Influence of inbreeding on the early maturity of replacement young Holstein breed
The paper considers the features of growth and development of repair heifers obtained as a result of the use of different degrees of inbreeding. Comparison of the intensity of growth of inbred heifers with their outbred peers showed the superiority of inbred young over outbred in live weight at the age of 0, 3, 6, 9, 12, 15 and 18 months by 3.7-7.0% (P>0.95; 0.999). In age periods 0-3, 3-6, 6-9, 9-12, 12-15, 15-18 and 0-18 months in inbred heifers, the average daily gain in live weight was higher than that of outbred heifers, by 6,1-8,9% (P>0.99; 0.999). At the same time, the differences in relative live weight gain between the experimental groups of animals were almost always insignificant and statistically insignificant (P<0.95), except for the period of 9-12 months, when the relative live weight gain in inbred heifers was higher, than in outbred heifers, by 22.7% (P>0.999). To determine how effective the selection for a breeding trait, carried out among young animals, will be, it is necessary to calculate the repeatability coefficient, the value of which for such a trait as live weight in inbred heifers was higher than in outbred animals. Having calculated the coefficients of heritability of live weight and the average daily increase in live weight, it was found that in inbred heifers in all age periods they were higher than in outbred peers.The age of reaching the optimal live weight for the first insemination in inbred heifers was 513.5 days, which is 38.7 days (P>0.99) less than in outbred peers, which implies that inbred animals have better early maturity than outbred heifers, here.