THE EFFECT OF FEED RATIONS ON THE PRODUCTIVITY OF HOLSTEIN-FRIESIAN BREED BULL CALVES
The article presents the results of scientific and industrial experience in identifying the effect of feed additives on the productivity and biochemical parameters of bull calves' blood in fattening. The calves of Holstein-Friesian breed at the age of 30 days were selected as objects of research. In the diet of the bull calves of the experimental groups, we used feed additives in the main diet: probiotic feed additive “Cellobacterin+”, feed vitamin-mineral concentrate “Tetra+”, complex feed concentrate. We found that the most active weight gain is observed in the group of calves that received complex feed concentrate. In all experimental groups of bull calves, we observed a decrease in the activity of hepato-indicator enzymes and a thymol sample. Based on the data obtained, it can be concluded that the use of the complex feed concentrate containing biologically active substances and the additive “Cellobacterin+” (in comparison with the control and other experimental groups) leads to maximizing the increase in the average mass of bull calves, which is associated with the synergistic effect of biologically active substances and living microorganisms Enterococcus faecium 1 - 35. The same tendency is observed with respect to the activity of hepato-indicator enzymes - AST and ALT, which, compared with the control group, decreases by 35.6% and 28.2%, respectively