Management traits in dairy cattle. dystocia,udder characteristics related to production,and a review of other traits

The purpose of this paper is to present a short summary of our research on dystocia in Holsteins and a review of management trait information in North America.Primary selection emphasis should be on milk production and milk constituents. Management traits contributing to ease or economy of production should be selected only if economic importance and phenotypic and genetic relationships to productive traits justify such selection.Breeding efficiency is economically important; but, genetic improvement within breeds is difficult. Evidence indicates dystocia can be minimized by selecting sires for production, evaluating them for ease of calving, mating heifers to sires whose offspring are born easily without direct selection against dystocia. Selection against mastitis might be effective, but management practices can reduce the incidence of mastitis. Selection for udder and leg structure may be necessary in order to avoid problems concerning economical food production. Speed of milking has economic importance and it responds to selection. The amount of emphasis for the selection of milking speed and the most efficient way to apply this has not been clarified. Additional study of the genetics of body-weight change is necessary in order to maximize feed conversion. Genetic control of metabolic disorders is not now feasible; management control is necessary. Dairymen desire amenable cows, but heritability estimates for this trait are low. Measures of temperament need improvement. The economic worth of all management traits should be further quantified.