The use of new sources of by-pass protein in the cow diets to optimize milk production and herd reproduction performance indicators in modern economic conditions is relevant. The article presents data on the use of a protein concentrate containing plant and animal components and its effect on the quality of the milk obtained, the state of the rumen bacterial community and reproduction indicators. The use of protein concentrate of both 1.0 kg and 1.5 kg/head/day contributed to improving the quality and increasing the yield of dry matter of cow's milk by 0.17-0.43 %. During the days in milk, with the use of protein concentrate it was observed that increase the content of Selenomonas by 1.7 % and 4.1%, which cleave the urea, indicates a more efficient use of nitrogen in the diet. The inclusion of protein concentrate in the composition of daily diets helps to improve reproduction indicators, reduce the duration of the service period and the number of semen doses spent.