ORCID Profile
0000-0002-1942-8539
Current Organisations
Flinders University
,
University of New England
,
University of Portsmouth
,
University of Tasmania
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Publisher: CSIRO Publishing
Date: 30-08-2021
DOI: 10.1071/AN21124
Abstract: Context Breech flystrike is a costly trait to measure. Industry investment into genetic solutions for breech flystrike has resulted in the availability of estimated breeding values for indicator traits, such as breech wrinkle, breech cover and dag. However, selection is based on indicator traits rather than breech flystrike itself, and genetic gains could be enhanced through genomic selection approaches. Aim This study investigated whether genomic approaches based on major genes, such as marker-assisted selection, or genomic selection based on genomic breeding values, would be the most efficient application of genomic information to enhance genetic gains for breech flystrike resistance. Methods The analysis comprised 1535 sheep of the Merino Breeding for Breech Flystrike Resistance Resource flocks from New South Wales and Western Australia with high density genotypes (actual and imputed). A genome-wide association study was conducted on breech flystrike and its indicator traits, namely, breech wrinkle, dag and breech cover. The study also estimated genomic breeding values and their accuracy. Key results The SNP associations found in this study did not point to the existence of few genes with major effects on breech flystrike resistance or its indicator traits. Throughout the genome, associations of small effect were found, which enabled the estimation of genomic breeding values. However, these were of low accuracy, as expected for the size of the dataset. Conclusion Genomic prediction of breeding values for breech flystrike resistance is a feasible tool for applying genomic technology in the Merino industry. Implications A reference population of appropriate size needs to be established for this difficult-to-measure trait, and a dispersed reference population could be an effective option.
Publisher: Proceedings of the National Academy of Sciences
Date: 26-05-2022
Abstract: For millennia, Aboriginal Australian peoples have used the extraordinary physicochemical properties of plant exudates from practical applications to cultural expression. We employ state-of-the-art spectroscopy to characterize the molecular compositions of well-preserved, native Australian plant exudates ( Xanthorrhoea , Callitris , Eucalyptus , and Acacia ) from a historic collection assembled over a century ago. This work demonstrates the benefits of X-ray Raman spectroscopy for the analysis of these complex natural systems. It provides key information for a broader understanding of their terpenoid, aromatic, phenolic, and polysaccharide composition and subsequent chemical classification. It complements Fourier-transform infrared and pyrolysis–gas chromatography–mass spectrometry by allowing bulk-sensitive analysis in a fully noninvasive manner and probes molecular features which remain silent in these commonly employed analyses.
Publisher: CSIRO Publishing
Date: 05-06-2023
DOI: 10.1071/AN23029
Abstract: An ability to describe the quality of lived experience across the course of an animal’s life is of increasing interest in studies on wellbeing in farm animals. Integrity of physical functions is an important aspect of the tripartite model of wellbeing: feeling, functioning and interacting well. This review examines measures of functional integrity as potential indicators of functional (eudaimonic) wellbeing. Copious literature shows that coping with day-to-day fluctuations in the environment influences (1) periodicity of biorhythms, (2) allocation of resources to growth, defence and repair, and (3) rate of biological aging. Here we review opportunities for assessing functional integrity through analysis of (1) the dynamic status of physiological and behavioural variables, (2) the accretion of resources in production tissues (milk, eggs, body mass, offspring) and physical structures (fibre, hoof, bone, tooth, placoid scale, otolith, beak), and (3) biological age. A reduction in periodicity of biorhythms, complexity of behaviours, or uniformity of trajectories of growth and production is often associated with poorer current and future health outcomes and shorter functional longevity. These analytical approaches are grounded in statistical measures of stability in complex dynamic systems. Additionally, the cumulative effect of wear and tear on biological age can be assessed via telomere length, DNA methylation, biomarkers of allostatic load, hair cortisol, and physiological functional capacity. Timeseries of behaviour, physiology and accretion provide a richer record of functional integrity than do cumulative indicators of biological age. Indicators of integrity are needed for each phase of the animal’s life course including attainment of developmental competencies, stability of mature performance, and rate of decline with advancing age, to provide a comprehensive record across the whole of the animal’s life. The utility of measures may differ between real-time and retrospective assessments and between application to every in idual versus sentinels. Further validation is required for interpretating measures of functional integrity as indicators of the functional aspect of wellbeing, together with determining their practicality and reliability before translation to commercial settings is feasible. A single type of indicator of functional wellbeing (e.g. DNA methylation) is unlikely to have utility for all life stages, species, production systems, and environments.
Publisher: Elsevier
Date: 2017
Publisher: Humana Press
Date: 2013
DOI: 10.1007/978-1-62703-447-0_2
Abstract: A good understanding of the design of an experiment and the observational data that have been collected as part of the experiment is a key pre-requisite for correct and meaningful preparation of field data for further analysis. In this chapter, I provide a guideline of how an understanding of the field data can be gained, preparation steps that arise as a consequence of the experimental or data structure, and how to fit a linear model to extract data for further analysis.
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/AN18383
Abstract: Context Knowledge of genetic and phenotypic variation and the accuracy of different measurement techniques is needed to successfully reduce livestock methane (CH4) emissions. Aims To estimate repeatabilities, heritabilities and genetic correlations of respiration-chamber (RC) and portable accumulation-chamber (PAC) measurements using two different protocols but the same management and feeding conditions. Methods Australian Information Nucleus Flock ewes were measured in seven test-batches. The 510 ewes were removed from pasture and habituated to chaffed alfalfa and cereal hay at 1.5–1.6 times maintenance. Methane was measured in RC for two 22-h periods approximately 14 days apart, and 40 min in PAC, either immediately after removal from in idual pens (with feed as described above, PAC0), or 1-h after withdrawing feed (PAC1). There were up to 48 PAC0 tests per day (at 0930 hours, 1100 hours, 1230 hours, 1400 hours in 12 PAC) and 24 PAC1 tests per day (at 1100 hours and 1300 hours). Test methods (RC, PAC0, PAC1) were analysed as different traits in a multi-trait repeated-measures model. Key results Before adjustment for liveweight (Lwt) or feed intake (FI), CH4 was highly repeatable (RC 78%, PAC0 83%, PAC1 82%), with heritabilities of 39–55%, permanent environmental (PE) animal variances 23–43% of phenotypic variances (Vp), high genetic correlations between methods (98–100%), and lower PE correlations (44–58%). A second PAC test on the same day decreased CH4 by 8–12% compared with the ewe’s first test that day. Heritabilities of FI from 0800 hours until the test was complete (FIOD) were 16–17% (PAC) and 25% (RC) before adjusting for Lwt, with high PE variances (PAC 67–73%, RC 41% of Vp). FI in the previous 24 h was highly heritable and much less variable than was FIOD in the RC, suggesting that testing introduced additional variation by disrupting feeding patterns. After adjusting CH4 for Lwt, FIOD and FI in the previous 24 h and Lwt, some additive genetic variation remained, averaging 17% of Vp. Multivariate models of CH4 and FI, fitting a single animal term (representing genetic+PE variation) showed high animal correlations between FI and CH4, namely, 90–95% before, and 86–95% after adjusting for Lwt. Conclusions PAC measurements are heritable and highly correlated with RC measurements under similar management conditions. The high genetic and animal correlations of PAC CH4 and FI imply that CH4 is a useful proxy for FI of grazing animals.
Publisher: Springer Science and Business Media LLC
Date: 27-08-2019
DOI: 10.1038/S41598-019-48861-3
Abstract: Acute exercise generally benefits memory but little research has examined how exercise affects metacognition (knowledge of memory performance). We show that a single bout of exercise can influence metacognition in paired-associate learning. Participants completed 30-min of moderate-intensity exercise before or after studying a series of word pairs ( cloud - ivory ), and completed cued-recall ( cloud -? Experiments 1 & 2) and recognition memory tests ( cloud -? spoon ivory drill choir Experiment 2). Participants made judgments of learning prior to cued-recall tests (JOLs predicted likelihood of recalling the second word of each pair when shown the first) and feeling-of-knowing judgments prior to recognition tests (FOK predicted likelihood of recognizing the second word from four alternatives). Compared to no-exercise control conditions, exercise before encoding enhanced cued-recall in Experiment 1 but not Experiment 2 and did not affect recognition. Exercise after encoding did not influence memory. In conditions where exercise did not benefit memory, it increased JOLs and FOK judgments relative to accuracy (Experiments 1 & 2) and impaired the relative accuracy of JOLs (ability to distinguish remembered from non-remembered items Experiment 2). Acute exercise seems to signal likely remembering this has implications for understanding the effects of exercise on metacognition, and for incorporating exercise into study routines.
Publisher: Informa UK Limited
Date: 07-02-2021
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/AN17447
Abstract: Livestock produce 10% of the total CO2-equivalent greenhouse gases in Australia, predominantly as methane from rumen fermentation. Genetic selection has the potential to reduce emissions and be adopted in Australian grazing systems. Developing a breeding objective for reduced methane emissions requires information about heritability, genetic relationships, when best to measure the trait and knowledge of the annual production of methane. Among- and within-animal variation in methane production, methane yield and associated traits were investigated, so as to determine the optimal time of measurement and the relationship between that measurement and the total production of methane. The present study measured 96 ewes for methane production, liveweight, feed intake, rumen volume and components, and volatile fatty acid (VFA) production and composition. Measurements were recorded at three ages and different physiological states, including growing (12 months), dry and pregnant (21 months) and dry (non-pregnant, non-lactating 28 months of age). The single biggest determinant of methane production was feed intake, but there were additional effects of age, proportion of propionate to (acetate+butyrate) in rumen VFA, total VFA concentration and CO2 flux. Rumen volume and pregnancy status also significantly affected methane production. Methane production, CO2 flux, liveweight, feed intake and rumen volume had high repeatability (& %), but repeatability of methane yield and VFA traits were low (& %). There were no interactions between sire and age (or pregnancy status) for methane traits. This suggests that methane could be measured at any time in the production cycle. However, because MY is reduced during pregnancy, it might be best to measure methane traits in dry ewes (neither pregnant nor lactating).
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/AN10096
Abstract: Estimated breeding values for the selection of more profitable sheep for the sheep meat and wool industries are currently based on pedigree and phenotypic records. With the advent of a medium-density DNA marker array, which genotypes ~50 000 ovine single nucleotide polymorphisms, a third source of information has become available. The aim of this paper was to determine whether this genomic information can be used to predict estimated breeding values for wool and meat traits. The effects of all single nucleotide polymorphism markers in a multi-breed sheep reference population of 7180 in iduals with phenotypic records were estimated to derive prediction equations for genomic estimated breeding values (GEBV) for greasy fleece weight, fibre diameter, staple strength, breech wrinkle score, weight at ultrasound scanning, scanned eye muscle depth and scanned fat depth. Five hundred and forty industry sires with very accurate Australian sheep breeding values were used as a validation population and the accuracies of GEBV were assessed according to correlations between GEBV and Australian sheep breeding values . The accuracies of GEBV ranged from 0.15 to 0.79 for wool traits in Merino sheep and from –0.07 to 0.57 for meat traits in all breeds studied. Merino industry sires tended to have more accurate GEBV than terminal and maternal breeds because the reference population consisted mainly of Merino haplotypes. The lower accuracy for terminal and maternal breeds suggests that the density of genetic markers used was not high enough for accurate across-breed prediction of marker effects. Our results indicate that an increase in the size of the reference population will increase the accuracy of GEBV.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/AN13245
Abstract: The aims of this study were to quantify the relationship between age of first oestrus and yearling reproductive performance in maternal-cross ewes in the Information Nucleus Flock data and to estimate genetic and phenotypic correlations between early and later reproductive performance defined as three ages, yearling, hogget and adult in both Merino and maternal-cross ewes. Information on 2218 yearling records, 2047 hogget records and 910 age of first oestrus records were used in the analysis of maternal-cross ewes, whereas 3286 hogget and 2518 adult reproductive records were used in analysis of Merino ewes. Heritability estimates for yearling reproductive performance in maternal-cross ewes ranged from 0.08 ± 0.09 for ewe fecundity to 0.16 ± 0.05 for number of lambs born and were generally higher than hogget heritability estimates for both maternal-cross and Merino ewes. Age at first oestrus was found to have a low heritability, 0.02 with standard errors of 0.07 and 0.06 with and without weight fitted as a covariate. Genetic correlations between age at first oestrus with and without weight fitted as a covariate and yearling reproductive performance were positive, ranging from 0.07 ± 0.49 with lamb survival to 0.94 ± 0.39 with number of lambs born, which was unexpected. Correlations between traits from the same age class were high in both breed groups. Genetic correlations between yearling and hogget performance in maternal-cross ewes were generally lower than one, ranging from 0.46 ± 0.68 for lamb survival and 0.79 ± 0.50 for fertility suggesting that yearling and later reproductive performance are related but genetically different traits. In Merino ewes, the genetic correlations between hogget and adult performance followed a similar pattern. The small number of records in this study generated high standard errors for estimates, which restricts the conclusions that can be drawn. Overall, this study supports current practice used by ‘Sheep Genetics’, the Australian genetic evaluation system for sheep, in considering yearling reproductive performance as a trait separate from later parities for genetic evaluation purposes.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/AN15321
Abstract: Genomic selection could be useful in sheep-breeding programs, especially if rams and ewes are first mated at an earlier age than is the current industry practice. However, young-ewe (1 year old) fertility rates are known to be lower and more variable than those of mature ewes. The aim of the present study was to evaluate how young-ewe fertility rate affects risk and expected genetic gain in Australian sheep-breeding programs that use genomic information and select ewes and rams at different ages. The study used stochastic simulation to model different flock age structures and young-ewe fertility levels with and without genomic information for Merino and maternal sheep-breeding programs. The results from 10 years of selection were used to compare breeding programs on the basis of the mean and variation in genetic gain. Ram and ewe age, availability of genomic information on males and young-ewe fertility level all significantly (P & 0.05) affected expected genetic gain. Higher young-ewe fertility rates significantly increased expected genetic gain. Low fertility rate of young ewes (10%) resulted in net genetic gain similar to not selecting ewes until they were 19 months old and did not increase breeding-program risk, as the likelihood of genetic gain being lower than the range of possible solutions from a breeding program with late selection of both sexes was zero. Genomic information was of significantly (P & 0.05) more value for 1-year-old rams than for 2-year-old rams. Unless genomic information was available, early mating of rams offered no greater gain in Merino breeding programs and increased breeding-program risk. It is concluded that genomic information decreases the risk associated with selecting replacements at 7 months of age. Genetic progress is unlikely to be adversely affected if fertility levels above 10% can be achieved. Whether the joining of young ewes is a viable management decision for a breeder will depend on the fertility level that can be achieved in their young ewes and on other costs associated with the early mating of ewes.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN15738
Abstract: The present study estimated phenotypic and genetic relationships between wool production, reproduction and bodyweight traits in Australian fine-wool Merino sheep. The data for the study originated from the CSIRO Fine Wool Project, Armidale, Australia. Data on wool characteristics, measured at ~10 and 22 months of age, bodyweight and several reproduction traits across consecutive lambing opportunities were analysed. The genetic correlations were moderately negative between fibre diameter measured as yearling and adult, and lamb survival (rg = –0.34 ± 0.15 and rg = –0.28 ± 0.14 respectively) and total number of lambs weaned (rg = –0.32 ± 0.21 and rg = –0.40 ± 0.21 respectively). The genetic correlations of yearling and adult greasy and clean fleece weights with number of lambs weaned and fecundity showed moderately to highly negative relationships and a moderately negative correlation with the number of fetuses at pregnancy scanning. Phenotypic correlations between reproduction and wool production traits were estimated to be zero, with the exception of bodyweight showing low to moderate positive phenotypic correlations with total number of lambs born and weaned. Genetic variances were generally low for the reproduction traits and resulted in low heritability estimates (from h2 = 0.03 ± 0.01 to h2 = 0.12 ± 0.13), with the exception of total number of lambs born (h2 = 0.25 ± 0.03). The study indicated that parameter estimation and trait definition of lifetime reproduction records require careful consideration and more work in this area is required.
Publisher: Oxford University Press (OUP)
Date: 10-2016
Abstract: Feed intake (FI), live weight (LW), and ADG were recorded over 31 d in ninety-six 12-month-old ewes (progeny of 4 sires) given ad libitum access to chaffed lucerne/cereal hay. Methane (CH) and CO emissions of each ewe were measured for 40 to 60 min in portable accumulation chambers (PAC) and in respiration chambers (RC) over 22 h. Testing in RC increased the variability of FI on the test day and depressed the amount eaten from an average of 1,384 to 1,062 g/d FI depression increased by 0.63 ± 0.24 percentage points for every kilogram of additional LW. Repeatabilities of PAC measurements were 0.76 (CH) and 0.81 (CO). After adjusting for LW and ADG, repeatabilities were 0.47 (PAC CH) and 0.43 (PAC CO). Daily FI measurements had similar repeatability (0.76 before and 0.42 after adjustment for LW and ADG). The PAC measurements were highly correlated with mean 31-d FI ( = 0.81 for both CH and CO). After adjustment for LW and ADG, PAC measurements were moderately correlated with residual feed intake (RFI = 0.37 for CH, 0.31 for CO). The CH:CO ratio was also significantly correlated with mean 31-d FI ( = 0.52). After most of the ewes had given birth and raised lambs, repeat PAC measurements were available for 91 of the ewes at 2 years of age (with ad libitum access to the same feed). Correlations with the 2012 PAC measurements were 0.64 (CH) and 0.75 (CO). After adjusting 2014 PAC measurements for LW, correlations with RFI in 2012 were 0.34 (CH) and 0.33 (CO), with a clear relationship between sire means for RFI in 2012 and PAC CH adjusted for LW in 2014. These results suggest that PAC tests under similar feeding conditions are repeatable over an extended time period and can provide useful information on FI and feed efficiency as well as methane emissions. Analyses of RC measurements might need to consider FI depression.
Publisher: National Shellfisheries Association
Date: 04-2013
DOI: 10.2983/035.032.0121
Publisher: Wiley
Date: 10-03-2019
DOI: 10.1111/ADD.14583
Publisher: CSIRO Publishing
Date: 10-03-2022
DOI: 10.1071/AN21270
Abstract: Context Genotype by environment interaction or sire re-ranking between measurements of methane emission in different environments or from using different measurement protocols can affect the efficiency of selection strategies to abate methane emission. Aim This study tested the hypothesis that measurements of methane emission from grazing sheep under field conditions, where the feed intake is unknown, are genetically correlated to measurements in a controlled environment where feed intake is known. Methods Data on emission of methane and carbon dioxide and uptake of oxygen were measured using portable accumulation chambers from 499 animals in a controlled environment in New South Wales and 1382 animals in a grazing environment in Western Australia were analysed. Genetic linkage between both environments was provided by 140 sires with progeny in both environments. Multi-variate animal models were used to estimate genetic parameters for the three gas traits corrected for liveweight. Genetic groups were fitted in the models to account for breed differences. Genetic correlations between the field and controlled environments for the three traits were estimated using bivariate models. Key results Animals in the controlled environment had higher methane emission compared to the animals in the field environment (37.0 ± s.d 9.3 and 35.3 ± s.d 9.4 for two protocols vs 12.9 ± s.d 5.1 and 14.6 ± s.d 4.8 mL/min for lambs and ewes (±s.d) P 0.05) but carbon dioxide emission and oxygen uptake did not significantly differ. The heritability estimates for methane emission, carbon dioxide emission and oxygen uptake were 0.15, 0.06 and 0.11 for the controlled environment and 0.17, 0.27 and 0.35 for the field environment. The repeatability for the traits in the controlled environment ranged from 0.51 to 0.59 and from 0.24 to 0.38 in the field environment. Genetic correlations were high (0.85–0.99) but with high standard errors. Conclusion Methane emission phenotypes measured using portable accumulation chambers in grazing sheep can be used in genetic evaluation to estimate breeding values for genetic improvement of emission related traits. The combined measurement protocol-environment did not lead to re-ranking of sires. Implication These results suggest that both phenotypes could be used in selection for reduced methane emission in grazing sheep. However, this needs to be consolidated using a larger number of animals and sires with larger progeny groups in different environments.
Publisher: Elsevier BV
Date: 04-2008
Publisher: American Psychological Association (APA)
Date: 09-2017
DOI: 10.1037/XAP0000130
Abstract: Unfamiliar, one-to-one face matching has been shown to be error-prone. However, it is unknown whether there is a strong relationship between confidence and accuracy in this task. If there is, then confidence could be used as an indicator of accuracy in real-world face matching settings such as border security, where the objectively correct decision is typically unknown. Two experiments examined the overall confidence-accuracy relationship, as well as the relationship for positive (match) and negative (mismatch) decisions. Furthermore, they tested whether these relationships were affected by factors relevant to applied face matching settings: the proportion of mismatching trials (PMT), and the task orientation of the decision-maker (look for matches, or look for mismatches). Both calibration analyses and signal detection methods were applied to assess performance. The results showed that confidence can have a high correspondence with accuracy overall, regardless of task orientation but with small effects of PMT. Thus, confidence is promising as an indicator of accuracy in face matching. However, PMT systematically produces large detrimental effects on the confidence-accuracy relationships for positive and negative decisions, when considered separately. Signal detection measures help with understanding these effects and proposing future research directions for improving the relationships. (PsycINFO Database Record
Publisher: CSIRO Publishing
Date: 17-08-2021
DOI: 10.1071/AN21054
Abstract: Context Immune competence is a proxy trait for general disease resistance and is based on combined measures of an animal’s ability to mount both a cell-mediated immune response (Cell-IR) and an antibody-mediated immune response (Ab-IR). On the basis of previously described arithmetic, we combined these measures into a single proxy trait for immune competence, named ImmuneDEX (IDEX). Aims Using a population of 3715 Australian Angus steers (n = 2395) and heifers (n = 1320) with genotypes for 45 364 single-nucleotide polymorphisms, we provide the latest genomic estimates of heritability and genetic correlations for IDEX and the components Cell-IR and Ab-IR immune competence phenotypes. Accuracy and bias of genomic predictions of breeding values are also presented and discussed. Methods Measures of Cell-IR, Ab-IR and IDEX were analysed jointly in a tri-variate genomic restricted maximum-likelihood model that contained the fixed effects of contemporary group with 80 levels, the linear covariates of age at measurement and change in skin thickness at control site, and the random polygenic (genomic estimated breeding value, GEBV) and residual effects. Following Method LR procedures, we estimate accuracy, bias and dispersion of genomic predictions using a cross-validation scheme based on five year-of-birth cohorts. Key results We report genomic restricted maximum-likelihood model estimates of heritability of 0.247 ± 0.040 for Cell-IR, 0.326 ± 0.059 for Ab-IR, 0.275 ± 0.046 for IDEX. While a small positive genetic correlation (rg) was estimated between Cell-IR and Ab-IR (rg = 0.138 ± 0.095), strongly positive estimates were obtained between IDEX and Cell-IR (rg = 0.740 ± 0.044) and between IDEX and Ab-IR (rg = 0.741 ± 0.036). Averaged across the five validation sets, the accuracy of GEBV for Cell-IR, Ab-IR and IDEX was 0.405, 0.443 and 0.411 respectively. Also, some significant bias or dispersion can be expected depending on the cohort used as the validation population. Conclusions Consistent with previous findings, immune competence phenotypes are moderately heritable and accurate GEBV can be generated to allow the selection of cattle with an improved ability to mount a general immune response. Implications Our analyses suggest that ImmuneDEX will provide a tool to underpin long-term genetic strategies aimed at improving the immune competence of Australian Angus cattle in production systems, which, in turn, is expected to reduce the incidence of disease and our reliance on antibiotics to treat disease.
Publisher: CSIRO Publishing
Date: 02-08-2021
DOI: 10.1071/AN21099
Abstract: Context A unique population of Merino sheep recorded for a range of production and reproduction traits presented an opportunity to calculate sire variation in dentition which may indicate maturity and influence marketing and selection decisions. A change in the definition of ‘lamb’ in the Australian sheep industry warranted an investigation of the relationship between production, reproduction and dentition. Aims To assess the variation in timing of dentition changes in Merino sheep and determine whether there are associations with key production and reproduction traits. Methods A population of 2150 pedigree-recorded Merino sheep were studied to analyse the sire variation in progeny for a range of dentition changes and production and reproduction traits. Dentition phenotypes included the age animals started to lose the deciduous lamb teeth, the age when one permanent incisor was in wear and the amount of time between these two events. Production records included bodyweight, fat and muscle traits. Reproduction records from the female progeny included the outcome of pregnancy scanning after the first joining opportunity. Sire variation for the age dentition changed was analysed. The effect of progeny age at hogget categorisation on production and reproduction was analysed. Key results Progeny that were heavier, fatter and with higher muscle measurements matured earlier. Female progeny were more likely to be pregnant if classed as hoggets earlier in life. Conclusions Dentition records provided useful indicators of maturity in Merino sheep in this study and can be used to inform decisions regarding the timing of marketing options and the likelihood of success when assessing female progeny for suitability to join at ~18 months of age. Implications Merino sires can exhibit a wide range of variation with respect to the age at which their progeny will mature, as indicated by their dentition. If animals are heavier at an earlier age, they are more likely to mature earlier, which has to be considered when planning nutritional requirements for growing out young male progeny, and females could be more successful as young breeders. Dentition is a useful tool to indicate maturity in young Merino sheep.
Publisher: Elsevier BV
Date: 02-2022
Publisher: CSIRO Publishing
Date: 16-07-2021
DOI: 10.1071/AN21123
Abstract: Context Genomic profiles are the only information source that can uniquely identify an in idual but have not yet been strongly considered in the context of paddock to plate traceability due to the lack of value proposition. Aim The aim of this study was to define the minimum number of single nucleotide polymorphisms (SNP) required to distinguish a unique genotype profile for each in idual s le within a large given population. At the same time, ad hoc approaches were explored to reduce SNP density, and therefore, the size of the dataset to improve computing efficiency and storage requirements while maintaining informativeness to distinguish in iduals. Methods Data for this study included two datasets. One included 78 411 high-density SNP genotypes from commercial Angus cattle and the other 2107 from a research data (1000-bull genome data). In a stepwise approach, different-size SNP panels were explored, with the last step being a successive removal resulting in the smallest set of SNPs that still produced the maximum number of unique genotypes. Key results First study that has demonstrated for large datasets, that ultra-small SNP panels with 20–23 SNPs can generate unique genotypes for up to ~80 000 in iduals, allowing for 100% matching accuracy. Conclusions Ultra-small SNP panels could provide an efficient method to approach the large-scale task of the traceability of beef products through the beef supply chain. Implications Genomic tools could enhance supply-chain traceability.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Sonja Dominik.