|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 5/30/2000
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Three models were used to analyze mature weight records from three selection lines (weaning weight, yearling weight, index of yearling weight and muscle score and control) of Hereford cattle. Weights were measured three times per year; at brand clipping (BC), before breeding (BB), and at palpation (PA). All animal models included year x age x line, dam age x line, pregnancy status x line, and birth and method of rearing of calf x line as fixed effects, covariate for interval between calving and when weighted and a random permanent environmental effect of cow. Each of the three weights was analyzed separately with REML. The full model included maternal genetic and permanent environmental effects of dam. The second model included an overall effect of the dam. The third model contained no maternal effects. The three models were significantly different (likelihood ratio test). With the full model, parameter estimates for direct heritability (SE) were .79 (.09), .74 (.08), and .67 (.08) for BC, BB, and PA weights. Estimates for maternal heritability were .07 (.03), .12 (.03), and .11 (.03) and correlations between direct and maternal genetic effects were -.72 (.12), -.67 (.07), and -.63 (.09). Fractional variances due to permanent environmental effects were .00 (.06), .00 (.05), and .00 (.05) and of permanent environmental effects of dam of cow were .03 (.02), .05 (.02), and .06 (.02). Maternal effects appear to be of some importance for mature weight and therefore should be considered in models for genetic evaluation of mature weight.