Impact of genomic selection on health improvement of high-yielding cows

Abstract

The use of selection in dairy cattle breeding, focused for many decades on increasing milk productivity and technological properties of milk (fats and proteins), has led to the health problems of cows, including a decrease in the reproductive function, the prevalence of lameness, metritis, mastitis, infectious lesions of hooves, ketosis, milk fever and others (on average, from 30,0 % to 70,0 %). Calves, which are born by high-yielding cows in their early postnatal period, are characterized by a high mortality rate due to diarrhea (56,0 %) and respiratory diseases (47,0 %). The mortality of young animals and the forced culling of cows are global problems in the world of dairy farming. As a result, there is an interest in disease resistance breeding of dairy cattle, given that only healthy animals have an economic value, being effective and profitable. The purpose of this article was to provide some information on the global trends in the selection of dairy cattle. It is shown that genomic selection, which is originally used among bulls for their assessment and selection based on the productivity of offspring, is currently used to select female cattle by predicting their own further productivity. At the same time, the current direction of selection is a new group of economically significant breeding traits related, inter alia, to animal health, when all traits are assessed together (milk productivity, fat production, protein production, number of live calves produced, incidence of mastitis, lameness, metritis and other signs). The level of genomic selection's reliability is shown, which is 49,0 %, achieved as a result of developments begun in 2016 on the use of genomic selection, taking into account the indicated signs of health. The task is to improve the reliability of estimates for a wide range of phenotypic traits that contribute to the profitability resulting from keeping dairy cows throughout their productive life.