Genetic parameters for liveweight, wool and worm resistance traits in multi-breed Australian meat sheep. 1. Description of traits, fixed effects, variance components and their ratios

2016 ◽  
Vol 56 (9) ◽  
pp. 1442 ◽  
Author(s):  
D. J. Brown ◽  
A. A. Swan ◽  
J. S. Gill ◽  
A. J. Ball ◽  
R. G. Banks
Keyword(s):  
Genetic Variation ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Eye Muscle ◽  
Internal Parasite ◽  
Internal Parasites ◽  
Genetic Evaluations ◽  
Meat Sheep ◽  
Breed Sheep ◽  
Resistance Traits

Sheep breeders in Australia that focus on lamb production simultaneously breed sheep that have higher growth rate, improved carcass quality and are resistant to internal parasites. The objective of this study was to estimate genetic parameters for 11 traits recorded in Australian meat sheep, covering liveweight, carcass and internal parasite resistance traits. As the population of meat sheep in this database have become increasingly crossbred this study also investigates the genetic variation within and between breeds. The data comprised 1 046 298 animals from 149 Poll Dorset, 17 Suffolk, 24 Texel and 118 White Suffolk flocks. The results are averages of analyses of 10 datasets constructed by randomly sampling 25% of these flocks. There was considerable genetic variation in all traits analysed: the lowest heritabilities (0.12) were found for weaning weight and the highest heritabilities (0.31–0.32) for eye muscle depth. There were also significant differences between breeds for most traits, which breeders appear to be utilising through crossbreeding. Direct heterosis effects were small and only significant for the liveweight traits ranging from 2% to 3.4% of the phenotypic means. Maternal heterosis was not significant for any trait studied. The inclusion of heterosis effects in the model did not significantly influence the estimated genetic parameters. The results from this study have been used to review the genetic parameters used in the LAMBPLAN routine genetic evaluations conducted by Sheep Genetics.

Genetic parameters for liveweight, wool and worm resistance traits in multi-breed Australian meat sheep. 2. Genetic relationships between traits

2016 ◽  
Vol 56 (9) ◽  
pp. 1449 ◽  
Author(s):  
D. J. Brown ◽  
A. A. Swan
Keyword(s):  
Genetic Relationships ◽  
Genetic Correlations ◽  
High Growth ◽  
High Growth Rate ◽  
Eye Muscle ◽  
Internal Parasite ◽  
Internal Parasites ◽  
Negative Effect ◽  
Meat Sheep ◽  
Resistance Traits

Australian sheep breeders aim to simultaneously breed sheep that have high growth rate, superior carcass quality and are resistant to internal parasites. The objective of this study was to estimate genetic and phenotypic relationships between 11 traits recorded in Australian meat sheep, covering liveweight, carcass and internal parasite resistance traits. The data comprised 1 046 298 animals from 149 Poll Dorset, 17 Suffolk, 24 Texel and 118 White Suffolk flocks. Within all trait groups, the different age expressions were moderately to highly correlated. The genetic correlations between liveweight with both fat and eye muscle depth were generally negative ranging between –0.10 and –0.42. Fat and eye muscle depth were moderately correlated (0.27–0.59). Results indicate that selection for an increase in liveweight will have a negative effect on fat and eye muscle depth. The negative correlations of ultrasound scan traits and worm egg count indicates that animals with high genetic merit for fat and eye muscle depth are less prone to infection from internal parasites. The results from this study have been used to review the genetic correlations used in the LAMBPLAN routine genetic evaluations conducted by Sheep Genetics.

Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 1. Description of traits, model comparison, variance components and their ratios

2008 ◽  
Vol 48 (9) ◽  
pp. 1177 ◽  
Author(s):  
A. E. Huisman ◽  
D. J. Brown ◽  
A. J. Ball ◽  
H.-U. Graser
Keyword(s):  
Model Comparison ◽  
Genetic Parameters ◽  
Fibre Diameter ◽  
Genetic Effect ◽  
Parasite Resistance ◽  
Merino Sheep ◽  
Internal Parasite ◽  
Reproduction Traits ◽  
Genetic Evaluations ◽  
Resistance Traits

Both wool and sheep meat industries are interested in sheep that have a high reproduction performance and are resistant to internal parasites, in addition to the traditional traits. There is considerable interest in breeding sheep for wool, carcass, reproductive and internal parasite resistance traits simultaneously. The objective of this study was to estimate single trait genetic parameters for 40 traits recorded in Merino sheep, covering bodyweight, carcass, wool, reproduction and internal parasite resistance traits. This also involved determining the appropriate models. The results from this study will be used to review the genetic parameters used in the routine genetic evaluations conducted by Sheep Genetics. The most appropriate models included a maternal genetic effect and covariance between direct and maternal genetic effects for most of the bodyweight traits, greasy and clean fleece weight, fibre diameter and coefficient of variation of fibre diameter. The permanent environment due to the dam was not included for any trait. There was considerable genetic variation in most traits analysed; lowest heritabilities (0.09–0.10) were found for number of lambs born and weaned per lambing opportunity, and highest heritabilities (0.62–0.77) for fibre diameter. The estimated heritabilities and genetic variances, in combination with the estimated correlations, indicate that there is potential to make genetic improvement in most traits currently recorded in Australian Merino sheep.

Utilization of year-round data in the estimation of genetic parameters for internal parasite resistance traits in Dorper sheep

2017 ◽  
Vol 151 ◽  
pp. 5-10 ◽  
Author(s):  
L. Ngere ◽  
J.M. Burke ◽  
A.D. Herring ◽  
J.O. Sanders ◽  
T.M. Craig ◽  
...  
Keyword(s):  
Genetic Parameters ◽  
Parasite Resistance ◽  
Internal Parasite ◽  
Dorper Sheep ◽  
Estimation Of Genetic Parameters ◽  
Resistance Traits

Genetic parameters of carcass quality in Down cross sheep

1968 ◽  
Vol 10 (2) ◽  
pp. 183-191 ◽  
Author(s):  
J. C. Bowman ◽  
J. E. Marshall ◽  
J. S. Broadbent
Keyword(s):  
Genetic Variation ◽  
Genetic Parameters ◽  
Carcass Traits ◽  
Genetic Correlations ◽  
Carcass Quality ◽  
Correction Factors ◽  
Muscle Area ◽  
Eye Muscle ◽  
Additive Genetic Variation ◽  
Commercial Value

This report gives an account of the paternal half-sib analysis of carcass quality, based on commercial joint dissection, on Down cross sheep collected in the four years 1962–65 inclusive. It also includes a discussion of the multiplicative correction factors used, and the phenotypic and genetic correlations between all the traits, estimated from the pooled within-farm, within-year analysis. It shows that there is very little genetic variation for many of the characters but that the percentage leg, percentage best end, age at slaughter and eye-muscle area have much additive genetic variation remaining for worthwhile response to be expected from selection. These three carcass traits are also the most important characters in determining the commercial value and saleability of lamb. From the results obtained it is argued that there is still much genetic variation for fat development in sheep.

scholarly journals Estimation of genetic parameters for melanoma in the Old Kladruber horse

2012 ◽  
Vol 57 (No. 2) ◽  
pp. 75-82 ◽  
Author(s):  
L. Vostrý ◽  
B. Hofmanová ◽  
H. Vostrá Vydrová ◽  
J. Přibyl ◽  
I. Majzlík
Keyword(s):  
Animal Model ◽  
Genetic Variation ◽  
Correlation Coefficient ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Rank Correlation ◽  
Genetic Effect ◽  
Pedigree Information ◽  
Direct Genetic Effect ◽  
Estimation Of Genetic Parameters

The aim of this study was to assess the prevalence of melanoma to investigate a possible genetic variation of this trait in the Old Kladruber horse. A total of 564 grey varieties of the Old Kladruber horse, 238 males and 326 females, with five generations of ancestors (n = 1245 animals) were analysed. Melanoma status was recorded for different stages. Three different analyses were conducted: a linear animal model (LM) with melanoma classified into five categories, threshold animal model (TM) with melanoma classified into five categories and threshold animal model (TMb) with melanoma classified into two categories (0 = absence, 1 = presence). All models included the fixed effects of year of evaluation, age, line, sex, greying level, random direct genetic effect, and the effect of animal’s permanent environment. Heritability for melanoma occurrence was estimated for LM – 0.09, for TM – 0.27, and for TMb – 0.11. The coefficient of repeatability was estimated for LM – 0.77, for TM – 0.90, and for TMb – 0.99. The values of the Pearson’s correlation coefficient and Spearmen’s rank correlation coefficient among breeding values estimated by LM, TM, and TMb models were from 0.82 to 0.88 and from 0.83 to 0.90, respectively, for data with pedigree information and from 0.77 to 0.84 and 0.77 to 0.88, respectively, for a subset of animals with measurements. Results suggest that additive genetic variation of melanoma occurrence in the Old Kladruber horse seems large enough to be exploited in a specific breeding programme.  

scholarly journals Bayesian inference of genetic parameters for reproductive and performance traits in White Leghorn hens

2018 ◽  
Vol 63 (No. 6) ◽  
pp. 230-236 ◽  
Author(s):  
J.O. Rosa ◽  
G.C. Venturini ◽  
T.C.S. Chud ◽  
B.C. Pires ◽  
M.E. Buzanskas ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Fixed Effects ◽  
Egg Production ◽  
Genetic Parameters ◽  
Laying Hens ◽  
Reproductive Traits ◽  
A Posteriori ◽  
White Leghorn ◽  
Performance Traits ◽  
And Performance

This study estimated the genetic parameters for reproductive and performance traits and determined which ones can be used as selection criteria for egg production in laying hens using the Bayesian inference. The data of 1894 animals from three generations of White Leghorn laying hens were analyzed for fertility (FERT), hatchability (HATC), and birth rate measurements at 60 weeks of age (BIRTH), body weight at 16 and 60 weeks of age (BW16 and BW60), age at sexual maturity (ASM), egg height/width ratio, weight, and density at 28, 36, and 40 weeks of age (RHW28, RHW36, RHW40, WEGG28, WEGG36, WEGG40, DENS28, DENS36, and DENS40, respectively) traits. The genetic parameters were estimated by the Bayesian inference method of multi-trait animal model. The model included the additive and residual genetic random effects and the fixed effects of generation. The a posteriori mean distributions of the heritability estimates for reproductive traits ranged from 0.14 ± 0.003 (HATC) to 0.22 ± 0.005 (FERT) and performance from 0.07 ± 0.001 (RHW28) to 0.42 ± 0.001 (WEGG40). The a posteriori mean distributions of the genetic correlation between reproductive traits ranged from 0.18 ± 0.026 (FERT and HACT) to 0.79 ± 0.007 (FERT and BIRTH) and those related to performance ranged from –0.49 ± 0.001 (WEGG36 and DENS36) to 0.75 ± 0.003 (DENS28 and DENS36). Reproductive and performance traits showed enough additive genetic variability to respond to selection, except for RHW28. This trait alone would have little impact on the genetic gain because environmental factors would have a higher impact compared to those from the additive genetic factors. Based on the results of this study, the selection applied on the BIRTH trait can be indicated to improve FERT and HATC of eggs. Furthermore, the use of the WEGG40 could improve egg quality in this population.

Genetic importance of fat and eye muscle depth in Merino breeding programs

2016 ◽  
Vol 56 (4) ◽  
pp. 690 ◽  
Author(s):  
D. J. Brown ◽  
A. A. Swan
Keyword(s):  
Carcass Traits ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Economic Index ◽  
Parasite Resistance ◽  
Eye Muscle ◽  
Breeding Programs ◽  
Dual Purpose ◽  
Internal Parasite ◽  
Reproduction Traits

Australian Merino breeders have traditionally selected animals for breeding predominately on the basis of wool characteristics. Over recent decades, an increasing proportion of Merino breeders are interested in producing a ewe that can be used for prime-lamb production, but that also performs well for wool characteristics. Correlations between ultrasound carcass traits and other traits such as wool, internal parasite resistance and reproduction traits, are not very well known. The aims of this study were three-fold: (1) to estimate the genetic relationships between ultrasound carcass traits and wool, internal parasite resistance and reproduction traits, (2) to determine the value of recording ultrasound carcass traits in Merino breeding programs, and (3) to evaluate the impact of improving ewe genetic merit for fatness on their reproduction performance. Ultrasound fat and eye muscle depth had small to moderate genetic correlations with most traits, with positive correlations observed for bodyweight, fibre diameter, fibre curvature and reproduction, and negative correlations observed for fleece weight, fibre diameter coefficient of variation, worm egg count and breech wrinkle. As expected on the basis of these genetic correlations, estimated breeding values for fat depth of ewes had a positive association with their observed reproduction performance, but the effect explained only minimal variation in reproductive performance, and was extremely variable among flocks and years. A range of measurement scenarios was investigated for three standard MERINOSELECT indexes. Measuring fat and eye muscle depth resulted in 3%, 4% and 21% additional economic index gain for the fine, medium and dual purpose indexes, respectively, whereas measuring reproduction traits directly resulted in 17%, 27% and 45% additional gain in the economic index. Dual purpose index gains benefited more from measuring ultrasound carcass traits as it is the only index with a direct economic value placed on carcass traits. Measuring fat and eye muscle depth also resulted in a greater reduction in worm egg count. The results indicated that desirable genetic progress can be made in wool, ultrasound carcass, internal parasite resistance and number of lambs born and weaned simultaneously using multiple trait selection to account for the mix of favourable and unfavourable correlations between these traits. These results also demonstrated that the best method to maximise economic gain is to measure as many traits (or closely correlated traits) in the breeding objective as possible.

Genetic Parameters and Genotype-by-Environment Interactions in Regional Progeny Tests of Pinus taeda L. in the Southern USA

2020 ◽  
Author(s):  
Edwin Lauer ◽  
Andrew Sims ◽  
Steven McKeand ◽  
Fikret Isik
Keyword(s):  
Genetic Variation ◽  
Pinus Taeda ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Breeding Program ◽  
Model Fit ◽  
Genotype By Environment Interactions ◽  
Genotype By Environment ◽  
Progeny Tests ◽  
Pinus Taeda L

Abstract Genetic parameters were estimated using a five-series multienvironment trial of Pinus taeda L. in the southern USA. There were 324 half-sib families planted in five test series across 37 locations. A set of six variance/covariance matrices for the genotype-by-environment (G × E) effect for tree height and diameter were compared on the basis of model fit. In single-series analysis, extended factor analytical models provided generally superior model fit to simpler models for both traits; however, in the combined-series analysis, diameter was optimally modeled using simpler variance/covariance structures. A three-way compound term for modeling G × E interactions among and within series yielded substantial improvements in terms of model fit and standard errors of predictions. Heritability of family means ranged between 0.63 and 0.90 for both height and diameter. Average additive genetic correlations among sites were 0.70 and 0.61 for height and diameter, respectively, suggesting the presence of some G × E interaction. Pairs of sites with the lowest additive genetic correlations were located at opposite ends of the latitude range. Latent factor regression revealed a small number of parents with large factor scores that changed ranks significantly between southern and northern environments. Study Implications Multienvironmental progeny tests of loblolly pine (Pinus taeda L.) were established over 10 years in the southern United States to understand the genetic variation for the traits of economic importance. There was substantial genetic variation between open-pollinated families, suggesting that family selection would be efficient in the breeding program. Genotype-by-environment interactions were negligible among sites in the deployment region but became larger between sites at the extremes of the distribution. The data from these trials are invaluable in informing the breeding program about the genetic merit of selection candidates and their potential interaction with the environment. These results can be used to guide deployment decisions in the southern USA, helping landowners match germplasm with geography to achieve optimal financial returns and conservation outcomes.

High genetic variation and moderate to high values for genetic parameters of Picea abies resistance to Pissodes strobi

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
Marie-Josée Mottet ◽  
Josianne DeBlois ◽  
Martin Perron
Keyword(s):  
Genetic Variation ◽  
Picea Abies ◽  
Genetic Parameters ◽  
Pissodes Strobi

PSVI-20 Extent of genetic variation in feeding behavior and genetic associations with performance and feed efficiency in crossbred growing cattle

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 233-234
Author(s):  
David N Kelly ◽  
Roy D Sleator ◽  
Craig P Murphy ◽  
Stephen B Conroy ◽  
Donagh P Berry
Keyword(s):  
Genetic Variation ◽  
Feeding Behavior ◽  
Energy Intake ◽  
Feed Efficiency ◽  
Fixed Effects ◽  
Feeding Rate ◽  
Feeding Time ◽  
Genetic Associations ◽  
Event Duration ◽  
Growing Cattle

Abstract To the best of our knowledge, the genetic variability in feeding behavior, as well as relationships with performance and feed efficiency, has not been investigated in a cattle population of greater than 1,500 animals. Our objective was to quantify the genetic parameters of several feeding behavior traits, and their genetic associations with both performance and feed efficiency traits, in crossbred growing cattle. Feed intake and live-weight data were available on 6,088 bulls, steers and heifers; of these, 4,672 cattle had backfat and muscle ultrasound data, and 1,548 steers and heifers had feeding behavior data. Genetic (co)variance parameters were estimated using animal linear mixed models; fixed effects included test group, heterosis, recombination loss, dam parity, age in months at the end of test, and the two-way interaction between age in months at the end of test and sex. Heritability was estimated to be 0.51 (0.097), 0.61 (0.100), 0.44 (0.093), 0.48 (0.094), and 0.47 (0.095) for feed events per day, feeding time per day, feeding rate, feed event duration, and energy intake per feed event, respectively. Coefficients of genetic variation ranged from 0.11 (feeding time per day) to 0.22 (feed event duration). Genetically heavier cattle with a higher energy intake per day, and faster growth rate, had a faster feeding rate and a greater energy intake per feed event. Genetic correlations between feeding behavior and feed efficiency were generally not different from zero, however, there was a genetic correlation of 0.36 (0.11) between feeding time per day and residual energy intake. Significant heritable and exploitable genetic variation exists in several feeding behavior traits in crossbred growing cattle which are also correlated with several performance traits. As some feeding behavior traits may be relatively less resource intensive to measure, they could be useful as predictor traits in beef cattle genetic evaluations.

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