composition measurements were then regressed against mid-parent BREEDPLAN EBVs. Increased 600-day weight EBV was associated with increased weight and height but decreased P8 and rib fat depths and EMA when considered on a weight-constant basis. BREEDPLAN EBVs for Rump, Rib, EMA and IMF were closely related to the equivalent ultrasound measure in Angus and Hereford cows at pre-calving and weaning in the first two parities. These results indicate that current BREEDPLAN carcass EBVs are associated with cow body composition, so if producers want to change the body composition of their cows, they can do so using existing BREEDPLAN carcass EBVs, and there appears no requirement for additional EBVs to describe cow body-composition traits for subcutaneous fat, EMA and IMF.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN13258
Abstract: The genetics of body composition traits measured before calving and at weaning in the first and second parities were evaluated in 5975 Angus and 1785 Hereford cows. Traits measured were liveweight, body condition score and hip height and ultrasound scanned measurements of subcutaneous P8 and 12/13th rib fat depth, loin eye muscle area and intramuscular fat percentage. Corresponding yearling measures on these animals were obtained for analyses of relationships between yearling information with later-in-life traits. There was moderate genetic variation in all body composition traits measured at pre-calving and weaning in Angus (h2 = 0.14–0.59) and Hereford (h2 = 0.14–0.64) cows. Genetic correlations between measurements of the same trait at pre-calving and weaning were consistently positive and high in both parities for both breeds, indicating animals were ranking similarly for the same trait measured over time. Genetic correlations between measurements of different traits were generally consistent over time (pre-calving and weaning) in both breeds, indicating genetic relationships between traits were not changing significantly over time. Genetic correlations with corresponding yearling measures of body composition were consistently positive and high for the first parity, and lower for the second parity. The results of this study indicate that genetic improvement in body composition traits in cows is possible, and that body composition information recorded at yearling age is a reasonably good predictor of later in life performance for these traits.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN14583
Abstract: The pregnancy rate of heifers affects the efficiency and profitability of beef herds. Heifers extreme in rib fatness (Fat) or post-weaning residual feed intake (RFI) estimated breeding values (EBVs) were evaluated for their pregnancy rates at two locations in the southern agricultural regions of Australia (Struan and Vasse) as part of the Beef Cooperative Research Centre Maternal Productivity Project. Heifers ergent in Fat (High-Fat and Low-Fat) had differences in fat depth pre-joining at the 12/13th rib (4.4 mm vs 3.5 mm) and P8 rump site (6.1 mm vs 4.8 mm). This was associated with significant differences in pregnancy rates over a 9-week joining period (91.5% vs 83.0%) and an even larger difference when calculated over a 6-week joining period (77.3% vs 65.0%). Heifers ergent in RFI (Vasse only) also differed in rib fat (7.6 mm vs 6.4 mm) and P8 fat (11.0 vs 9.2 mm), but not significantly in pregnancy rates between the two RFI (High-RFI and Low-RFI) genotypes following a 9-week (92.4% vs 88.5%) or 6-week (81.2% vs 73.7%) joining period. The phenotypic analysis of the Fat and RFI heifers together indicated that weight and fat depth were the largest contributing factors to variation in pregnancy rates, and age and pre-joining weight gain were not significant. These phenotypic characteristics indicated that producers can manage heifers to particular weight and fat combinations to improve heifer conception rates. Associations of BREEDPLAN EBVs with heifer fertility showed that a shorter days-to-calving EBV had the biggest impact (P 0.001) on heifer pregnancy rates and rib fat and scrotal size EBVs were close to significant (P 0.10).
Publisher: Springer Science and Business Media LLC
Date: 24-03-2012
DOI: 10.1007/S00335-012-9396-0
Abstract: Beef with yellow fat is considered undesirable by consumers in most European and Asian markets. β-Carotene is the major carotenoid deposited in the adipose tissue and milk fat of cattle (Bos taurus), which can result in the yellowness. The effects of retinal short-chain dehydrogenase reductase (RDHE2) and β, β-carotene 9',10-dioxygenase (BCO2) were considered jointly as major candidate genes for causing the yellow fat colour, based on their genomic locations in the fat colour quantitative trait loci (QTL) and their roles in the metabolism of β-carotene. In a secondary pathway, BCO2 cleaves β-carotene into retinoic acid, the most potent form of vitamin A. RDHE2 converts trans-retinol to trans-retinal, a less active form of vitamin A. We evaluated the effects of two amino acid variants of the RDHE2 gene (V6A and V33A) along with a mutation in the BCO2 gene that results in a stop codon (W80X) in seven cattle populations. The RDHE2 V6A genotype affected several fat colour traits but the size of the effect varied in the populations studied. The genotype effect of the RDHE2 V33A variant was observed only in New Zealand s les of unknown breed. In general, the in idual effects of RDHE2 V6A and V33A SNPs genotypes were greater in the random New Zealand s les than in s les from pedigreed Jersey-Limousin backcross progeny, accounting for 8-17 % of the variance in one population. Epistasis between the BCO2 W80X and RDHE2 variants was observed, and in some populations this explained more of the variation than the effects of the in idual RDHE2 variants.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/AN11033
Abstract: The use of animals that are resilient to challenging environments is becoming of increasing importance in animal production systems. Interest in breeds of sheep such as the Damara for sheep meat production is increasing in Australia. Anecdotally this breed outperforms the traditionally grazed Merino in the harsh rangeland environments encountered in the Pastoral Zone of Australia, but little evidence is available to support this claim. A trial was conducted to quantify differences in the efficiency of feed utilisation and growth performance of Damara and Merino sheep under two contrasting dietary regimes. Eighteen castrate males of each breed were offered a ‘low-quality’ diet (L) (7 MJ/kg ME 8% crude protein, as per manufacturer’s analysis) followed by a ‘high-quality’ diet (H) (11 MJ/kg dry matter and 16% crude protein, as per manufacturer’s analysis). On the L diet, Damaras had similar ad libitum feed intake as Merinos, but the digestibility of feed dry matter and energy was ~10% higher in Damaras than Merinos. Damaras also gained weight (38 g/day) on the L diet, while Merinos lost weight (28 g/day) (P 0.002). On the H diet the Damaras consumed 14% more feed (P 0.053) and grew 30% faster than Merinos (P 0.002), but there was no difference in the apparent dry matter or energy digestibility of the feed. At the conclusion of the trial the Damara carcasses were 22% heavier (28.1 versus 23.1 kg), and had higher dressing percentages (53.2 versus 41.5%) than Merinos, but the proportions of carcass components did not differ. The Damaras achieved higher total digestible energy intakes than the Merinos on both diets. On the low-quality feed this was achieved through higher feed digestibility and on the high-quality feed through greater voluntary feed intake. We speculate that this arises from variation between the breeds in rumen volume, particle flow and the site of digestion, but further studies are required to confirm this contention. The ability of Damara sheep to obtain more nutrients from widely differing feed bases makes them an attractive alternative sheep breed for sheep meat production. Furthermore, the presence of such variation between genotypes offers potential for selective breeding and development of commercial lines of sheep.
Publisher: Elsevier BV
Date: 11-2011
Publisher: Elsevier BV
Date: 12-2008
Publisher: Springer Science and Business Media LLC
Date: 06-2007
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/AN13249
Abstract: The profitability of southern Australian sheep production systems depends on the optimisation of stocking rates by meeting the nutritional demands of the breeding ewe while effectively utilising grown pasture. The aim of the study was to evaluate the genetic variation in liveweight and body condition of Merino ewes across their breeding life within a wool-based enterprise. The results were consistent with findings in crossbred ewes and showed that the genetic component of weight and body condition remained constant across the production cycle and age. The overall additive genetic effect accounted for 92% of the genetic variation in weight of Merino ewes bred across five production cycles. A genetic correlation of 0.85 suggested that ewes that were superior at maintaining their condition when rearing a single lamb would maintain this superiority when rearing multiple lambs. To improve weight and condition of Merino ewes during the ‘tough’ times, when nutrient requirements are not met by the pasture, selection can be made at any time and this will result in increased genetic condition at all times.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/AN13248
Abstract: The success of slaughter lamb enterprises is heavily influenced by the ability of the breeding ewe to produce a lamb annually across variable environments. It has been shown that by maintaining heavier weight and condition across the annual production cycle producers can make significant improvements in maternal performance. This paper follows on from a previous analysis of crossbred ewes within the Maternal Central Progeny Test and examines the potential to select for reduced fluctuation in weight and fat across the production cycle. A cubic spline model was fitted to the weight and fat score data from the first three parities of 2688 first-cross ewes. The analysis partitioned the influence of environment, reproduction and genetic effects on the shape of the weight and fat score splines across three parities. Yearly and seasonal variation in feed supply and the demands of raising a lamb are the major influences on fluctuations in the weight and fat score of the breeding ewe. The genetic effects were constant across time with 98 and 92% of the genetic variation for weight and fat, respectively, associated with the spline’s intercept. In agreement with the findings of the first paper of the series it can be concluded that genetic lines do not re-rank for weight or fat score over time. The influence of sire breed on weight and fat score was constant across time with sire breeds fluctuating in parallel across time. As a result it is concluded that to avoid low fat reserves and the subsequent low fertility during the ‘tough’ periods, selection to improve ewe body condition could be made at any time and under any environmental conditions.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN14579
Abstract: In southern Australian grazing systems, energy availability typically exceeds energy requirements. Grazing systems are likely to have higher profitability if ewes can utilise this relatively cheap feed by gaining more condition (muscle and fat) and then mobilising it when feed is expensive. The present paper focusses on the importance of genetic merit for fat on the lifetime productivity of the ewe within a commercial operation. The analysis was carried out on a maternal composite stud flock in Holbrook, New South Wales. Ultrasound fat and muscle depth were measured on 2796 ewes as lambs at post-weaning and as adult ewes, to determine the genetic relationship between young and adult body composition. The hypothesis of the paper is that selection for increased fat at young age will improve body condition of adult ewes, which will lead to improved reproduction and potentially reduced requirements for supplementary feeding. Given that the difference in feed cost between times of abundance and shortage is likely to be larger, the system may become more profitable despite being less efficient (owing to increased feed intake). Our results indicated that selection for scanned post-weaning fat and muscle depth in lambs should lead to increased fat muscle and body condition in the breeding ewe because of strong genetic correlation estimates between the post-weaning and adult traits of 0.68–0.99. The influence of body composition traits on reproduction (number of lambs weaned) within the stud flock was weak. However, it is hypothesised that by genetically increasing post-weaning fat depth in ewes, producers could improve profitability by reducing the demands for supplementary feeding.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/ANV58N1_FO
Publisher: Wiley
Date: 17-03-2004
Publisher: Wiley
Date: 22-04-2001
DOI: 10.1046/J.1365-2052.2001.00728.X
Abstract: The results of genotypic data contributed to the International Society of Animal Genetics (ISAG) Bovine Chromosome 11 (BTA11) Workshop are presented. Six laboratories contributed a total of 26 199 informative meioses from 80 loci. Thirty-six loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of the chromosome. The remaining loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 128.9 cM. The female consensus map was 101.2 cM, while the male consensus map was 129.8 cM. The comprehensive sex-averaged map was 134.2 cM and the average genetic distance between loci was 1.72 cM.
Publisher: Wiley
Date: 07-09-2021
DOI: 10.1111/AGE.13135
Abstract: The advent of high‐throughput chromosome conformation capture and sequencing (Hi‐C) has enabled researchers to probe the 3D architecture of the mammalian genome in a genome‐wide manner. Simultaneously, advances in epigenomic assays, such as chromatin immunoprecipitation and sequencing (ChIP‐seq) and DNase‐seq, have enabled researchers to study cis ‐regulatory interactions and chromatin accessibility across the same genome‐wide scale. The use of these data has revealed many unique insights into gene regulation and disease pathomechanisms in several model organisms. With the advent of these high‐throughput sequencing technologies, there has been an ever‐increasing number of datasets available for study however, this is often limited to model organisms. Livestock species play critical roles in the economies of developing and developed nations alike. Despite this, they are greatly underrepresented in the 3D genomics space Hi‐C and related technologies have the potential to revolutionise livestock breeding by enabling a more comprehensive understanding of how production traits are controlled. The growth in human and model organism Hi‐C data has seen a surge in the availability of computational tools for use in 3D genomics, with some tools using machine learning techniques to predict features and improve dataset quality. In this review, we provide an overview of the 3D genome and discuss the status of 3D genomics in livestock before delving into advancing the field by drawing inspiration from research in human and mouse. We end by offering future directions for livestock research in the field of 3D genomics.
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/EA05248
Abstract: During a 4-year period (1994–97) of the Australian ‘Southern Crossbreeding Project’, mature Hereford cows (n = 637) were mated to 97 sires from 7 breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue), resulting in 1334 calves. Heifers were slaughtered at around 16 months and steers at 23 months. The objective of the study was to quantify between- and within-breed genetic variation for numerous production and quality traits in a southern-Australian production system. Calf survival, birth weight and carcass production traits (carcass weight, fat depth, loin eye area, intramuscular fat) were obtained from these cattle. The carcass traits were loge-transformed because of a scale effect on the variance. Data were analysed using multi-variate animal models containing fixed effects of sex with random effects of management group, sire breed and animal. In addition, birth month and age of dam were included as fixed effects for birth weight. Covariances between survival and other traits could not be estimated from the multi-variate model so they were estimated from a series of bi-variate models. On average, management group and sire breed accounted for similar proportions of variance. Heritability ranged from 0.14 (survival), 0.17 (intramuscular fat), 0.28 (loin eye area), 0.29 (P8 fat depth), 0.31 (birth weight) to 0.50 (carcass weight). In general, environmental (management and residual) correlations between meat (carcass weight and loin eye area) and fat traits (fat depth and intramuscular fat) were positive, but the genetic correlations (both between and within breed) were negative. Management and genetic (co)variation has been quantified and can facilitate production of calves with carcasses suitable for specific market requirements.
Publisher: CSIRO Publishing
Date: 30-08-2021
DOI: 10.1071/AN21100
Abstract: Context Overseas studies have quantified production differences of Hereford × Angus compared with purebred Angus for a range of traits including growth, carcass and reproductive traits. Aim This study aims to provide a comparison of Hereford × Angus and purebred Angus under modern grazing conditions in southern Australia. Methods Thirty Hereford and 22 Angus sires were mated to 1100 Angus cows and heifers in a large commercial herd run on pasture at Musselroe Bay, Tasmania. Approximately 1650 calves were born. Steers were grown on pasture for an average of 23 months and then slaughtered. Results Hereford sired calves were heavier at birth (+8.8%) and weaning (+4.1%). Hereford-sired calves from heifers (but not from mature cows) had more assisted births (+8.2%) and more calf deaths (10.0% vs 5.1%). Hereford-sired steers had higher hot standard carcass weight (+4.1%) and eye-muscle area (+3.2%) but when hot standard carcass weight was fitted as a covariate, eye-muscle area was no longer significant. Carcass quality measures (AUSMEAT marbling –25.8%, Meat Standards Australia marbling –10.5%, Meat Standards Australia index –1.0%) were poorer for Hereford-sired steers and fat colour (+6.9%) was darker. Meat s les from Hereford-sired steers had significantly lower colour indicators (L and b). There was no difference in cooking loss and shear force, and intramuscular fat was lower (3.0% vs 4.1%). Conclusions Hereford × Angus calves were heavier at birth than were purebred Angus, but had more calving difficulty and deaths associated with heifer dams. Hereford × Angus carcasses were heavier but had lower indicators of quality than did purebred Angus. Implications As Hereford × Angus steers produced a 4.1% heavier carcass, pure Angus steers would need to attract a premium of at least 4.1% for the additional marbling to give more value. Hereford bulls could be mated to Angus cows and not Angus heifers to avoid calving difficulties. Alternatively, good calving Hereford bulls could be selected using estimated breeding values when mating to Angus heifers.
No related grants have been discovered for Wayne Pitchford.