Influence of specific genetic and environmental factors on productivity of first-calf cows of Simmental breed

Milk productivity is the main indicator characterizing cattle. It is known that milk production indicators (milk yield, fat and protein content in milk) are determined by the animal's genotype and the environmental conditions in which it is realized. The aim of the research was to study the productivity of first-calf Simmental breed depending on certain genetic and environmental factors in the conditions of the Orel region. The studies were conducted in 2015-2018 on the basis of LLC Korotysh, Livensky district, Orel region. The data of accounting forms in dairy cattle breeding were analyzed: No. 2-mol. - card brood heifers, cows; No. 4-mol. - act of control milking; No. 10-mole. - log of insemination and calving cows. Also the information of system CELEKS was used. It was found that the rations of feeding first-calf cows satisfied their nutrient needs, and the process equipment did not have a significant impact on their milk production, i.e. conditions of detention were optimal. The farm uses animals of different lines, but the main ones are the lines Redad 711620016730, Reflection Sovereign, Montvic Chieftain, and Romulus 929189864. The live weight at birth in heifers of different lines was within 31.4-37.7 kg, at 18 months - 350.0-370.2 kg, live weight at the first productive insemination - 361.1-372.4 kg. The maximum milk yield for 305 days of lactation was obtained for 5096.5 kg cows from the Reflection Sovereign line, which is 2.3-10.4% higher than the yield of milk of other line cows. The values of weight content of fat and of weight content of protein in the milk of cows of different lines were 3.81-3.86% and 3.17-3.20%, respectively. The first-carved cows of the Redad 711620016730, Romulus 929189864 and Reflection Sovereign lines had an optimal dry period, but were characterized by a longer service period and, consequently, an increased calving interval. The reproductive qualities of the Montvic Chieftain cows met standards.