|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/1999
Publication Date: N/A
Interpretive Summary: Weights of beef cattle after one year of age are not often analyzed. Weights at one year, at 18 months, and slaughter (about 22 months)were available for Han Woo (the Korean Native Cattle). Maternal effects of the dam were found to be important for yearling weight but not for weights after one year of age. For yearling weight, failure to include effects for interaction of sire by region by year-season inflated the estimate of direct heritability from .14 to .23, of maternal heritability from .04 to .07 and the direct-maternal genetic correlation from -.80 to -.91. A similar pattern has been found in other studies of weaning weight in Hereford and Angus cattle. Neither maternal genetic or sire by region by year-season interaction effects were important for 18 month and slaughter weights. The genetic correlations among the three post-weaning traits ranged from .89 to 1.00 which indicates little reason to obtain weights at more than one of those times. Models for genetic evaluation for yearling weight of Korean Native Cattle should include effects for both maternal genetic and sire by region by year-season interaction. Those effects do not seem needed for models for genetic weights at 18 months and slaughter.
Technical Abstract: Data from the National Livestock Research Institute of Korea were used to estimate genetic parameters for yearling (YWT, n=5,848), 18 month (WT18, n=4,585), and slaughter (SWT, n=2,279) for Korean Native Cattle. Estimates of genetic parameters by REML were obtained for 9 animal models. All models included direct genetic and residual effects. Other models included some or rall of the following: maternal genetic and permanent environmental as well as sire by region by year-season (SYRS) interaction effects. Five models (1-5) included two fixed factors: region x year-season and age of dam x sex effects. Models 6, 7, 8 and 9 included as an additional fixed factor whether or not identification of the sire was known. Estimates of heritability with best models for YWT, WT18, and SWT when analyzed with single-trait analyses were .14, .11, and .17, respectively and nearly the same with bivariate analyses. Estimate of maternal heritability for YWT from single trait analysis was .04 with estimates for the other traits nea zero but for bivariate analyses the estimate for YWT was .01. For multiple trait analyses, estimate of the direct-maternal genetic correlation for YWT was strongly negative (-.81). Failure to include fixed effect for whether sire identification was known increased magnitude of estimates of heritability and direct-maternal correlation for YWT. Estimates of genetic correlations between YWT and WT18, YWT and SWT, and WT18 and SWT were large: 1.00, .89, and .97, respectively. These results suggest models for national cattle evaluations for Korean Native Cattle for YWT should consider maternal genetic and permanent environmental and SRYS interaction effects but that these effects seem not to be needed for WT18 and SWT.