Analyses were carried out of the growth rate and concentration of some metabolites in blood serum of calves. The animals were fed diets supplemented with digest acid (a mixture of lactic, citric and orthophosphoric acids). It was shown that diet supplementation with this acid, used from calf birth till day 84 of life, had a beneficial effect on animal growth and increased uptake of the compound mixture already from day 22 of life. When the animals were fed only solid feeds, acid supplementation improved nutrient utilization, this being reflected in an increase in the concentration of some indices related to lipid, protein and carbohydrate metabolism.