|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Early life weights of beef cattle may be influenced not only by genes transmitted to a calf by it's sire and dam but also by the maternal genetic ability of the dam to care for and furnish milk for the calf. Maternal influence may be different with different management systems and for different breeds. This study of maternal influence involved about 10000 records of the Korean Native Cattle (Hanwoo) for weight at birth, at weaning (four months) and six months. An effect due to sire by region by year-season interaction was added to the model to determine the effect on heritability and the direct maternal genetic correlation with the interaction effect in the model. Direct heritability decreased from .15 to .09, .14 to .03, and .14 to .02 for birth, weaning and sex-month weights with little change in maternal heritability even though the interaction variance was small (.02 to .04 of total variance). The direct-maternal genetic correlation also increased dramatically for those traits; .23 to .61, -.44 to .11, and -.35 to .40. This result, when considered with other studies, suggests that serious misidentification of sires and/or dams may be a reason for why such a small fraction of variance associated with sire by region interaction can have such a large effect on estimates of genetic parameters needed for national genetic evaluations. One conclusion is that more effort is needed to secure better pedigree information for Hanwoo cattle.
Technical Abstract: Data of Korean Native Cattle from Rural Development Administration of Korea were used to estimate genetic parameters for birth (BW, n=10,889), weaning at 120-d (WW, n=8,637), and six month weight (W6, n=8,478) needed for genetic evaluations. Number of animals in pedigrees was 14,494. Estimates were obtained with REML. Estimates of heritability for BW, WW, and W6 analyzed as single-traits were .09, .03, and .02 with full model which included direct and maternal genetic, maternal permanental environmental effects, and effects due to sire by region by year-season interaction, respectively. Estimates of maternal heritability for BW, WW and W6 were .04, .05, and .07. Ignoring the interaction effects in the model resulted in much larger estimates for direct heritability than with interaction in the model. Estimates of direct-maternal genetic correlation were positive for BW, WW, and W6 with full model but were negative without the interact- ion for WW and W6. Estimates of direct genetic correlations between BW an WW, BW and W6, and WW and W6 were large: .52, .45, and .90, respectively. Genetic correlations were large and positive for maternal effects for BW with maternal effects for WW and W6 (.69 and .74), and for WW with W6 (.97). Log likelihoods were the same for models including grandmaternal effects as for models including maternal effects for all traits which indicates that grandmaternal effects are not important for these traits or that data structure was not adequate for estimating parameters for a grandmaternal model.