The influence of environmental factors on the dairy productivity of cows

Abstract

Among the paratype factors that influence the formation of dairy productivity of cows, a special place belong to the "herd-year-season", whose consideration abroad is necessary for the correction of milk yields and other important breeding characteristics. While exploring the impact of the above factors on the future dairy cow's productivity, it should be noted that these factors alone cannot directly affect yields, fat and protein content in milk, but indirectly the development of any quantitative feature depends on the conditions created for growing young animals, especially feeding and keeping depending on the year. Considering the stated purpose of our research was to study the effect of year and season of birth and first calving on dairy productivity of cows in high-yielding herds (average milk yield for a cow about 10,000 kg). Researches were carried out on cows of herds of LLC "Veleten" of Sumy oblast (n=1956) and public joint-stock company "Pleyzavod "Stepnoy" of Zaporizhzhia region (n=1981), created by the absorption of crossbreeding of cows of the Ukrainian Black-and-White dairy breed with Holstein breeders. Based on a retrospective analysis of zootechnical data (Uniform-Agri dairy herd management program) and the results of their own cows calving from 2004 to 2017, they studied dairy productivity, depending on the year and season of birth and calving. In the control herds, intergroup differentiation by cows' milk yield for the first and higher lactation was established, depending on the above factors. In both farms, the best milk yields were first born in 2015 and calved in 2017, and for higher lactation cows year 2012 and 2014 the first calving.  Comparison of group averages in the herd of LLC "Veleten" shows that the cows of the spring season of birth were characterized by the highest yields for the first lactation, but for higher lactation more milk was obtained from cows born in autumn. In public joint-stock company “Breeding Plant "Stepnoy” the influence of the birth season on the milk yield of the first-born cows was more significant and significant. At the same time, higher milk yields for both lactations studied were animals born in the summer. No significant difference was observed in such important breeding grounds as fat content and protein in milk between cows from different seasons of birth. The best milk yields in both controlled herds were characterized by first-borns who calved in the summer or in the autumn, with higher lactation in LLC "Veleten" – animals with summer calving season, and in PJSC "Breeding Plant "Stepnoy" – in winter. The year of birth (depending on the farm and the feature – 1,9–42,5%) and the year of first calving (1,6–41,2%) of the first births had the most significant impact on the milk productivity of the firstborn.  The birth season and the first calving season had a much smaller effect on the studied features, which, in our opinion, is explained by the uniform provision of animals with complete diets throughout the year. The influence of the herd factor on the milk productivity of the first-borns, though insignificant, but on the variability of milk yield, the amount of milk fat and milk protein, its level was highly reliable.