Genetic Analysis of the Components of Type Conformation and Production in Ayrshire Cows

Abstract

The heritabili-ties of 10 components of type and final rating were estimated from approximately 1180 daughter-dam comparisons by doubling the intraherd regression of daughter''s single type score on dam''s single type score. The heritability estimates are: head and neck, 0.30; shoulders and chest, 0.15; middle and loin, 0.31; rump and thighs, 0.32; feet and legs, 0.18; udder size and shape, 0.08; udder attachments, 0.06; udder teats, veins and quality, 0.27; general quality, 0.13; breed character, 0.32; and final rating, 0.31. Single type and butterfat records were used to estimate the average within-herd phenotypic and genetic correlations between all combinations of the components of type, final type rating, and butterfat production. Records on 1273 cows were used to estimate phenotypic correlations, and 729 daughter-dam pairs were used to estimate genetic correlations. The phenotypic correlation between final type rating and butterfat production was estimated to be 0.08, and the corresponding genetic correlation was estimated to be -0.52. The weights which should be given to the records on each component of type and a single butterfat record on an animal when selecting for butterfat production were determined. Data indicate that in selecting for butterfat production alone nothing can be gained by giving positive emphasis to final type score.