Genetic Structure of Dairy Cattle Herds in Terms of Additive and Dominance Relationships

Abstract

These data indicate that the average additive relationship within herds is low. The dominance relationship is so low as to be essentially zero. Regardless of the magnitude of the dominance variance, and the variance due to interallelic interactions involving both genes of at least one pair, these components could, on the average, contribute little to the total genetic covariance between relatives in populations which approach so closely the breeding structure of random-mating populations. Also, the genetic differences between the herds which arise from the relationship of contemporary animals indicate that for butterfat production the heritability of differences between herds averages is of the order of 5%, when differences in ideals and intensities of selection are not considered.