The study was conducted in order to determine the influence of pro- and prebiotics on the live weight dynamics and the metabolism in breeding gilts. In a concluding physiological trial twelve pigsanalogues were used which were separated into four experimental groups (CG, EG1, EG2, EG3) three head each. It was established that the supplementation of the diets for the animals with the pro-prebiotic preparation "Primix Bionorm K" at the level of 0.45 kg/t (EG3), increased the average weight gain by 7.9%, which was demonstrated by the positive balance of both nitrogen and calcium. The quantity of the used nitrogen and calcium, ingested and digested, reached its maximum values in EG3; the indices were by 34.13 and 16.80%, and by 6.5 and 12.35%, respectively, higher compared to the indices on the control group (CG).