Problems in cow evaluation and current use of cow index. Report of a working group on cow evaluation

Abstract

A survey has been made by the study group of present utilization of cow indices that are considered important for efficient cow selection. Among other problems the following are considered most important and should therefore receive greater attention in index constructions and related research: • - the aggregate genotype should be properly and equally defined for both cows and bulls when calculating the index weightings for different sources of information; • - the effects of expressing yield in absolute vs relative terms at various yield levels: • - methods of evaluating the genetic merit of the individual herds and considering the genetic trend of the population; • - comparing the effects of different methods of adjustment for environmental factors including construction of herd average; • - the effects of environmental correlations between the cow and her dam; • - ways of testing the efficiency of different cow index constructions.