Comparison of models and impact of missing records on genetic evaluation of calving ease in a simulated beef cattle population

2005 ◽  
Vol 85 (2) ◽  
pp. 145-155 ◽  
Author(s):  
Yachun Wang ◽  
Flávio S Schenkel ◽  
Stephen P Miller ◽  
James W Wilton
Keyword(s):  
Beef Cattle ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Rank Correlation ◽  
Genetic Evaluation ◽  
Residual Effects ◽  
Calving Ease ◽  
Management Group ◽  
Total Proportion ◽  
The Impact

This study compared the application of a bivariate linear-linear (LL) and a linear-threshold (LT) sire-maternal grandsire model for genetic evaluation of calving ease (CE), using birth weight (BW) as a correlated trait, and assessed the impact of missing records on genetic evaluation of CE in a simulated multi-breed beef population that mimicked phenotypic and genetic parameters of beef cattle in Ontario. Models included fixed age-of-dam by sex-of-calf, management group, breed and heterosis effects, and random direct and maternal genetic, maternal permanent environment and residual effects. The LL model was applied to BW and CE Snell scores, and LT model was applied to BW and CE raw scores. CE evaluations were similar between the LL and LT models with no obvious advantage for either model. The two models performed similarly with respect to accuracy and rank correlation of predicted genetic effects and recovered true values of genetic parameters and fixed effects, except for CE maternal heterosis from LL model. The effect of missing records was assessed using the LT model. All dispersion and location parameters were generally well recovered, even when the total proportion of missing records of both traits was up to 41%. Levels of missing CE and BW records that exist in Ontario do not seem to adversely affect genetic evaluation of CE. Key words: Accuracy, Gibbs sampling, heterosis, Snell score

scholarly journals Comparison of models for estimating genetic parameters and predicting breeding values for birth weight and calving ease in Czech Charolais cattle 

2014 ◽  
Vol 59 (No. 7) ◽  
pp. 302-309 ◽  
Author(s):  
L. Vostrý ◽  
Z. Veselá ◽  
A. Svitáková ◽  
H. Vostrá Vydrová
Keyword(s):  
Animal Model ◽  
Birth Weight ◽  
Beef Cattle ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Genetic Effects ◽  
Parameters Estimation ◽  
Calving Ease ◽  
Heritability Estimates

The most appropriate model for genetic parameters estimation for calving ease and birth weight in beef cattle was selected. A total of 27 402 field records were available from the Czech Charolais breed. For estimation of genetic parameters for calving ease and body weight, three bivariate models were tested: a linear-linear animal model (L-LM) with calving ease classified into four categories (1 – easy; 2–4 – most difficult), a linear-linear animal model (SC-LM) in which calving ease scores were transformed into Snell scores (Snell 1964) and expressed as percentage of assisted calving (ranging 0–100%), and a bivariate threshold-linear animal model (T-LM) with calving ease classified into four categories (1 – easy, 2–4 – most difficult). All tested models included fixed effects for contemporary group (herd × year × season), age of dam, sex and breed of a calf. Random effects included direct and maternal genetic effects, maternal permanent environmental effect, and residual error. Direct heritability estimates for calving ease and birth weight were, with the use of L-LM, SC-LM, and T-LM, from 0.096 ± 0.013 to 0.226 ± 0.024 and from 0.210 ± 0.024 to 0.225 ± 0.026, respectively. Maternal heritability estimates for calving ease and birth weight were, with the use of L-LM, SC-LM, and T-LM, from 0.060 ± 0.031 to 0.104 ± 0.125 and from 0.074 ± 0.041 to 0.075 ± 0.040, respectively. Genetic correlations of direct calving ease with direct birth weight ranged from 0.46 ± 0.06 to 0.50 ± 0.06 for all tested models; whereas maternal genetic correlations between these two traits ranged from 0.24 ± 0.17 to 0.25 ± 0.53. Correlations between direct and maternal genetic effects within-trait were negative and substantial for all tested models (ranging from –0.574 ± 0.125 to –0.680 ± 0.141 for calving ease and from –0.553 ± 0.122 to –0.558 ± 0.118 for birth weight, respectively), illustrating the importance of including this parameter in calving ease evaluations. Results indicate that any of the tested models could be used to reliably estimate genetic parameters for calving ease for beef cattle in the Czech Republic. However, because of advantages in computation time and practical considerations, genetic analysis using SC-LM (transformed data) is recommended.

Genetic parameters for lamb birth weight in spring and autumn lambing

1998 ◽  
Vol 67 (2) ◽  
pp. 327-332 ◽  
Author(s):  
S. A. Al-Shorepy ◽  
D. R. Notter
Keyword(s):  
Birth Weight ◽  
Variance Components ◽  
Genetic Parameters ◽  
Genetic Evaluation ◽  
Residual Effects ◽  
Data Sets ◽  
Negative Effects ◽  
Common Environment ◽  
Genetic Origin ◽  
Combined Data

AbstractGenetic parameters for birth weight were estimated for two sets of spring-born and one set of autumn-born lambs of the same breed composition and genetic origin using a model that included random additive, additive maternal, permanent environmental maternal, litter and residual effects. Litter effects were significant for all data sets, indicating that within-year effects of common environment and (or) non-additive genotype were important for birth weight and should be included in genetic evaluation programmes. Estimates of variance components for autumn-born lambs differed significantly from those obtained from spring-born lambs or from the combined data. In contrast, estimates obtained for the two sets of spring-born lambs did not differ from those obtained when data on all spring-born lambs were pooled. The estimate of h2 for birth weight in spring-born lambs was over twice as large as that obtained for autumn-born lambs (0·26 v. 0·22).In contrast, the across-year repeatability of ewe effects was much larger in autumn lambs (0·41 v. 0·26) as was the full-sib littermate correlation (0·73 v. 0·49). Mean birth weights were also 0·4 to 0·6 kg less in autumn lambs. These results suggest that negative effects on birth weight that have been reported for lambs gestated during summer in equatorial and subtropical regions are also manifested (albeit at reduced levels) in less extreme climates (in this case, 37°, 15' N latitude and 654 m elevation) and that maternal variation exists in the ability of the ewe to maintain adequate lamb birth weights in autumn lambing systems.

GENETIC PARAMETERS FOR CALVING EASE IN AYRSHIRES

1990 ◽  
Vol 70 (1) ◽  
pp. 67-71 ◽  
Author(s):  
R. I. CUE
Keyword(s):  
Maximum Likelihood ◽  
Key Words ◽  
Genetic Correlation ◽  
Direct Effect ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Random Effect ◽  
Restricted Maximum Likelihood ◽  
Calving Ease ◽  
Likelihood Model

Estimates of genetic parameters of calving ease were obtained in Ayrshires. A restricted maximum likelihood model was used with the fixed effects of herd, month-season of calving, sex of calf and dam weight, and the random effect of sire (of calf). The heritability of the direct effect in heifers and in adult cows was approximately 2%, with a genetic correlation between the direct effect in heifers and in adult cows of close to 70%. Key words: Variance, heritability, calving ease, Ayrshire

scholarly journals Selection of a suitable data set and model for the estimation of genetic parameters of the weaning weight in beef cattle

2007 ◽  
Vol 50 (6) ◽  
pp. 562-574
Author(s):  
L. Vostrý ◽  
J. Přibyl ◽  
Z. Veselá ◽  
V. Jakubec
Keyword(s):  
Beef Cattle ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Genetic Effect ◽  
Suitable Model ◽  
Data Set ◽  
Weaning Weight ◽  
Estimation Of Genetic Parameters ◽  
Selection Of

Abstract. The objective of this paper was to select a suitable data subset and statistical model for the estimation of genetic parameters for weaning weight of beef cattle in the Czech Republic. Nine subsets were tested for the selection of a suitable subset. The subsets differed from each other in the limit of sampling criteria. The most suitable subset satisfied these conditions: at least 5 individuals per each sire, 5 individuals per HYS (herd, year, season), 2 sires per HYS, and individuals per dams that have at least one half-sister and two offspring (n = 4 806). The selection of a suitable model was carried out from 10 models. These models comprised some of the random effects: direct genetic effect, maternal genetic effect, permanent maternal environment effect, HYS, sire × herd or sire × year interaction, and some of the fixed effects: dam’s age, sex (young bull, heifer × single, twin born), HYS, year, herd. The direct heritability (h2a) ranged from 0.06 to 0.17, of maternal heritability (h2m) from 0.03 to 0.06. The genetic correlations between the direct and maternal effect (ram) were in the range of –0.15 –0.42.

138 GENETIC PARAMETER ESTIMATION FOR EMBRYO TRANSFER TRAITS

2009 ◽  
Vol 21 (1) ◽  
pp. 169 ◽  
Author(s):  
F. A. Di Croce ◽  
A. M. Saxton ◽  
N. R. Rohrbach ◽  
F. N. Schrick
Keyword(s):  
Embryo Transfer ◽  
Fixed Effects ◽  
Large Scale ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Selection ◽  
Reproductive Traits ◽  
Residual Effects ◽  
Limiting Factors ◽  
Phenotypic Traits

Genetic selection has made tremendous progress on economically important traits in the beef industry. Most of the progress has been from quantitative genetics through use of expected progeny differences (EPD). These values allow prediction of differences in progeny of a sire compared to progeny of other sires. Development of EPD for male and female reproductive traits has largely been ignored because of low heritability of reproductive traits, even though reproduction plays a vital role in the economics of beef operations. Therefore, continued research in the area of genetic selection for fertility is becoming increasingly important. Critical limiting factors for animal breeding programs using MOET nucleus schemes include variability in superovulatory response of donor animals and resulting pregnancy of transferred embryos. Thus, the overall objective of this research was to develop genetic parameters associated with MOET to assist producers in identifying animals with greater genetic merit for these protocols. Records were examined from a large-scale MOET system in beef cattle that contained data only for cows in which at least one transferable embryo was obtained. Data on these animals were extracted and analyzed on 10 425 transferred embryos (2900 collections) from 611 donor animals (Angus, Brangus, and Charolais) utilizing semen from 215 bulls. Phenotypic traits examined included pregnancy status of the recipient following transfer (ET-preg; determined by rectal palpation at 60 days post-transfer and/or confirmed calving date of recipient), number of transferable embryos per collection (ET-trans), and number of unfertilized ova at collection (ET-UFO). Basic statistical analysis and pedigree/trait files were developed using procedures in SAS (SAS Institute, Cary, NC). Genetic parameters were estimated for a single-trait animal model using restricted maximum likelihood (REML) procedures in Wombat (Meyer K 2007 Zhejiang Uni. Science B 8, 815–821). Wombat also computed EPD and standard errors for each trait evaluated. The model included fixed effects of year as well as random animal and residual effects. The EPD for ET-preg ranged from –6.1 to 4.4% (SE = 2.2 to 4.2) for semen sires (sires of the transferred embryos) and –5.3 to 3.8% (SE = 3.2 to 4.2) for donor animals. Additionally, the heritability estimated for ET-preg was 0.03. Heritability estimated for ET-trans was 0.00, indicating minute genetic variation and thus, EPD were not presented. Heritability estimated for ET-UFO was 0.05 with EPD values (deviation of the number of UFO from the mean) ranging from –0.6 to 0.8 (SE = 0.3 to 0.6) for semen sires and –0.4 to 1.1 (SE = 0.5 to 0.6) for donor cows. As previously shown for reproductive traits, heritability of ET-preg, ET-trans, and ET-UFO was low. Genetic improvement in fertility by selection on embryo transfer traits is possible, but progress would be slow. Further studies are underway on a larger dataset to refine these estimates and to examine repeatability.

GENETIC PARAMETERS FOR MATERNAL TRAITS IN BEEF CATTLE

1988 ◽  
Vol 68 (1) ◽  
pp. 119-128 ◽  
Author(s):  
D. TRUS ◽  
J. W. WILTON
Keyword(s):  
Beef Cattle ◽  
Fixed Effects ◽  
Genetic Correlations ◽  
Monitoring Program ◽  
Parameter Estimates ◽  
Genetic Trend ◽  
Calving Ease ◽  
Modified Method ◽  
Maternal Heritability ◽  
Maternal Grandsire

Direct (D) and maternal (M) parameters for birth weight (BW), preweaning gain (WG) and calving ease (CE) were estimated for Angus (AN), Hereford (HE), Charolais (CH), Simmental (SM) and Shorthorn (SS). Data for the study were collected by Agriculture Canada from 1973 to 1983 for use in the National Sire Monitoring Program. Variances were estimated for each breed by a modified Method IV applied to a sire-maternal grandsire model with herd-year-seasons and age of dam × sex of calf as fixed effects. Genetic correlations (D/M) between D and M effects for WG in AN, HE, SS, CH and SM were −0.54, −0.42, −0.14, −0.26 and −0.45, respectively. Corresponding estimates of direct heritability for WG were 0.39, 0.30, 0.39, 0.27 and 0.43 and of maternal heritability 0.21, 0.27, 0.26, 0.16 and 0.20. Estimates for BW were similar to those for WG. Estimates of the D/M correlation for CE were −0.43, −0.15, −0.32, −0.74 and −0.27, of the direct heritability 0.28, 0.17, 0.19, 0.33 and 0.21, and of the maternal heritability 0.22, 0.13, 0.19, 0.23 and 0.27 for AN, HE, SS, CH and SM, respectively. Genetic trend and the introduction of new genetic lines are expected to have influenced parameter estimates. Due to negative D/M correlation estimates and moderate maternal heritabilities, selection for both the D and M components of maternal traits is advised. Key words: Variance, direct, maternal, heritability, genetic correlation, beef cattle

scholarly journals Estimates of direct and maternal genetic parameters for weight traits and backfat thickness in a multibreed population of beef cattle

1999 ◽  
Vol 79 (4) ◽  
pp. 433-439 ◽  
Author(s):  
J. J. Tosh ◽  
R. A. Kemp ◽  
D. R. Ward
Keyword(s):  
Beef Cattle ◽  
Maternal Effects ◽  
Variance Components ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Backfat Thickness ◽  
Residual Effects ◽  
Parameter Estimates ◽  
Ratio Test ◽  
Environmental Correlations

Variance components were estimated for weight at birth, weaning, and 365 d of age, and yearling ultrasonic backfat thickness in a multibreed population of beef cattle. Data (n = 5880) were available on F1 animals and various crosses leading up to, and including, a composite breed (7/16 British, 1/4 Charolais, 1/4 Simmental, and 1/16 Limousin). Single- and two-trait analyses were conducted using an animal model and derivative-free REML procedures. Covariates representing fractional contributions of each of the four purebred groups and average heterotic effects, both direct and maternal, accounted for breed composition. Direct and maternal genetic, maternal permanent environmental, and residual effects were the random variables. Only minor differences existed between parameter estimates obtained from the various analyses. Mean direct heritabilities were 0.51, 0.33, 0.48, and 0.37 for weight at birth, weaning, and 365-d, and backfat, respectively, which, though well within the range of published estimates, seemed higher than average, indicating diversity in the founding purebreds. Mean maternal heritabilites were 0.09, 0.13, and 0.08 for the three consecutive weights. A likelihood ratio test showed maternal heritability and(or) the direct-maternal correlation was important (P < 0.001) for 365-d weight. Averaged across weights, the direct-maternal correlation was 0.07, lacking evidence of genetic antagonism. No age of dam or random maternal effects on backfat were apparent. Phenotypic correlations between weight at birth and weaning and weight at weaning and 365-d were 0.46 and 0.76, respectively. Though moderate between birth and weaning weight, maternal genetic and permanent environmental correlations between weaning and 365-d weight approached unity, demonstrating maternal carryover effects. Phenotypic and genetic correlations of 0.19 and –0.13, respectively, implied a limited association between 365-d weight and backfat, which possibly would have been stronger had fat been measured later in life. Estimates of variance components suitable for general use can be obtained from data from multibreed animals by considering breed and heterotic effects. Key words: Beef cattle, crossbreds, genetic parameters, heritability, maternal effects

scholarly journals Genetic analysis of visual scores and their relationships to mature female weight in Nellore breed

2011 ◽  
Vol 40 (1) ◽  
pp. 100-105 ◽  
Author(s):  
Inaê Cristina Regatieri ◽  
Arione Augusti Boligon ◽  
Lucia Galvão de Albuquerque
Keyword(s):  
Fixed Effects ◽  
Genetic Correlations ◽  
Mature Female ◽  
Residual Effects ◽  
Likelihood Method ◽  
Adult Age ◽  
Contemporary Group ◽  
Management Group ◽  
Definition Of ◽  
Female Weight

Data from 79,884 Nellore breed animals were used to estimate genetic parameters and to evaluate the relationships among scores of conformation, precocity and musculature obtained at weaning and after yearling ages and weight of mature females. It was used the restricted maximum likelihood method in a multi-trait analysis with the model that included direct additive genetic and residual effects, as random effects, and the fixed effects of contemporary group and, as covariables, animal age at weighing and age of dam at calving (except for weight of females at adult age). Contemporary groups at weaning were defined by the variables: sex, herd, year and month of birth, and management group at birth and weaning. For definition of contemporary group at yearling, it was also included the variable management group at yearling. For female weight at mature age, contemporary group was composed of herd, year of birth, management group at yearling, weighing year and season. Maternal genetic and maternal permanent environment effects were also included in the model for analyses of scores of conformation, precocity and muscularity at weaning. The direct herdability estimates obtained were the following: 0.18 ± 0.02 for conformation at weaning score, 0.21 ± 0.01 for precocity at weaning score, 0.22 ± 0.01 for muscularity at weaning score, 0.24 ± 0.01 for conformation at yearling score, 0.27 ± 0.01 for precocity at yearling score, and 0.26 ± 0.01 for muscularity score at yearling and 0.42 ± 0.02 for mature female weight. Genetic correlations estimated among visual scores measured at weaning and after yearling were positive, ranging from intermediate to high magnitude (0.56 ± 0.03 to 0.85 ± 0.01). On the other hand, genetic correlations estimated between visual scores and mature female weight were positive and intermediate, ranging from 0.21 ± 0.03 to 0.35 ± 0.03. The results obtained indicate that selection of animals with higher visual scores, mainly at yearling age, may promote an increase on mature female weight.

Scope for genetic evaluation and selection of beef cattle for growth to weaning when birth dates are not recorded

1994 ◽  
Vol 45 (4) ◽  
pp. 819
Author(s):  
K Meyer ◽  
HU Graser
Keyword(s):  
Beef Cattle ◽  
Genetic Correlation ◽  
Western Australia ◽  
Variance Components ◽  
Genetic Parameters ◽  
Selection Criterion ◽  
Genetic Evaluation ◽  
Selection Experiment ◽  
Weaning Weight ◽  
Selection Of

Estimates of (co)variance components and genetic parameters were obtained for a preweaning weight, recorded between 2 and 5 months after birth, and the subsequent gain till weaning for two herds in a selection experiment in Western Australia. Analyses were carried out both accounting for age at weighing and assuming birth dates and thus ages were unknown. On adjusting for the interval between weighings, preweaning gain appeared to be independent of age and equally heritable to weaning weight. Estimates of the direct genetic correlation between preweaning gain and weaning weight (adjusted for age) were 0.9 or higher, while both genetic and permanent environmental maternal correlations were close to unity. Implications for the use of preweaning weight as an alternative selection criterion to weaning weight when birth dates are not recorded are discussed.

scholarly journals Additive and non-additive effects for mature weight in beef cattle

2020 ◽  
Vol 28 (1-2) ◽  
pp. 19-28
Author(s):  
Ana Guillenea ◽  
Mario Lema ◽  
Diego Gimeno ◽  
Olga Ravagnolo ◽  
Ana Carolina Espasandín
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Parameters Estimation ◽  
Repeated Measure ◽  
Breed Group ◽  
Animal Growth ◽  
Mature Weight ◽  
The Impact ◽  
Mature Size ◽  
Zebu Cows

Selection has emphasized animal growth, leading to an increase in their mature size affecting in some cases the pregnancy of the cows and the efficiency of the systems. Usually, crossbreeding improve productivity because of the genetic effects that the cows exploit, but the impact on mature weight (MW) has not been studied. The present study aimed at estimating MW and genetic parameters associated with the MW in crosses between two British breeds: Hereford (H/H) and Angus (A/A), a Continental: Salers (S/S), and a Zebu: Nelore (N/N). MW was analyzed at 4; 4.5; 5; 5.5 and 6 years of age using a repeated-measure sire model. For parameters estimation, an additive – dominant model was used including the fixed effects of breed group, contemporary group, and age as covariate linear and quadratic, with the linear regression fitted by breed group. Permanent environmental and sire were included as random effects. According to the results, it is expected to observe heterosis between H/H and N/N, however, the structure of the data may not be enough for estimate accurately the genetic parameters in this trait. The A/H, N/H, S/H, S/SH and H/NH cows were heavier than the H/H cows. All the breed groups continue gaining weight until six years of age. The results revealed that British crossbred animals are heavier than H/H at the first crossing but not in the following. Crossbred cows with proportions of 0.5 and greater for the Continental breed are heavier than H/H cows. Crosses between British and Zebu cows have higher mature weight than H/H at the first crossing and in backcrosses toward the British in all ages.

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