Influence of milk quality on the growth of replacement heifers during the preweaning period of rearing

According to modern standards of rearing replacement heifers of Holstein breed, insemination is performed when they reach a live weight of 375–385 kg and the sooner the heifer reaches these parameters the sooner its fi rst calving will occur and consequently the animal will enter the main milking herd and begin to bring profi t. When inseminating replacement heifers at the age of 13–14 months they are input into the main herd at the age of 22–23 months. Obtaining such parameters becomes possible with the observance of detailed feeding standards for replacement heifers and the use of special feed additives that ensure the consumption of the required amount of dry matter with feed. In this case their growth and development are especially important during growth up to 6 months, i.e. the preweaning period of growth where the quality of colostrum and milk are of great importance. The purpose of the research was to study the influence of the composition and quality of milk of cows during the period of increasing of milk yield and during the period of fading of lactation on the growth and development of replacement heifers during the preweaning period of rearing. The results obtained in the course of a scientific and economic experiment on replacement heifers during the preweaning period of rearing to study the dependence of the chemical composition of milk on the growth of experimental animals have been presented in the paper. The experiment revealed that using milk from cows in the stage of fading lactation, it is possible to obtain a higher absolute gain in the live weight of heifers during the preweaning period (by 5.15 kg or 10.9 %) and an average daily gain of 875 g or 85.8 g higher than the same indicator for heifers fed with milk from cows in the increasing of milk yield stage of lactation.