Specific features of the effect of different doses of complex B vitamins (thiamine hydrochloride, riboflavin, niacin, pyridoxine hydrochloride, folic acid, ciankobalamin in venous blood) on carbohydrate metabolism (glucose, concentration of lactic and pyruvic acids in the venous blood) at the final stage bull fattening. Studies have shown that the addition to the diet of calves for fattening balanced nutrients and minerals and fat-soluble vitamins A, D, E complex of B vitamins (В1, В2, В5, В6, В10, В12) in appropriate doses generally positive effect on carbohydrate metabolism, and the value of content in the venous blood glucose, lactic and pyruvic acids dose-dependent additionally introduced into the diet of B vitamins (В1, В2, В5, В6, В10, В12). The biggest change in terms of carbohydrate found in animals 3rd ((В1 0,040; В2 0,06; В5 1,2; В6 0,25; В10 0,0030; В12 0,0006 mg / kg body weight) and 4th (В1 0,070; В2 0,10; В5 2,0; В6 0,40; В10 0,0050; В12 0,0010 mg / kg body weight) research groups, and smallest in bull 1st (В1 0,015; В2 0,03; В50,5; В6 0,10; В10 0,0012; В12 0,0002 mg / kg body weight) and 2 th (В1 0,025; В2 0,04; В50,8; В6 0,15; В10 0,0020; В120,0004 mg / kg body weight) research group, which is associated with dose introduced to the diet of calves during the final fattening phase of B vitamins (В1, В2, В5, В6, В10, В12).