OPTIMIZATION OF MICRONUTRIENT REQUIREMENTS FOR COWS OF THE HOLSTEIN BREED OF DOMESTIC SELECTION IN DRY, FRESH AND INCREASING MILK YIELD PERIODS

Abstract

Keeping Holstein cows on large mechanized farms negatively affects their health and productivity. High-yielding animals experience greater deficiency in mineral substances compared to mediumand low-yielding animals. It can be replenished with premixes introduced into the diet. This paper contains the results of research, the purpose of which was to conduct a comparative assessment of the effect of increased levels of minerals in the diets of cows of the Holstein breed of domestic selection in dry, fresh and increasing milk yield periods with general compound feeding on the course of pregnancy, milk productivity and milk quality, homeostasis, organic matter digestibility and nitrogen utilization. Studies showed that the use of moderately increased requirements for copper, zinc, manganese, cobalt, iodine and selenium in the diets of high-yielding animals with a predominance of bulky feed in relation to concentrates had a positive effect on the studied indicators. Thus, higher weight gain in the physiological dry period and increased growth energy of calves in the prophylactorium period were established. In fresh and increasing milk yield periods, daily yield of milk of standardized 4% fat content increased by 5.29 and 7.87%, milk protein yield – by 5.99 and 13.71%, organic matter digestibility and feed nitrogen utilization improved.