Dependence of cow reproduction status on the productivity and the quantity of lactation periods
Reproductive functions of cows depending on milk productivity and the number of lactation periods, as well as the reasons of reproductive impairments, were studied using regular gynecological examinations. It was found that reproductive function impairment in cows is increased with the growth of milk productivity with the complication reaching maximum in 43% of cows for 6 and more lactation, and the length of the service period amounts to 145 days with the average value of insemination index being equal to 3.2. During lactation periods up to 1 and 2 the average frequency of reproductive impairment in cows is 21%. The analysis of research materials concerning reproductive activity of examined cows of black-and-white breed in the conditions of the Republic of Bashkortostan shows that the main reason of decrease in breeding performance lies in the presence of ovary hypofunction which can amount to 37.1%, cysts - 15.2% in highly productive herds, and 34.5% of persistent yellow bodies - in those with low productivity. The use of bioregulator complexes allows achieving rather high values of cows coming in heat - from 74 to 91% of animals from the total quantity. The highest values of successful insemination (up to 75%) were registered in cows during lactation periods 3 and 4. Examination found that improvement of milk productivity leads to the increase in reproductive function impairment rate. According to our information, the number of cows with gynecological diseases in highly productive herds was higher than in those with low productivity by 2.1 times.