ABSTRACT Data collected by the National Livestock Research Institute of the Rural Development Administration of Korea were used to estimate genetic parameters for yearling (YWT, n = 5,848), 18-mo (W18, n = 4,585), and slaughter (SWT, n = 2,279) weights for Korean Native cattle. Nine animal models were used to obtain REML estimates of genetic parameters: DP-2 included genetic, uncorrelated dam, and residual random effects; DQ-2 included genetic, sire × region × year-season interaction, and residual random effects; DPQ-2 was based on DQ-2 but included both interaction and dam effects; DMP-2 was based on DP-2 but with dam effect partitioned to include maternal genetic and permanent environmental effects; and DMPQ-2 was based on DMP-2 but also included sire interaction effects. Those five models included two fixed factors: region × year-season and age of dam × sex effects. Models DP-3, DQ-3, DPQ-3, and DMPQ-3 were based on DP-2, DQ-2, DPQ-2, and DMPQ-2 but included as a third fixed factor whether or not identification of the sire was known. Estimates of heritability with DMPQ-3 for YWT, with DPQ-3 for W18 and SWT when analyzed with single-trait analyses were .14, .11, and .17, respectively, and were nearly the same with bivariate analyses. Estimate of maternal heritability for YWT from single-trait analysis was .04, with estimates for other traits near zero. For bivariate analyses, the estimate for YWT was .01. With single trait analysis, estimate of the direct-maternal genetic correlation for YWT was negative (–.81). Estimates of direct genetic correlations between YWT and W18, YWT and SWT, and W18 and SWT were .99, 1.00, and .97, respectively. Estimates of environmental correlations varied from .60 to .81; the largest was between W18 and SWT. Including a fixed factor for whether sire identification was missing or not missing reduced the estimate of heritability for slaughter weight. The results suggest that the sire × region × year-season interaction is important for yearling weight and may be needed in a model for slaughter weight. Maternal effects may be of slight importance for yearling weight but of no importance for W18 and SWT. Models for national cattle evaluations for Korean Native cattle for YWT should be considered that include maternal genetic and permanent environmental as well as sire × region × year-season interaction effects, but those effects seem not to be needed for models for W18 and SWT. Not much reranking of sires occurred when ranked was based on the different models for W18 and SWT.
Implications
Maternal effects may not be needed in models for genetic evaluations for postweaning growth performance traits of 18-mo and slaughter weights of Korean Native cattle, but they may be of some importance for yearling weight. Including sire × region × year-season interaction effects in the model reduced estimates of heritability for yearling weight, which indicates that sire × region × year-season effects may represent contemporary group or herd effects, which, if confounded with genetic effects, would inflate estimates of heritability for yearling weight. Thus, recording herd identification should be encouraged in order to improve genetic evaluation. Estimates of direct genetic correlations among yearling, 18-mo, and slaughter weights were large enough that there would be no need to measure more than one of these traits. Accurate pedigree information is the basis for genetic evaluation, and further investigation targeting its improvement is recommended.
Key Words: Beef Cattle, Genetic Parameters, Growth
© 2000, by the American Society of Animal Science. All rights reserved.
J. Anim. Sci. 2000. 78:1414-1421
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