ORCID Profile
0000-0002-0700-7585
Current Organisation
University of Adelaide
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Publisher: Cold Spring Harbor Laboratory
Date: 13-05-2019
DOI: 10.1101/634717
Abstract: Tongue-ties (TT) are commonly applied to both Standardbred and Thoroughbred racehorses to increase control, by preventing them from getting their tongue over the bit, and as a conservative treatment for equine respiratory conditions, principally dorsal displacement of the soft palate. This study investigated responses to TT application in horses, at rest, using both behavioural (head-tossing, ear position, gaping and lip licking) and physiological (salivary cortisol concentrations, eye surface temperature and heart rate) indices. Twelve Standardbred horses (six of which were naïve to TT) were used in a randomised crossover design. The study comprised 3 phases Phase 1 (Baseline), Phase 2 (Treatment), and Phase 3 (Recovery). At phase 2, tongue tie application (TTA) was performed using a rubber band that was looped around the tongue and secured to the mandible for 20 minutes. The control treatment (C) incorporated 30 secs of tongue manipulation, at the start of the 20 min, however no TT was applied. Behaviours (head-tossing, ear position, mouth gaping and lip-licking) and heart rate (HR) were recorded for the duration of the study and analysed in ten minute intervals. Salivary s les were taken at the end of each phase for subsequent cortisol assays and infrared thermography images were taken of each eye at 5-minute intervals. Statistical analyses were performed in SPSS using linear mixed effects models and repeated measures general linear models, to determine differences between treatments and within treatments, over time. Compared to control, there was more head-tossing/shaking (p .001), gaping (p .001) and backwards ear position (p .001) and less forward ear position (p .001) during TTA, in Phase 2. Horses with previous experience of TT showed more head-tossing (p=0.040) and gaping (p=0.030) than naïve horses. Lip-licking was more frequent after TTA treatment than control, during Phase 3 (p .001). Salivary cortisol concentrations increased after TTA (1846.1pg/mL ± 478.3pg/mL vs 1253.6pg/mL ± 491.6pg/mL, p=0.047). Mean HR, and mean right and left eye temperature did not differ significantly between treatments in any phase (all p 0.05). The findings of this study suggest the application of a tongue-tie causes changes to both behavioural and physiological parameters suggestive of a stress-related response. Further research is needed that will enable racing and sport horse regulatory bodies to make informed decisions about the appropriate use of tongue-ties in horses.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/AN13140
Abstract: Poor lamb survival pre-weaning is a major source of reproductive inefficiency in Australian sheep flocks. While nutrition and management options have been extensively researched and promoted to improve lamb survival, the present review focuses on the prospects for obtaining genetic gain and helps identify selection strategies for boosting such gains to improve overall reproductive efficiency in the Australian sheep industry. Estimated heritability for lamb survival using linear model analysis is low, although use of threshold models suggests that heritability could be higher, which, if true, could help explain the substantial genetic gains obtained in long-term selection experiments. Epigenetic mechanisms may hinder selection and quantitative trait-loci identification through confounding and/or masking genetic variances and co-variances. With sufficient information, these effects could be considered in genetic evaluations by identifying those components that are amenable to selection. Regarding indirect selection, finding effective criteria for improving lamb survival has proved elusive. Most measures of maternal behaviour, temperament and lambing difficulty researched are poorly correlated genetically with lamb survival. Of lamb behaviours and thermo-genic indicators studied, latency to bleat following handling by humans is moderately genetically correlated with lamb survival, as is neonatal rectal temperature. Industry application remains to be adequately explored for the more promising of these measures. Finally, in lieu of direct selection for lamb survival, there is merit in selecting for multiple-rearing ability or its equivalent, possibly with additional selection criteria for lamb survival and reproductive efficiency.
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/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: American Physiological Society
Date: 02-2008
DOI: 10.1152/AJPENDO.00409.2007
Abstract: Despite the well-known benefits of omega-3 ( n-3) polyunsaturated fatty acid (PUFA) supplementation on human health, relatively little is known about the effect of n-3 PUFA intake on fertility. More specifically, the aim of this study was to determine how oocyte and preimplantation embryo development might be influenced by n-3 PUFA supply and to understand the possible mechanisms underlying these effects. Adult female mice were fed a control diet or a diet relatively high in the long-chain n-3 PUFAs for 4 wk, and ovulated oocytes or zygotes were collected after gonadotropin stimulation. Oocytes were examined for mitochondrial parameters (active mitochondrial distribution, mitochondrial calcium and membrane potential) and oxidative stress, and embryo developmental ability was assessed at the blastocyst stage following 1) in vitro fertilization (IVF) or 2) culture of in vivo-derived zygotes. This study demonstrated that exposure of the oocyte during maturation in the ovary to an environment high in n-3 PUFA resulted in altered mitochondrial distribution and calcium levels and increased production of reactive oxygen species. Despite normal fertilization and development in vitro following IVF, the exposure of oocytes to an environment high in n-3 PUFA during in vivo fertilization adversely affected the morphological appearance of the embryo and decreased developmental ability to the blastocyst stage. This study suggests that high maternal dietary n-3 PUFA exposure periconception reduces normal embryo development in the mouse and is associated with perturbed mitochondrial metabolism, raising questions regarding supplementation with n-3 PUFAs during this period of time.
Publisher: Wiley
Date: 26-09-2017
DOI: 10.1111/AVJ.12636
Abstract: To measure the prevalence of internal tandem duplications (ITDs) in exon 11 of the proto-oncogene C-KIT in a s le of Australian cutaneous canine mast cell tumours (MCTs) drawn from general practice and to evaluate relationships between tumour mutation status and prognostic factors including signalment, tumour histological grade, tumour anatomical location and tumour size. C-KIT exon 11 ITDs were detected by PCR in DNA extracted from formalin-fixed, paraffin-embedded canine MCTs sourced from three veterinary diagnostic laboratories in Adelaide and Melbourne. Tumours were graded according to two different systems (Patnaik and Kiupel systems) by board-certified anatomical pathologists blinded to the PCR results. Relationships between tumour mutation status and prognostic factors were evaluated using a generalised binary logistic regression analysis. ITDs were identified in 13 of 74 cutaneous canine MCT s les, giving an overall prevalence of 17.6% (95% confidence interval: 8.9-26.2%). ITDs were detected in 10 of 18 Patnaik grade III MCTs (55.6%) and 11 of 22 Kiupel high-grade MCTs (50%). Wald chi-square analysis revealed that detection of tumour ITDs was significantly associated with both Patnaik's and Kiupel's histologic grading systems (each: P < 0.001). The presence of the ITDs in MCTs was not associated with signalment, tumour anatomical location or tumour size. The prevalence of C-KIT exon 11 ITDs in Australian canine MCTs is similar to the prevalence in overseas canine populations (overall prevalence in Australia approximately 18%). ITDs were more frequently identified in higher grade MCTs.
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: MDPI AG
Date: 25-10-2022
DOI: 10.3390/ANI12212918
Abstract: Media portrayals of animal cruelty can shape public understanding and perception of animal welfare law. Given that animal welfare law in Australia is guided partially by ‘community expectations’, the media might indirectly be influencing recent reform efforts to amend maximum penalties in Australia, through guiding and shaping public opinion. This paper reports on Australian news articles which refer to penalties for animal cruelty published between 1 June 2019 and 1 December 2019. Using the electronic database Newsbank, a total of 71 news articles were included for thematic analysis. Three contrasting themes were identified: (1) laws are not good enough (2) laws are improving and (3) reforms are unnecessary. We propose a penalty reform cycle to represent the relationship between themes one and two, and ‘community expectations’. The cycle is as follows: media reports on recent amendments imply that ‘laws are improving’ (theme two). Due to a range of inherent factors in the criminal justice system, harsher sentences are not handed down by the courts, resulting in media report of ‘lenient sentencing’ (theme one). Hence, the public become displeased with the penal system, forming the ‘community expectations’, which then fuel future reform efforts. Thus, the cycle continues.
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: 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: Elsevier BV
Date: 2009
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/AR06327
Abstract: The development of the follicle population in Merino sheep skin was studied from 30 days pre-partum to 112 days post-partum in single- and twin-born Merino lambs. The total number of primary follicles estimated from primary follicle density and skin surface area did not change over this period, while secondary follicle number increased to Day 28 post-partum in singles and Day 56 post-partum in twins. Twins had 14% fewer total follicles than singletons (P 0.001), largely reflecting a bodyweight (hence estimated skin surface area) difference of 10%, with little difference in total follicle density (P 0.05). Immediately post-partum there was a 36% decrease (P 0.0001) in the secondary to primary follicle ratio (S/P) of the twin lambs, while a small non-significant decrease (7% P 0.05) occurred in the single lambs. This attrition coincided with a surge in plasma cortisol concentration that commenced ~12 days before birth and persisted for 6–12 days post-partum. The surge in plasma cortisol concentration occurred in both single and twin lambs, commencing on Day 138 of gestation however, the peak cortisol concentration and the period over which cortisol remained elevated was greater in twin lambs than in singletons (P 0.001). This study confirms a previous finding of a perinatal reduction in S/P ratio in Merino sheep. The reduction was greater in twin lambs than in singletons but the follicles of twins recovered rapidly so that there was little difference in final S/P ratio between birth types after Day 30 post-partum. The postnatal follicle reduction followed the perinatal surge in plasma cortisol concentration and appeared to reflect the magnitude of the cortisol surge in that twins, which displayed a higher peak cortisol concentration, had a greater reduction in active follicles than singletons.
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.PREVETMED.2019.104714
Abstract: Although dogs routinely travel in motor vehicles, there is a lack of evidence on if, how, and why people choose to restrain their dogs when travelling. A lack of restraint is likely to be associated with an increased risk of serious injury or death in the case of an accident, and in some cases may even precipitate an accident. The aim of the present study was to determine the frequency in which dog restraints are used in the US, UK and Australia in a convenience s le, and the factors associated with whether or not a dog is restrained. Online surveys using SurveyMonkey® were distributed in the US, UK and Australia during 2017-2018. The survey consisted of questions related to owning a dog, owner and dog demographics, use of restraint when driving with the dog, reasons for restraining/not restraining the dog, and attitudes to restraint of dogs in vehicles. A logistic regression was used to determine factors associated with the use of restraint. There were 706, 692 and 637 completed surveys from the US, UK and Australia, respectively. A little over half of respondents restrained their dog in the US (55%) compared to 67% in Australia and 72% in the UK. The most common method of restraint in the US and UK was a cage/crate in the cargo area in the back of the vehicle in Australia it was a harness and tether attached to a seat buckle. In the generalised linear model, country, dog size, owner age, dog age and vehicle type were all significant factors associated with the use of restraint for dogs in cars. Younger dog owners from the US who drove a pickup truck or utility van, had a large dog, and drove with their dogs less frequently were least likely to restrain their dogs. This research highlights the need for improved education and information regarding the use of restraints for dogs traveling in vehicles, although the limitations in the convenience s le used mean further research is needed, including use of a more representative s le.
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: 2021
DOI: 10.1071/AN20149
Abstract: Context Ecchymosis is an undesirable appearance in meat caused by small bleeds from capillaries broken during the slaughter process. These lesions are heavily trimmed during processing, incurring labour costs and yield losses. Aims To estimate the prevalence of ecchymosis in a South Australian abattoir and investigate potential predisposing factors. Methods A generalised linear mixed model estimated the effects of breed, age, slaughter shift (morning or afternoon), kill date, direct or market consignment, hot standard carcase weight (HSCW, kg), deviation from lot average carcase weight (ZHSCW, standard units), palpated fat score (mm) and time in lairage (h) on the prevalence of ecchymosis. Over 7 days, 12286 lamb and 3802 mutton carcases from 82 properties were scored (0, 1) for ecchymosis. Key results Lambs had a higher prevalence of ecchymosis (14%) than did mutton (1% P & 0.001), with significant variation between lines of lambs (P & 0.001). Considering lambs only, kill date (P & 0.01), time in lairage (P & 0.001), and the quadratic terms of HSCW (P & 0.001) and ZHSCW (P & 0.01) affected the prevalence of ecchymosis. Conclusions Ecchymosis had a significant prevalence in lambs only. The time lambs spend in lairage and their bodyweight may be predisposing factors for ecchymosis before slaughter and warrant further investigation. Implications The interaction of size and weight extremeness appeared to predispose lambs to developing ecchymosis at slaughter. Farm of origin was another identified risk factor (management group). Whether it was size and extremeness influencing body composition or other mechanisms involved in vascular integrity, is not known. Further research is required to identify these mechanisms so as to establish breeding and management guidelines that will decrease the likelihood and cost of ecchymosis in lambs. Ecchymosis remains poorly understood, but fractured capillaries indicate a weakness in vascular tissue. Given the present study included over 12000 observations in 7 days, ecchymosis in lambs could be used as a model to study vascular weakness in humans.
Publisher: Wiley
Date: 12-08-2021
DOI: 10.1111/AVJ.13111
Abstract: A sustainable workforce is important for the veterinary profession to meet the demands of society. To maintain a sustainable workforce, it has been recommended to retain veterinary clinicians. However, there seems to be an increasing issue with retention of veterinarians in clinical practice. In the following study, the researchers sought to understand the associations between demographic and work‐related factors and attrition of veterinarians from clinical practice. Responses to an online cross‐sectional survey of 881 current and former Australian veterinary clinicians were analysed. A logistic regression model was used to identify and describe associations between attrition from veterinary clinical practice and salary, working hours, role in practice, years of experience, field of work, interaction with regulatory authorities, region of work and on‐call duties. Lower salary, longer working hours, having on‐call duties and having worked in both rural and metropolitan regions were found to significantly (P 0.05) increase the likelihood of leaving clinical practice. The results may inform intervention strategies to assist the industry to retain veterinarians in clinical practice.
Publisher: MDPI AG
Date: 12-11-2019
DOI: 10.3390/ANI9110957
Abstract: There are conflicting reports regarding the effect of farrowing house accommodation on piglet performance. The aim of this investigation was to use a systematic review and meta-analyses to summarise the results of publications that focused on direct comparisons between full confinement conventional crates and various designs of loose-housed farrowing pens from loading until weaning. Literature searches in Scopus, BIOSIS Previews, Cab Abstracts, and Web of Science identified 6695 articles. Twenty-two publications were retained for the systematic review and in idual meta-analyses after screening for inclusion criteria. The random effects meta-analyses were performed on crate versus pen for number of piglets born alive, number of stillborn piglets, pre-weaning mortality, and number of piglets weaned. Additionally, the modifiers of confinement length (no confinement from loading until weaning or partial confinement for shorter periods of time in the early stages post parturition), enrichment (no enrichment or enrichment provided), and pen size (small, medium, or large) were examined. There was a 14% increase in the relative risk of piglet mortality in farrowing pens when they were compared with crates (p = 0.0015). The number of stillborns per litter was not different between the pen and crate. However, when providing enrichment in the pens, there was an increase in stillborns within farrowing crates versus pens (p = 0.009). There was no overall effect on piglets that were born alive or number weaned. As there is no difference between piglets born alive and mortality is significantly higher in farrowing pens, a reduction in the number of piglets weaned was expected but not observed, which was possibly due to the lack of weaning details provided in the publications. This was the first systematic review and meta-analysis conducted on the performance of farrowing accommodation and identified that farrowing pens do compromise post-natal piglet survival. Future efforts should focus on improving sow comfort in the farrowing crate to maximize both piglet and sow welfare.
Publisher: MDPI AG
Date: 13-03-2020
DOI: 10.3390/ANI10030482
Abstract: Previous research has identified a number of issues arising at all stages of the animal law enforcement process. These issues contribute to an enforcement gap between the written law, as it relates to the penalties laid out in statutes, and the reality of the animal law justice system. This paper identifies and investigates the contributors to this gap. The identified factors discussed are (1) the role of the public in reporting animal cruelty, (2) the ambiguity of the language used in animal welfare legislation, (3) the nature of enforcement authorities, and (4) the role of the courts. Thus, the causes of the enforcement gap are multifactorial, derived from all stages of the enforcement process. Further research on the enforcement model and public education, in addition to debate on legislative reforms, will be needed to address this gap.
Publisher: MDPI AG
Date: 08-12-2018
DOI: 10.3390/ANI8120236
Abstract: Animal welfare legislation in South Australia underwent amendments in 2008, where all the maximum penalties for animal welfare offences were doubled. This commitment to increased penalties arguably provides evidence of the legislature’s intent with respect to penalties. Studies have speculated that the legislative intent behind the increased penalties is not being reflected in the courts. This interdisciplinary research sought to gain evidence to confirm or disprove these speculations, by quantifying the average custodial sentence and monetary fine handed down in court before and after the 2008 amendments. Furthermore, trends relating to the species of animal affected and the demographics of the offender were identified. A total of 314 RSPCA (SA) closed case files from 2006 to 2018 were converted into an electronic form. Since the amendments, the average penalties have doubled in magnitude fines have increased from $700 to $1535, while prison sentences have increased from 37 days to 77 days. Cases of companion animal abuse were most common (75% of all cases) and the location of the offence was found to influence offending. These findings suggest that the 2008 amendments have caused the average penalties to increase. However, it is debatable whether these increases are enough to effectively punish animal abusers.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN15099
Abstract: Lamb mortality represents reproductive wastage and an animal welfare concern. While lambs are thought to be at a thermogenic advantage following birth in comparison to other species, death from exposure can still be a major contributor to lamb mortality, largely because of the inclement conditions often prevailing at lambing. For this reason, thermogenesis has been studied extensively in neonatal lambs. Heat is produced in the neonatal lamb by shivering and non-shivering thermogenesis. The latter is heat generated by metabolism of brown adipose tissue (BAT) found largely in the thorax and peri-renal areas of the newborn lamb. Brown adipose tissue differs from normal adipose tissue in that it contains densely packed mitochondria, a high cytochrome c content and a vast vascular network. Heat is generated in BAT by uncoupling of the proton conductance mechanism from ATP production, resulting in heat production instead of stored energy. The ability of lambs to resist cooling differs among in iduals and this is likely to be due to both genetic and phenotypic factors. The heritability of cold resistance is moderate-to-high and polymorphic gene markers associated with energy homeostasis and cold-related mortality have been identified. Additionally, several aspects of the phenotype of the lamb have been associated with cold resistance. Most relate to properties of the coat, skin and bodyweight, the latter being particularly important, presumably through effects on surface area to volume ratios and subsequent heat loss. The ability of the neonate to achieve the transition from intra- to extra-uterine life has been termed physiological maturity and is associated with the ability to activate appropriate neuro-endocrinological and behavioural changes that are consistent with homeostasis of energy metabolism. Ways to alter physiological maturity of the lamb, such as nutrition, pharmacology and genetic selection, have been identified, and while these show promising results with regards to thermoregulation, a key limitation of their application has been the lack of a repeatable, representative model of neonatal cold stress. An estimation of the non-shivering component potential of a lamb’s ability to thermoregulate can be derived from norepinephrine challenges, but more useful models of real-world cold stress are climate chambers or controlled water bath tests. Further use of repeatable test models such as these with appropriate neuroendocrine and metabolic metrics will identify key components and markers of physiological maturity associated with lamb thermogenesis and survival.
Publisher: Public Library of Science (PLoS)
Date: 27-01-2020
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: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN14957
Abstract: Ability to adapt rapidly from the uterine environment to self-thermoregulation following birth is a vital requirement for neonatal lamb survival. This investigation reports factors that could explain differences in thermoregulation among breeds that differ in lamb survival. Breeds such as the Merino and Border Leicester have previously been shown to be ergent for birthweight, cold resistance and lamb survival. Cross-bred (Poll Dorset Border Leicester (PDBL, n = 9) and Poll Dorset Merino (PDM, n = 25)) and pure-bred (Border Leicester (BL, n = 35) and Merino (M, n = 46)) lambs were recorded for the thermogenic measures rectal temperature at birth, cold resistance (time for rectal temperature to fall to 35°C while in a cooled water bath) and cold recovery (time to restore rectal temperature after cold exposure) at 1 day of age. In pure-bred lambs, 1 kg increase in weight resulted in a 0.25°C increase in rectal temperature at birth (P 0.001) and 4.2 min increase in cold resistance (P 0.001). In contrast, cross-bred lambs did not exhibit any relationship between birthweight and rectal temperature at birth, although they displayed a 3.2 min greater cold resistance for every 1 kg increase in birthweight (P 0.001). BL-derived lambs were more cold resistant than M lambs (cross-bred: PDBL, 67.1 ± 2.5 min PDM, 56.4 ± 1.6 min P 0.01 and pure-bred: BL, 58.1 ± 1.5 min M, 53.2 ± 1.3 min P 0.01). The quadratic relationship of glucose concentration over time during cold exposure differed with lamb breed. PDBL exhibited higher peak glucose concentrations than did PDM (11.0 mmol/L and 8.9 mmol/L, respectively P 0.01). BL took longer to reach peak glucose concentration (50 min) than did M (40 min) and this peak value was higher (BL, 9.4 mmol/L M, 7.7 mmol/L P 0.001). In conclusion, variations in birthweight and glucose metabolism are associated with breed differences in thermogenesis of neonatal lambs.
Publisher: Elsevier BV
Date: 05-2023
Publisher: MDPI AG
Date: 26-12-2020
DOI: 10.3390/ANI11010035
Abstract: Animal welfare is not included in the Australian Constitution, rendering it a residual power of the states and territories. Commentators have suggested that inconsistencies exist between the state and territory statutes, and that a uniform approach would be beneficial. However, there has been no comprehensive assessment of the nature or extent of these purported inconsistencies. This review addresses this gap by providing a state-by-state comparison of animal protection statutes based on key provisions. Utilizing systematic review methodology, every current Australian statute with an enforceable protection provision relating to animal welfare was identified. A total of 436 statutes were examined, with 42 statutes being included in the detailed analysis. The comparison showed that animal protection laws are generally consistent between each Australian jurisdiction and were found to have similar shortcomings, notably including lack of a consistent definition of ‘animal’ and reliance on forms of legal punishment to promote animal welfare which have questionable effectiveness. It is argued that there is a need for attention to definitions of key terms and future consideration of alternative forms of penalties, but that a uniform federal approach may not be necessary to address these shortcomings.
Publisher: Elsevier BV
Date: 11-2011
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: Elsevier BV
Date: 08-2021
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: 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: 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: 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: Brill | Wageningen Academic
Date: 2005
Publisher: MDPI AG
Date: 16-03-2023
DOI: 10.3390/ANI13061070
Abstract: P wave indices are used as non-invasive electrocardiographic markers of atrial remodelling in humans. Few studies have investigated their use in animals. The aim of this study was to measure P wave duration and P wave dispersion (Pd) in healthy standardbred horses and investigate variables that might influence these measurements. A 12-lead electrocardiogram was recorded at rest and P wave indices were calculated in 53 horses. A general linear model was used to investigate the main effects: age, bodyweight, sex, resting heart rate, presence of a murmur, exercise status and the number of years raced. There were significant associations with exercise status for both the maximum P wave duration and Pd, with both values being increased in strenuously exercising versus non-active horses. Furthermore, a significant moderate positive correlation was identified between the duration of exercise (number of years raced) and both Pmax and Pd. No other significant associations were identified. These findings are similar to those reported in elite human athletes versus sedentary in iduals. The increases in these P wave indices most likely occur due to prolongation and heterogeneity in atrial conduction time, which are associated with structural and electrical remodelling, and may explain the increased risk of atrial fibrillation in athletic horses.
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: CSIRO Publishing
Date: 2004
DOI: 10.1071/EA02109
Abstract: The effect of missing feed intake records on the estimate of feed intake in cattle over a 70-day test period was studied. Two datasets, containing several cattle breeds at different ages, were analysed. The first dataset comprised 300-day-old Angus cattle, while the second dataset consisted of 900-day-old Limousin and Jersey crossbred cattle. A first-, second- and third-order polynomial and a non-linear function were fitted to the intake data. The 3 polynomial functions showed minimal differences in their goodness of fit to the data, with the non-linear function explaining the least variation in intake. Both datasets were analysed over a 70-day test period and shortened tests were compared to the full 70-day test. Tests were shortened by randomly deleting intake records or periodically deleting data on a daily or weekly basis. The effect of missing data on feed intake estimates was evaluated using Pearsons correlation and t-tests. The results suggest that a greater proportion of data can be removed randomly and daily, compared with missing data in weekly blocks. However, when data are removed in weekly blocks, removal in the middle of the test period gives a more accurate estimate of feed intake. It appears that in young growing animals, estimation of daily feed intake is more sensitive to missing feed intake records than for older cattle.
Publisher: Elsevier BV
Date: 2020
Publisher: Oxford University Press (OUP)
Date: 27-07-2018
DOI: 10.1093/JAS/SKY248
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/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/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: MDPI AG
Date: 09-07-2021
DOI: 10.3390/ANI11072054
Abstract: The ability to assess the welfare of animals is dependent on our ability to accurately determine their emotional (affective) state, with particular emphasis being placed on the identification of positive emotions. The challenge remains that current physiological and behavioral indices are either unable to distinguish between positive and negative emotional states, or they are simply not suitable for a production environment. Therefore, the development of novel measures of animal emotion is a necessity. Here we investigated the efficacy of microRNA (miRNA) in the brain and blood as biomarkers of emotional state in the pig. Female Large White × Landrace pigs (n = 24) were selected at weaning and trained to perform a judgment bias test (JBT), before being exposed for 5 weeks to either enriched (n = 12) or barren housing (n = 12) conditions. Pigs were tested on the JBT once prior to treatment, and immediately following treatment. MiRNA and neurotransmitters were analyzed in blood and brain tissue after euthanasia. Treatment had no effect on the outcomes of the JBT. There was also no effect of treatment on miRNA expression in blood or the brain (FDR p 0.05). However, pigs exposed to enriched housing had elevated dopamine within the striatum compared to pigs in barren housing (p = 0.02). The results imply that either (a) miRNAs are not likely to be valid biomarkers of a positive affective state, at least under the type of conditions employed in this study, or (b) that the study design used to modify affective state was not able to create differential affective states, and therefore establish the validity of miRNA as biomarkers.
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/EA08150
Abstract: The potential for adopting a genetic solution to protect sheep from blowfly strike on the breech was investigated in a flock of sheep that contained several animals expressing a trait characterised by low wool coverage over the breech and through a wide channel from the anus to the udder or scrotum. A scoring system (1, bare to 5, woolly) was developed and used to determine the heritability of the trait and its phenotypic and genetic correlations with other traits of importance in a sheep enterprise. In comparison to animals with woolly breeches, the skin in the breech of animals with a low bareness score was characterised by a low density of follicles producing short, medullated fibres, with histological evidence of immune rejection and follicular atrophy. The bareness score of progeny was influenced by the score of their respective sires suggesting a strong genetic component. The heritability of bareness score was moderate to high (h2 = 0.45 ± 0.02, 0.53 ± 0.01 and 0.38 ± 0.02 at lamb, hogget and adult ages, respectively). The lactation status and age of ewes influenced their bareness score, resulting in a low repeatability (0.42) of the trait between ages in females. Genetic correlations between bareness score and most other economically important traits were low. The weight of belly wool and the weight of skirtings was genetically related to bareness score (rg = +0.52 and +0.48 respectively), indicating that animals with barer breeches tend genetically towards lighter belly wool weights and lower weight of skirtings at wool classing. Selection and breeding for bareness score should achieve relatively rapid progress towards fixing the trait in a flock and without adverse effects on other important traits. Caution should be exercised in extrapolating these results to other bloodlines and environments where genetic mechanisms or environmental influences may be different.
Publisher: MDPI AG
Date: 14-05-2018
DOI: 10.3390/ANI8050074
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: 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.
Publisher: CSIRO Publishing
Date: 24-08-2021
DOI: 10.1071/AN21101
Abstract: Context Despite the increased economic importance of reproductive rate in Australian Merinos, there have been low genetic improvements in reproductive performance over the past several decades. Genetically improving reproductive traits through direct selection is restricted by low heritability, low selection intensity directly on reproductive traits, high recording costs and lack of accurate maternal pedigrees in the majority of industry breeding programs. However, indirect selection via correlated traits may be useful as a supplement to direct selection or even on its own where reproduction records are not collected. Aims The aims of the present study were to determine whether various production and quality traits have the potential to be used as indirect selection criteria for genetically improving lifetime reproductive rate, but also whether their selection could be detrimental to reproduction via unfavourable correlations. Methods Reproductive traits studied included pregnancy rate (ewes scanned pregnant per ewe joined), fetal number (number of fetuses scanned per ewe joined), number of lambs born (per ewe joined), number of lambs weaned (per ewe joined) and ewe rearing ability (number of lambs weaned per fetuses scanned). Using data from the SA Selection Demonstration Flocks project (1997–2005), reproductive traits were modelled against various visual and production traits to estimate correlations. Key results Favourable genetic correlations with reproductive traits were estimated with adult ewe bodyweight (0.37–0.50), hogget eye muscle depth (HEMD, 0.40–0.57), fat depth (HFAT, 0.27–0.48) and hogget body (HBWS) and neck wrinkle scores (–0.13 to –0.50). However, the estimates for genetic correlations with hogget eye muscle depth and fat depth were lower when bodyweight was fitted as a covariate, being 0.11–0.35 and 0.17–0.32 respectively. Genetic correlations with ewe rearing ability were generally unfavourable (except those with hogget body and neck wrinkle scores, which were –0.24 and –0.15 respectively), but were either negligible (adult ewe bodyweight, hogget eye muscle depth, fibre diameter and fleece weight) or low in magnitude(fat depth). Unfavourable genetic correlations were observed between fibre diameter and reproductive traits (0.13–0.33). Fleece weight had negligible genetic correlations with all reproductive traits studied (–0.08 to 0.10). Predictions of response to index selection using indirect criteria of one or more of yearling weight, HBWS, HEMD and HFAT measurements projected substantial genetic gains in the number of lambs weaned per ewe joined (NLW). Without reproduction records on the dams of candidates for selection, indirect selection using all four indirect criteria (yearling weight, HBWS, HEMD and HFAT) was predicted to achieve 112–168% of the genetic gains of direct selection for NLW. When all indirect and direct criteria for NLW are combined as part of index selection, even larger gains for NLW are predicted (from 164–215% of direct NLW genetic gains). Conclusions Findings from the present study suggest that bodyweight, HEMD and HFAT and HBWS could be potentially beneficial as indirect selection criteria for lifetime reproductive rate. Selection for reduced fibre diameter is potentially detrimental to reproductive performance however, selection for improved fleece weight is unlikely to have any effect on genetic gain for reproductive traits. Implications Use of indirect selection for lifetime reproductive could allow for genetic gain when either used with or without the direct selection criteria of reproduction records.
No related grants have been discovered for Michelle Hebart.