Heritability, Phenotypic and Genetic Correlations between Type Ratings and Milk and Fat Production in Holstein-Friesian Cattle

Abstract

Intra-sire, intra-herd variance and covariances of daughters and dams were used to estimate heritabilities, and phenotypic and genetic correlations between type ratings and milk and milk fat production records adjusted to a single record basis. Milk and milk fat production records and official type classification ratings of 14,727 Holstein-Friesian cows and their dams were included in this study. Heritability estimates for milk and milk fat production were of the order of 0.20, and did not differ significantly among the three levels of herd production. The estimates of heritability for type ratings ranged from 0.03 for dairy character to 0.31 for rump. Phenotypic correlations between type ratings and milk and milk fat production ranged from +0.02, to +0.25, with a standard error of 0.01 to 0.02. Most of the genetic correlations concerning type ratings and production were not significant. The genetic correlations between dairy character and production were significant and ranged from 0.61 to 0.82 for the three stratified groups. Selection based on type ratings, with the exception of rating for dairy character, would cause little genetic improvement in milk or milk fat production. The relative genetic progress in milk production, if selection is on dairy character, is expected to be 35 to 50% of that which can be obtained by selecting on the basis of one milk production record. © 1961, American Dairy Science Association. All rights reserved.