EFFECTIVENESS EVALUATION OF RAPESEED CAKE ON MILK PRODUCTIVITY OF COWS IN THE FIRST PHASE OF LACTATION

The objective of the study is to determine the effectiveness of adding rapeseed cake to dairy cow diets during the first four months (122 days) of the first, second, and third lactations. Scientific and economic experiment was conducted at the Solyanskoye Experimental Farm in the Rybinsk District of the Krasnoyarsk Region on Red-and-White cows during the first to third lactations. Six experimental groups were formed: three control and three experimental groups, with 10 cows in each. The first control and experimental groups included first-calf heifers, the second group included second-lactation cows, and the third group included third-lactation cows. The average live weight of first-calf heifers was 503 kg, 559 kg in the second lactation, and 607 kg in the third. Rapeseed cake was the studied factor; it was introduced into the diet of cows in the experimental groups by replacing the same amount of concentrates at a rate of 20 %. The cows in all experimental groups were fed according to the required feeding standards, depending on their physiological condition and the planned productivity. The introduction of rapeseed cake into the diet allowed to increase the content of crude protein by 14.4–15.6 %, undigestible protein by 15.6–16.1, and cleavable protein by 11.4–15.6 % compared to the control groups. It also had a positive effect on milk synthesis processes: the gross milk yield of natural milk in cows in the experimental groups (first, second, and third lactations) increased by 3.0; 2.8; 2.6 %, milk fat by 4.1; 5.9; 6.2 %, and milk protein by 5.1; 5.2; 6.8 %, respectively, compared to the control groups. Feeding rapeseed cake to dairy cows of different age groups proved to be economically beneficial: revenue and profit from milk sales per head of cows in the experimental groups were higher than those in the control groups by 4.7, 5.5, 6.5, and 11.94, 12.7, and 14.3 %, respectively. Introducing rapeseed cake to the diet of dairy cows is rational from both a zootechnical and economic perspective.