Weaning weight, gain on test, and feed consumption of the beef cattle herd at the San Juan Basin Research Center were analyzed with the reduced animal model. Only males were scored for gain on test and feed consumption. Of the 5145 animals with valid records for weaning weight, only 1463 had valid records for all three traits. Random effects were direct genetic effects for these three traits and maternal genetic and environmental effects on weaning weight. Fixed effects were inbreeding level and birth year for all three traits and effects of sex and dam’s age and inbreeding level on weaning weight. Because animals that were not parents were absorbed into parents’ equations, total number of mixed model equations was only 8095 compared with 22,111 for the complete model. Genetic effects of nonparents were derived by back solution. Variance and covariance components were estimated by Henderson’s Method 3. A sire model was used to estimate direct genetic and environmental variance and covariance components. Maternal variance components for weaning weight were estimated with a model that included effects of sire, dam, and maternal grandsire. For all three traits, genetic trends were positive, and environmental trends were not significant. Genetic correlation between gain on test and feed consumption was .8

J. I Weller, R. L Quaas, J. S Brinks

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XIII. Plenary lectures, molecular genetics and mapping, selection, prediction and estimation., , 390–393, 1990
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