Economic and useful traits of replacement heifers and first-calf heifers under different conditions of rearing and milk production

Abstract

In the modern world the technology of production becomes a decisive factor in the growth of the economic potential of all branches of animal husbandry, a profi table direction and object of application of capital and resources, an instrument of competition. Technology determines the level of intensity and effi ciency of production, its environmental safety, production quality, biological and nutritional value of food. In recent years, highly productive cattle of Black-and-White breed with a high proportion of blood of Holstein breed are used to produce milk. For expression of their genetic potential of productivity it is necessary to work out technology of rearing of replacement heifers as it is known that conditions of rearing have essential infl uence on further productivity of animals. From one-year-old heifers and heifers to 6-month pregnancy, the control group has been housed in a cell-group method on slotted cast-iron fl oors, and the experimental group has been housed in a loose-boxes technology. Diff erent ways of housing had an impact on the growth and development of animals. Heifers of the experimental group in the fi rst period of research from 12 to 15 months had a lower absolute gain in body weight, which has been associated according to our opinion with the stressful situation from the habituation of animals to each other, since the number of animals in the group has been increased by 2 times. However, by 18 months of age the live weight of heifers in the experimental group has reached the live weight of heifers in the control group, while they had a higher average daily gain by 45,1 g (P < 0,05). Further, the heifers of the experimental group were superior to the heifers of the control group. It has been established that the loose-boxes method of housing allows to increase labour productivity and accordingly the effi ciency of milk production.