The influence of Holstein crossbreeding on the reproductive qualities of Black-and-White cows

The purpose of the research was to study main indicators reproductive ability Black-and-White cows, depending on proportion Holstein genes. As material for there were taken data breeding and zootechnical records cows breed CJSC Semenovsky Breeding Plant Mari El Republic. results showed that with an increase in thorough-bredness improved. Thus, first-calf heifers a low genes (up 12.5 %) had latest age first fruitful insemination calving (21.9 months 32.3 months). With up 87.6 % more, decreased by 7.7 (31.8 %), - 7.4 month (21.8 fertility index increased 5.8 (14.6 %). At same time, duration service period high-blooded animals 18.8-26.4 days (15.8-23.8 interval all genetic groups exceeded optimal time changed accordance change period. longest degree (13.8 months), which 0.1-0.7 longer than other groups. There coefficient studied ‒ 0.91-0.93. significant influence (ɳ 2 = 9.57 8.80 1.98 (P≤0.05) established. effect genotype weak 0.09 ɳ 0.26 unreliable.