Growth and development of replacement heifers depending on the origin

Abstract

For insemination of cattle’s broodstock, the bulls’ seed is used, both domestic and foreign selection, that is, the increase in blood count of received heifers for the Holstein breed continues. The growth of animals, despite general growth patterns, is influenced by many factors, including their origin. The research aim is to assess weight growth characteristics of replacement heifers, depending on their origin, namely the father – the servicing bull. It was found that the difference in live weight at birth between heifers of different seed bulls was insignificant and amounted to 1.4 kg or 4.7%. The highest live weight at 18 months of age had heifers from the Sayan bull – 425.3 kg, slightly 3.6-5.3 kg inferior to them were the heifers from the Cassio and Mers bulls. Heifers grew unevenly over the periods. The uneven growth of heifers of different seed bulls, although it has a general pattern, but differs in groups. If in the period from 6 to 12 months of age there is a decrease in absolute growth in all groups, then already in the next period we can note the peculiarities in absolute growth change. So, the absolute growth of the heifers from the Das bull remained at the same level; the absolute growth of the heifers from the Sayan, De-Su, Tuareg, Cassio bulls continued to decline, and the absolute growth of the heifers from the seed bulls Havano, Mers and Bentley increased. On average, for the entire growing period, it ranged from 21.0 to 22.0 kg per month. Thus, the culture system of replacement heifers on the farm allows to get good results. The age of the first heifers’ insemination, depending on belonging to the seed bull, ranges from 14.3 to 16.9 months, which allows us to speak about using early terms of the first heifers’ insemination. The live weight at the time of the first insemination meets the requirements.