EXPANDING THE POSSIBILITIES OF PHENOMICS IN DAIRY CATTLE SELECTION PROGRAMMES

The methodology of modern selection programmes in dairy cattle breeding is effectively implemented in reference animal populations that are genotyped and phenotyped for a large number of traits. Such a data set is critical for selection because it provides a basis for assessing and predicting the breeding value of young animals in a number of areas. At the same time, it can be linked to the nutritional value of milk (medical aspect) and the efficiency of feed protein utilisation by cows, which is an important economic component of dairy production. The paper discusses the medical aspects of the impact of milk urea nitrogen (MUN) and residual nitrogen on the formation of the microbiota of consumers of such milk and the associated consequences for their health. The possibilities of assessing MUN as an important predictor of feed nitrogen efficiency (MNE) in milk production are considered. A statistically significant regression dependence of MUN on MNE in milk production (b = –2.495 ± 0.209) was found. To select the best animals, it is recommended to evaluate them within the optimal range of MUN values of 8–12 mg/dl, at which higher MNE values and more efficient milk production are observed. Low MUN values (< 8–10 mg/dl) may indicate a protein deficiency in the diet, which is often associated with a decrease in rumen microorganism activity and, accordingly, may lead to reduced milk productivity and milk protein synthesis.