Covariance components and prediction for additive and nonadditive preweaning growth genetic effects in an Angus-Brahman multibreed herd.
TL;DR: The results showed that it is feasible to evaluate sires for additive and nonadditive genetic effects in a structured multibreed population and data from purebred breeders and commercial producers will be needed to accomplish the same goal at a national level.
Abstract: Estimates of covariances and sire expected progeny differences of additive and nonadditive direct and maternal genetic effects for birth and weaning weights were obtained using records from 1,581 straightbred and crossbred calves from the Angus-Brahman multibreed herd at the University of Florida. Covariances were estimated by Restricted Maximum Likelihood, using a Generalized Expectation-Maximization algorithm applied to multibreed populations. Estimates of heritabilities and additive genetic correlations for straightbred and crossbred groups were within the ranges of values found in the literature for these traits. Maximum values of interactibilities (ratios of nonadditive genetic variances to phenotypic variances) and nonadditive correlations were somewhat smaller than heritabilities and additive genetic correlations. Sire additive and total direct and maternal genetic predictions for birth and weaning weight tended to increase with the fraction of Brahman alleles, whereas nonadditive direct and maternal genetic predictions were similar for sires of all Angus and Brahman fractions. These results showed that it is feasible to evaluate sires for additive and nonadditive genetic effects in a structured multibreed population. Data from purebred breeders and commercial producers will be needed to accomplish the same goal at a national level.
Citations
More filters
TL;DR: Estimates of genetic variation and predictions of expected progeny differences showed that Romosinuano animals competed well against Zebu and RZ crossbred animals under the tropical environmental conditions at Turipaná.
Abstract: Intrabreed additive genetic, environ- mental, and phenotypic variances and covariances for Romosinuano ( R ) and Zebu (Z), as well as interbreed nonadditive genetic variances and covariances (sire × breed-group-of-dam interactions), for birth weight (BWT), weaning weight (WW), and postweaning gain (GW) were computed using a Romosinuano-Zebu multibreed data set from the TuripanaExperiment Station in Colombia. Covariances were estimated with a sire-maternal grandsire model, using a multibreed REML procedure. The computing algorithm was a generalized expectation-maximization (GEM) al- gorithm. This algorithm yields no asymptotic standard errors as part of its computations. Because of the small size of the data set (2,546 calves), these REML covariance estimates should be viewed with caution. Estimates of intrabreed heritabilities were similar to the ratios of interbreed nonadditive to phenotypic variances (interactibilities) for direct and maternal effects of the growth traits evaluated in this study. Intrabreed heritability estimates for BWT, WW, and GW direct genetic effects were .16, .09, and .14, for R and .24, .10, and .14 for Z. Corresponding heritability values for maternal effects were .18, .09, and .23 for R and .14, .13, and .07 for Z. Interactibility estimates were .21, .05, and .12, for direct and .26, .04, and .11, for maternal BWT, WW, and GW. Negative correla- tions between additive maternal weaning weight and direct and maternal postweaning gain, as well as between environmental weaning weight and post- weaning gain, suggested that there was compensatory postweaning gain in this herd. Estimates of genetic variation and predictions of expected progeny differ- ences showed that Romosinuano animals competed well against Zebu and RZ crossbred animals under the tropical environmental conditions at Turipana ´ .
55 citations
TL;DR: The MBAM represents a viable alternative to AM for multiple-breed genetic evaluations, providing the necessary flexibility in modeling heteroskedastic genetic variances of breed composition groups.
Abstract: The primary objective of this study was to demonstrate the utility of a hierarchical Bayes implementation of a multiple-breed animal model (MBAM) to estimate breed composition means and additive genetic variances as well as on variances due to the segregation between breeds. The MBAM and a conventional animal model (AM) were both applied to five simulated data sets derived from each of two different populations. Population I consisted of crosses between two breeds having a twofold difference in genetic variance and a nonzero segregation variance. Population II had the same population structure as Population I, except that the two breeds had the same genetic variance with no segregation variance; that is, Population II was essentially single breed in its genetic architecture. For Population I, posterior means of all variance components obtained by MBAM were unbiased, with 95% posterior probability intervals (PPI) having the expected coverage based on five replicates. The MBAM showed a slightly superior performance over the AM for genetic predictions in Population I, although there was no evidence that the use of the MBAM translated into greater genetic gains relative to the use of the AM. Nevertheless, the MBAM was clearly demonstrated to have superior fit to the data using pseudo-Bayes factors (PBF) as the basis for model choice. As expected, the MBAM and AM performed equally well in Population II. A data set consisting of 22,717 postweaning gain (PWG) records of a Nelore-Hereford population (40,082 animals in the pedigree) also was analyzed. The MBAM inference on Nelore and Hereford additive heritabilities (h 2 A) substantially differed. Herefords had a posterior mean h 2 A of 0.20 with a 95% PPI of 0.15 to 0.25, whereas the corresponding values for the Nelores were 0.07 and 0.04 to 0.11, respectively. The posterior mean genetic variance due to the segregation between these breeds was 8.4 kg2, with a 95% PPI of 2.3 to 24.8 kg2, and represented 35.4% of the Nelore but only 9.9% of the Hereford posterior mean genetic variance. The posterior mean h 2 A using the AM was 0.15, presumed common across the two breeds, with a 95% PPI of 0.11 to 0.19. The PBF heavily favored the MBAM over the AM for the PWG data. Accordingly, the MBAM represents a viable alternative to AM for multiple-breed genetic evaluations, providing the necessary flexibility in modeling heteroskedastic genetic variances of breed composition groups.
51 citations
Cites background or result from "Covariance components and predictio..."
...These percentages were larger than those found for birth and weaning weights of crosses between Angus and Brahman in Florida, ranging from 1.4 to 3.1% (Elzo and Wakeman, 1998)....
[...]
...Even though existing prior information for segregation variances is limited (Elzo and Wakeman, 1998; Birchmeier et al., 2002), there is exten-...
[...]
TL;DR: Correlations between breeding values for WHH, WWT, and HH18 indicate that it will be possible to identify animals that will reduce, maintain, or increase hip height while weaning weight is increased, and if the breeding objective is to manipulate growth to 18 mo of age, implementation of multiple-trait breeding programs considering hip height and weight at weaning will help to predict hip height at 18Mo of age.
Abstract: Genetic parameters for weaning hip height (WHH), weaning weight (WWT), postweaning hip height growth (PHG), and hip height at 18 mo of age (HH18) and their relationships were estimated for Brahman cattle born from 1984 to 1994 at the Subtropi- cal Agricultural Research Station, Brooksville, FL. Re- cords per trait were 889 WHH, 892 WWT, and 684 HH18. (Co)variances were estimated using REML with a derivative-free algorithm and fitting three two-trait animal models (i.e., WHH-WWT, WHH-PHG, and WWT-HH18). Heritability estimates of WHH direct ef- fects were 0.73 and 0.65 for models WHH-WWT and WHH-PHG and were 0.29 and 0.33 for WWT direct for models WHH-WWT and WWT-HH18, respectively. Estimates of heritability for PHG and HH18 direct were 0.13 and 0.87, respectively. Heritability estimates for maternal effects were 0.10 and 0.09 for WHH for models WHH-WWT and WHH-PHG and 0.18 and 0.18 for WWT for models WHH-WWT and WWT-HH18, respec- tively. Heritability estimates for PHG and HH18 mater- nal were 0.00 and 0.03. Estimates of the genetic correla- tion between direct effects for the different traits were moderate and positive; they were also positive between WHH and WWT maternal and WWT and HH18 mater-
48 citations
Cites result from "Covariance components and predictio..."
...These estimates agreed closely with those (0.29 and 0.21) reported by Elzo and Wakeman (1998) but were slightly greater than those (0.23 and 0.16) aDiagonal: heritabilities (line 1) and additive genetic variances (line 2); above diagonal: additive genetic correlations; below diagonal: additive…...
[...]
TL;DR: Brahman genetics impacted not only the calpain-calpastatin system, but also muscle fiber size and metabolic properties, and Brahman-influenced cattle produced tougher steaks and exhibited decreased protein degradation.
46 citations
Cites methods from "Covariance components and predictio..."
...A diallel mating system was used in this multibreed herd, where sires from the six breed groups were mated across to dams of the same six breed groups (Elzo & Wakeman, 1998)....
[...]
TL;DR: Results indicated that crossbred animals with up to 50% Brahman showed limited negative impact on meat quality while maximizing meat yield due to heterosis.
46 citations
Cites methods from "Covariance components and predictio..."
...One important characteristic of the UF Angus-Brahman 170 multibreed herd (Elzo & Wakeman, 1998) is that Angus, Brahman, and Brangus sires from their 171 respective US populations, as well as ¾ A ¼ B, ½ A ½ B, ¼ A ¾ B crossbred sires from various 172 Southern states were used as artificial…...
[...]
...The mating design used in the multibreed herd was diallel (Elzo & Wakeman, 1998), 58 where sires from the six mating groups (Angus, ¾ A ¼ B, Brangus, ½ A ½ B, ¼ A ¾ B, and 59 Brahman) were mated across to dams from these same six mating groups....
[...]
References
More filters
49,597 citations
TL;DR: In this paper, the authors proposed a restricted maximum likelihood (reml) approach which takes into account the loss in degrees of freedom resulting from estimating fixed effects, and developed a satisfactory asymptotic theory for estimators of variance components.
Abstract: Recent developments promise to increase greatly the popularity of maximum likelihood (ml) as a technique for estimating variance components. Patterson and Thompson (1971) proposed a restricted maximum likelihood (reml) approach which takes into account the loss in degrees of freedom resulting from estimating fixed effects. Miller (1973) developed a satisfactory asymptotic theory for ml estimators of variance components. There are many iterative algorithms that can be considered for computing the ml or reml estimates. The computations on each iteration of these algorithms are those associated with computing estimates of fixed and random effects for given values of the variance components.
2,440 citations
66 citations
"Covariance components and predictio..." refers background in this paper
...A population composed of straightbred and crossbred animals that interbreed constitutes a multibreed population (Elzo, 1983, 1990b; Elzo and Famula, 1985)....
[...]
TL;DR: Beefmaster, Brahman, Brangus, and Santa Gertrudis field data records were used to determine genetic and environmental parameter estimates using a multiple-trait, pseudo-expectation approach, andBrangus weaning sheath and navel score heritabilities indicated that genetic change for the size and shape of the sheathand navel area is possible.
Abstract: Beefmaster, Brahman, Brangus, and Santa Gertrudis field data records were used to determine genetic and environmental parameter estimates using a multiple-trait, pseudo-expectation approach. Adjusted birth weight, 205-d weight, and postweaning gain records were analyzed for each breed. Also, Brangus weaning sheath and navel scores were both analyzed using a single-trait, pseudo-expectation method to determine genetic parameter estimates. Additive birth weight heritability (h2A) estimates ranged from .22 to .37 and maternal birth weight heritability (h2M) estimates ranged from .12 to .55. Estimates for 205-d weight h2A for the four breeds varied from .21 to .25, and 205-d weight h2M estimates ranged from .15 to .21. Postweaning gain h2A estimates ranged from .16 to .56. The genetic correlation between direct and maternal portions of birth weight was negative for all breeds. This was also true for the genetic correlation between direct and maternal portions of 205-d weight, except in Brahman cattle, for which it was .15. The genetic correlation between additive portions of birth weight and 205-d weight was large and positive in all breeds. A moderately positive correlation between 205-d weight and postweaning gain was found for all breeds except Santa Gertrudis, whereas the environmental correlation between these two traits was a small to moderately negative estimate in all breeds. Brangus weaning sheath and navel score heritabilities indicated that genetic change for the size and shape of the sheath and navel area is possible.
60 citations
"Covariance components and predictio..." refers methods in this paper
...…national beef cattle sire evaluations use intrabreed genetic prediction procedures, and comparisons of sires across breeds are computed using a table of correction factors obtained using experimental data from the Meat Animal Research Center (Notter and Cundiff, 1991; Van Vleck and Cundiff, 1996)....
[...]
TL;DR: Expected progeny differences from national cattle evaluation programs for sires of F1 calves and cows for BWT, WW, YW, and net maternal ability (milk) were used to assess their value in prediction of crossbred performance.
Abstract: Data on 2,034 F1 calves sired by Angus, Hereford, Polled Hereford, Charolais, Limousin, Simmental, Gelbvieh, and Tarentaise bulls with Hereford or Angus dams and data on 3,686 three-breed-cross calves with 700 F1 dams of the same breed crosses were used for this study. Traits analyzed were birth, weaning, yearling, and 420-d weights (BWT, WW, YW, and W420, respectively) of F1 calves and WW of three-breed-cross calves. Expected progeny differences from national cattle evaluation programs for sires of F1 calves and cows for BWT, WW, YW, and net maternal ability (milk) were used to assess their value in prediction of crossbred performance. Regressions of actual F1 calf performance on sire EPD were positive for BWT (1.09 +/- .12 kg/kg of BWT EPD), WW (.79 +/- .14 kg/kg of WW EPD), YW (1.44 +/- .16 kg/kg of YW EPD), and W420 (1.66 kg/kg of YW EPD). These regression coefficients were similar to the expected value of 1.0 for BWT and WW but were larger than expected for YW and W420. Regressions of actual three-breed-cross calf WW on milk and WW EPD of their maternal grandsires were .95 +/- .14 and .42 +/- .10 kg/kg, respectively, and differed little from their expectations of 1.0 and .5, respectively. Observed breed of sire means for each trait were adjusted for sire sampling by using EPD regressions to adjust them to the average EPD of all sires of each breed born in 1970.(ABSTRACT TRUNCATED AT 250 WORDS)
43 citations