An animal model and DFREML were used to estimate genetic and residual (co)variance components for backfat depth in different herds and for herds grouped by different levels of intraherd backfat variance. Estimates of genetic variance ranged from 1.39 to 9.78 and estimates of residual variance ranged from .88 to 7.05. Additive genetic and residual variances were clearly heterogeneous across herds and SD groups. The genetic component of variance in the high group was more than four times greater than that in the low group. Heritability estimates for backfat ranged from .35 to .73 across herds. Heritability estimates between high, medium and low SD groups were not significantly different. The extent of heterogeneity was such that a potential influence on sire evaluation would be expected. Estimates of genetic correlations between SD groups indicate that sires would be ranked differently in different SD groups and that genetic by SD group interactions did exist.

M. T See

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 17. Genetics and breeding of dairy and beef cattle, swine and horses, , 409–412, 1994
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