STUDY OF MILK PRODUCTIVITY OF COWS DEPENDING ON THE CLASSES OF DISTRIBUTION BY LIVE WEIGHT OF THE YOUNG

Abstract

The article examines the analysis of productive qualities of cows of the Ukrainian black-spotted breed depending on the live weight of repair heifers at the time of birth and first insemination. Classes of distribution of heifers by live weight at the time of birth were M – up to 35 kg, M0 – 36–42 kg, M+ – 43 kg and more. Distribution by live weight of heifers at first insemination was M – up to 354 kg, M0 – 355–426 kg, M+ – 427 kg and more. There is no significant influence of the live weight of heifers at birth on their future milk productivity. The first-borns, which had the lowest weight at birth, reached a milk yield of 7 432,35 kg in 305 days of lactation and slightly exceeded their peers of the M0 and M+ classes by 90,54 and 44,53 kg, respectively, by 2,53 and 0,70 kg and milk protein by 3,64 and 1,30 kg, respectively. A positive relationship was established between milk yield during the first lactation and live weight in all age periods of early ontogenesis in all groups of animals of different levels, except for animals of the modal class at 3 and 6 months of age (r = −0,065…−0,114) with the opposite direction dependence of minor strength and M+ class at birth (r = −0,249). There is a fairly strong correlation between live weight throughout the entire age period and the milk yield of firstborns born with the lowest live weight (r = +0,436…+0,523), between live weight and the age of the first insemination of animals (r = +0,596…+0,638), between live weight at the first insemination and milk yield (r = +0,298…+0,332), between milk yield of cows and average daily gain (r = +0,329). It was established that the first-borns inseminated with a live weight of 427 kg and more had the highest indicators of milk productivity. Nadia for 305 days of lactation of this group of animals was 8600 kg with milk fat – 312 kg and milk protein – 283 kg. The advantage in terms of milk yield and milk fat compared to the group of animals with average and low live weight for the first fertile insemination amounted to 18,6 and 24,5 %, respectively, and for milk protein – 19,6 and 27,5 %. First-borns inseminated with a live weight of up to 354 kg wer e characterized by lower milk productivity.