EVALUATION OF BEEF SIRES FOR MATERNAL GENETIC EFFECTS ON WEANING WEIGHT AND MEASUREMENT OF GENETIC TRENDS

1983 ◽  
Vol 63 (2) ◽  
pp. 279-283 ◽  
Author(s):  
G. H. CROW ◽  
W. E. HOWELL
Keyword(s):  
Variance Components ◽  
Mixed Model ◽  
Error Variance ◽  
Genetic Effects ◽  
Genetic Trend ◽  
Linear Unbiased Prediction ◽  
Weaning Weight ◽  
Best Linear Unbiased ◽  
Maternal Grandsire ◽  
Genetic Trends

Procedures for evaluating beef sires for maternal genetic effects for weaning weight were developed and used in the calculation of genetic trends. Using the maternal grandsire (MGS) and error variance components, predicted differences (PDs) of MGSs for parity one daughter performance were calculated using Record of Performance data from the Angus, Charolais and Hereford breeds. Best linear unbiased prediction (BLUP) methods were used with a mixed model which included herd-year and MGS effects. The average number of daughter records per MGS was 5.44, 5.26 and 5.12 for Angus, Hereford and Charolais, respectively. As a result of these small numbers of daughter records, the PDs of most MGSs had very large standard errors of prediction. Weighted averages of MGS PDs for each breed in each of the 5 years from 1975 to 1979 were calculated to determine if there was any genetic trend in MGS PDs. There were small trends evident but not sufficient to indicate that any selection pressure was being exerted on maternal ability. Key words: Beef sire evaluation, maternal effects, genetic trends

GENETIC PARAMETERS OF THE MATERNAL GRANDSIRE CONTRIBUTION TO BEEF CATTLE WEANING WEIGHTS

1982 ◽  
Vol 62 (4) ◽  
pp. 1057-1062
Author(s):  
G. H. CROW ◽  
W. E. HOWELL
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Variance Components ◽  
Genetic Parameters ◽  
Mixed Model ◽  
Genetic Effects ◽  
Performance Data ◽  
Maternal Influence ◽  
Weaning Weight ◽  
Maternal Grandsire

Genetic aspects of maternal influence on weaning weights in beef cattle were examined using analyses within breed and parity of dam (first, second, third and fourth and greater parities) of Angus, Charolais and Hereford Record of Performance data. A mixed model which included herd-year and maternal grandsire (MGS) was used. The data were adjusted for calf sex within breed and parity of dam prior to analysis. The heritability of dam influence on her offspring weaning weight averaged 0.23 for first parity data of the three breeds. Heritability for second and third parities of the three breeds were lower than this but averaged 0.16 in parity four and greater. MGSs contributed significantly to variation in weaning weights. Their contribution, however, is a composite of both direct and maternal genetic effects. Key words: Beef cattle, weaning weight, maternal, variance components, heritability

scholarly journals Genetic evaluation and selection correlated response of growth traits in Japanese quail

2020 ◽  
Vol 50 (2) ◽  
pp. 325-333
Author(s):  
M.M. El-Attrouny ◽  
E.A. Manaa ◽  
S.I. Ramadan
Keyword(s):  
Growth Traits ◽  
Best Linear Unbiased Prediction ◽  
Correlated Response ◽  
Genetic Trend ◽  
Linear Unbiased Prediction ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Best Linear Unbiased ◽  
Selection For ◽  
Genetic Trends

Objectives of the current study were to i) investigate effects of selection for bodyweight at four weeks old on bodyweight (BW) and bodyweight gain (BWG) across four generations; ii) estimate correlated response to selection for BW and BWG at different ages; and iii) document best linear unbiased prediction (BLUP) of genetic trends for BW and BWG across four generations of selection. A total of 3540 chicks from 444 sires and 885 dams were used to estimate heritabilities, and genetic and phenotypic correlations for growth traits, including BW at 0, 2, 4, and 6 weeks, and BWG between 0 and 2, 2 and 4, 4 and 6, and 0 and 6 weeks. The selection effects, correlated responses and genetic trend for BW and BWG across generations were quantified by applying the animal model. Estimates of heritability for BW and BWG ranged from 0.22 to 0.42 and from 0.18 to 0.23, respectively. Ranges of genetic and phenotypic correlations for BW varied from 0.31 to 0.92 and 0.05 to 0.65, respectively. Moreover, estimates of genetic and phenotypic correlations for BWG at different ages were from 0.12 to 0.72 and 0.17 to 0.60, respectively. Bodyweight and BWG estimates after four generations of selection were significantly higher than those of the base generation. Moreover, contrasts of generation means were significant across the four generations. The genetic trends across the generations clarified that BLUP estimates for BW and BWG gradually increased with the advance of generations until the fourth generation. Keywords: best linear unbiased prediction, bodyweight, heritability, selection, genetic trend

EVALUATION OF BEEF SIRES ACROSS BREEDS FOR CALVING EASE

1977 ◽  
Vol 57 (4) ◽  
pp. 635-645 ◽  
Author(s):  
L. R. SCHAEFFER ◽  
J. W. WILTON
Keyword(s):  
Maximum Likelihood ◽  
Scoring System ◽  
Variance Components ◽  
Error Variance ◽  
Best Linear Unbiased Prediction ◽  
Linear Unbiased Prediction ◽  
Calving Ease ◽  
Best Linear Unbiased ◽  
Maximum Likelihood Prediction ◽  
Unbiased Prediction

Agriculture Canada and Alberta Record of Performance calving ease records on 54,139 calves from 3,338 sires of 18 breeds were used to evaluate sires by comparisons across breeds of sire. An objective scoring system was applied to the calving ease codes to derive appropriate weights for each category rather than using percentage of unassisted births or assuming equal intervals between categories. Common sire and error variance components were assumed for all breeds of sire. Heritability of calving ease under the model used was estimated to be.10 by maximum likelihood. Prediction of sire values for calving ease scores of future calves were calculated by best linear unbiased prediction procedures. Shorthorn, Hereford, and Angus sires caused relatively few calving difficulties, while Maine-Anjou sires caused more difficulties. Age of dam and sex of calf differences were also important. The range of sire evaluations for calving ease was narrow, but the bulls in either extreme could be identified.

Selection on lean growth in a nucleus of Landrace pigs: an analysis using Gibbs sampling

1996 ◽  
Vol 63 (2) ◽  
pp. 243-253 ◽  
Author(s):  
M. C. Rodriguez ◽  
M. Toro ◽  
L. Silió
Keyword(s):  
Gibbs Sampling ◽  
Variance Components ◽  
Fixed Effects ◽  
Prediction Method ◽  
Environmental Parameters ◽  
Linear Unbiased Prediction ◽  
Normal Distributions ◽  
Lean Growth ◽  
Best Linear Unbiased ◽  
Selection For

AbstractData from 4150 Landrace pigs tested during the period 1989-94 for backfat thickness and age at 100 kg in an open selection nucleus were analysed with the standard restricted maximum likelihood/best linear unbiased prediction method and with a Bayesian approach based on the marginal posterior distributions of parameters of interest achieved via Gibbs sampling. Breeding values and fixed effects were sampled from normal distributions and (co)variance components from inverted Wishart distributions. The Bayesian analysis indicated that the selection was effective for both traits. Assuming flat priors for the (co)variance components, the posterior means of the annual rates of response to selection for both traits were −0·473 days and −0·212 mm. The influence of informative priors constructed from (co)variances estimated in the French Landrace breed on inferences about genetic and common environmental parameters, genetic group effects and total and annual responses was also examined.

scholarly journals Genome-wide Hierarchical Mixed Model Association Analysis

2021 ◽  
Author(s):  
Runqing Yang ◽  
Di Liu ◽  
Zhiyu Hao ◽  
Yuxin Song ◽  
Runqing Yang ◽  
...  
Keyword(s):  
Association Analysis ◽  
Statistical Power ◽  
Mixed Model ◽  
False Negative ◽  
Best Linear Unbiased Prediction ◽  
Least Square ◽  
Linear Unbiased Prediction ◽  
Genomic Breeding ◽  
Genome Wide ◽  
Best Linear Unbiased

Abstract We partitioned the genomic mixed model into two hierarchies to firstly estimate genomic breeding values (GBVs) using the genomic best linear unbiased prediction and then statistically infer the association of GBVs with each SNP using the generalized least square. The genome-wide hierarchical mixed model association study (named Hi-LMM) can correct effectively confounders with polygenic effects as residuals in association tests, preventing potential false negative errors produced with GRAMMAR or EMMAX. The Hi-LMM performs the same statistical power as the exact FaST-LMM with the same computing efficiency as EMMAX. When the GBVs have been estimated precisely, Hi-LMM outperforms existing methods in statistical power, especially through joint association analysis.

Genetic changes generated within the Katanning Merino Resource flocks

2006 ◽  
Vol 46 (7) ◽  
pp. 803 ◽  
Author(s):  
J. C. Greeff ◽  
G. Cox
Keyword(s):  
Body Weight ◽  
Phase 1 ◽  
Fibre Diameter ◽  
Linear Unbiased Prediction ◽  
Genetic Changes ◽  
Breeding Values ◽  
Best Linear Unbiased ◽  
Fleece Weight ◽  
Estimated Breeding Values ◽  
Genetic Trends

Genetic changes for clean fleece weight, fibre diameter and hogget body weight were determined in the Katanning Merino Resource flocks from 1982 to 2004. From 1982 to 1992 genetic trends are presented for individual studs that used mainly subjective classing selection methods (Phase 1) and the genetic trends from 1997 to 2004 demonstrate the genetic changes that can be achieved from using estimated breeding values calculated from best linear unbiased prediction (BLUP) mixed methodology (Phase 2). The results during the first phase show that very few genetic changes occurred in most studs, except for the 4 studs of the Performance Sheep Breeding strain which showed genetic increases in hogget body weight. The genetic trends show that some studs generated change towards their breeding objective, while others show no changes or changes in the opposite direction. In contrast, the use of BLUP estimated breeding values resulted in positive changes in clean fleece weight, fibre diameter and body weight in accordance with the defined breeding objectives.

PSI-17 Genetic analysis of weaning weight in Hungarian Simmental cattle

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 274-275
Author(s):  
Afees Ajasa ◽  
Barnabás Vágó ◽  
Imre Füller ◽  
István Komlósi ◽  
János Posta
Keyword(s):  
Variance Components ◽  
Random Effect ◽  
Random Effect Model ◽  
Genetic Effect ◽  
Genetic Effects ◽  
Covariance Model ◽  
Genetic Covariance ◽  
Weaning Weight ◽  
Effect Model ◽  
Maternal Heritability

Abstract The aim of the study was to partition the total phenotypic variation in the weaning weight of Hungarian Simmental calves into their various causal components. The data used was provided by the Association of Hungarian Simmental Breeders. The dataset comprised of the weaning weight records of 44,278 calves (sire = 879, dam = 14,811) born from 1975 to 2020. A total of six models were fitted to the weaning weight data. Herd, birth year, calving order and sex were included as fixed effects in the models. Model 1 had direct genetic effect as the only random effect. Model 2 had a permanent maternal environment as an additional random effect. Model 3 had both direct and maternal genetic effects, with their covariance is being zero. Model 4 was similar to Model 3 but with non-zero direct-maternal genetic covariance. Model 5 had direct, maternal genetic and permanent environmental effects and a zero direct-maternal genetic covariance. Model 6 was similar to model 5 but the direct-maternal genetic effect was assumed to be correlated. Variance components and genetic parameters were estimated using restricted maximum likelihood method with the Wombat software. The best fit model was determined using the Log likelihood ratio test. Inclusion of direct maternal genetic covariance increased the variance components estimates dramatically which resulted in a corresponding increase in the direct and maternal heritability estimates. The best fitted model (Model 4) had direct and maternal genetic effects as the only random effects with a non-zero direct-maternal genetic covariance. The direct heritability, maternal heritability and direct-maternal genetic correlation estimate of the best model was 0.57, 0.16 and -0.78, respectively. Our result suggests the problem of (co)sampling variation in the partitioning of additive genetic effect into direct and maternal components.

DAIRY HERD GENETIC DIFFERENCES FOR LACTATION PRODUCTION

1982 ◽  
Vol 62 (2) ◽  
pp. 323-331 ◽  
Author(s):  
L. R. SCHAEFFER ◽  
A. KERR ◽  
E. B. BURNSIDE
Keyword(s):  
Milk Yield ◽  
Dairy Herd ◽  
Herd Size ◽  
Best Linear Unbiased Prediction ◽  
Genetic Differences ◽  
Phenotypic Variance ◽  
Linear Unbiased Prediction ◽  
Production Program ◽  
Best Linear Unbiased ◽  
Genetic Trends

Cow estimated transmitting abilities (ETA) for milk yield and fat percent derived by best linear unbiased prediction methods were used to compute averages for each herd and year of calving subclass for herds enrolled on the Record of Production program (ROP). Means and variances of herd averages were tabulated according to province, herd size, and year of calving. The genetic trends in herd averages within herd size categories were positive for milk yields and negative for fat percent. The variance of herd averages has increased since 1958 within herd size categories, but has decreased over all herds due to a shift in size of herds since 1958. Herds with fewer than 20 cows represented 31.7% of the ROP herds in Canada in 1977 while in 1958 they represented 72.4%. However, in 1977 the larger herds did not show any genetic advantage over smaller herds. Ontario herds of size 20–9 cows showed greater variability in average ETA for milk and fat percent than herds in other provinces. Correlations among traits on a herd average basis have not changed in the last 10 yr even though herd averages have changed substantially over the same period. Herd genetic differences accounted for only 2.05% of herd phenotypic variance for milk yield and 12.74% for fat percent. Key words: Genetic differences, herds, cow indexing

Genetic changes in Canadian performance-tested pigs for fat depth and growth rate

1996 ◽  
Vol 76 (1) ◽  
pp. 41-48 ◽  
Author(s):  
B. W. Kennedy ◽  
V. M. Quinton ◽  
C. Smith
Keyword(s):  
Growth Rate ◽  
Performance Testing ◽  
Economic Benefits ◽  
Breeding Value ◽  
Improvement Program ◽  
Linear Unbiased Prediction ◽  
Genetic Changes ◽  
Best Linear Unbiased ◽  
The Mean ◽  
Genetic Trends

Data on more than 1.3 million pigs of four breeds in four regions of Canada were used to estimate genetic changes in fat depth and growth rate from 1976 to 1993. Analysis was by a multi (two)-trait best linear unbiased prediction (BLUP) animal model within breed and across regions. The genetic changes were measured as the changes in average estimated breeding value (EBV) over years.The across-breed average total phenotypic changes from 1976 to 1993 were− 3.9 mm in fat depth (26% of the mean) and− 17 d in age at 100 kg (9% of the mean). The multi-trait BLUP estimates of the genetic trends were similar to single-trait BLUP estimates. The mean EBV and the changes were similar for the four regions. The changes were larger in the Landrace and Yorkshire breeds than in the Duroc and Hampshire. The overall genetic trends were − 1.44% of the mean yr−1 in fat depth and − 0.36% of the mean yr−1 in age at 100 kg. The trend for age at 100 kg increased over time as better methods of deriving the EBV were implemented. The current rates of pig improvement in Canada are good and yield large economic benefits. However, they could be improved to recoup the full gains possible through the Canadian Swine Improvement Program. Key words: Canadian pigs, performance testing, genetic trends

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