Reproductive qualities and milk productivity of cows having different average daily gains

The article presents the research results on the influence of weight gain rate of black-and-white replacement heifers on lowering the first insemination age and subsequent milk productivity. With an average daily gain of 800 g or less, the first insemination age has been at the highest level, equaling to 17.5 months with a live weight of 417 kg; the subsequent milk productivity has been 8893 kg during the first lactation and 10933 kg during the 3rd lactation and older. In the groups of heifers with the highest weight gain rate with an average daily gain of 901-1000 g and more than 1000 g, the heifers have been inseminated at the youngest age of 14.6 and 13.7 months with a live weight of 412 kg and 425 kg. The lowest milk yield (8060 kg) during the first lactation as well as during the 3rd and older (9682 kg) has been in the 4th group of cows with the highest average daily gain from the birth to the first insemination, more than 1000 grams.