Influence of live weight of replacement heifers on their subsequent milk productivity
The article presents the results of studies on the influence of the replacement heifers` live weight on their subsequent milk production. When determining the optimal options for replacement heifers growing on the farm and the possibility of predicting milk productivity at an early age, it was revealed that in terms of milk fat (MF) the best indicators of milk productivity (MF per lactation - 351 kg) for the first lactation were animals with the live weight of 181-190 kg at the age of six months, and for full-aged cows (MF for lactation - 423 kg) - with that of 200 kg or more. Regardless of the level of live weight in different age periods, the mass fraction of protein in milk in the groups does not have a significant difference. The best indicators for the first lactation in terms of milk fat (MF - 347 kg) were found in cows with the live weight of 320-330 kg at 12 months of age, and for full-aged cows (MF for lactation - 435 kg) - with that of 350 kg or more with a lower (by 0.8-1.1 months from the average) age of the first insemination and the first calving. The level of live weight at the first insemination of 400 kg or more allows having the lowest age of the first insemination (15.2 months) and the first calving (25.5 months). Milk productivity per the first lactation in terms of milk fat (359 kg) was found in animals with the live weight at the first insemination of 441-460 kg, and in full-grown animals - (436 kg) - with that of 421-440 kg.