Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 23, 1996
Publication Date: N/A
Birth weights (B) and calving difficulty (C) scores (1 to 7) on calves of nine pure and three composite breeds from the germ plasm utilization project at MARC were divided by first parity (1) and third and greater parity (3). About 6000 first and 11000 later parity records was analyzed. An animal model including random direct (D) and maternal (M) genetic, permanent maternal environmental, and residual environmental effects as well as fixed year-sex effects was used to obtain REML estimates of variances and covariances for four pairs of traits (C1,B1), (C3,B3), (C1,C3), and (B1,B3). Average estimates of genetic correlations were: .59 for (DC1,DC3), .57 for (MC1,MC3), .89 for (DB1,DB3), and .76 for (MB1,MB3). Average estimates from purebred and composite analyses were similar. Ranges over all breeds were large for estimates of genetic correlations, especially between direct and maternal effects. Heritability estimates of direct and maternal effects were larger for first parity calving difficult scores (.30 and .26) than for later parity scores (.16 and .08). Average estimates of direct and maternal heritability for B1 were .41 and .17 and for B3 were .52 and .11. Direct genetic correlations for (C1,B1) and (C3,B3) were .68 and .50 and for maternal genetic correlations were .34 and .36.