INFLUENCE OF SOME PARATYPIC FACTORS ON THE QUALITY OF RAW MILK OF HOLSTEINIZED COWS
We have studied the fractional composition of different sources is difficult-degradable protein (rapeseed, soybean, corn gluten, sunflower meal) and their impact on the quality of raw milk of highly productive cows of holsteinized black-motley breed. The research was conducted in the stud farm "Pushkinskoye" Nizhny Novgorod region, where purebred Holstein cattle is bred. Balancing protein in the diets of high-producing cows was carried out with extruded soybean and rapeseed, corn gluten, sunflower meal. Inclusion in diets high protein feed (rapeseed, soybean, and corn gluten) contributed to the increased milk production on average by 6,5-8,5% compared with groups of cows on commercial diet (sunflower meal). The synthesis of milk protein was significantly increased in soybean and corn groups by 11-13% (p<0,05), while maintaining the basic technological properties. The yield of milk fat was significantly higher in cows kept on diets with extruded soybeans, the advantage compared with controls was 9% (p<0,05). The increase of the mass fraction of fat in the milk of cows occurred in "rapeseed" and "corn" groups by 0,33 and 0,23 % respectively. According to the obtained results the inclusion in rotations system of the Middle Volga region such non-traditional forage crops, as rapeseed, soybeans, corn for grain will solve the problem of protein diet of high-producing cows with a precise balance of degradable and unsplittable in the rumen protein. For the rational use of nitrogen-containing substances of the diet, maintaining high milk production and increase the yield of milk protein it is necessary to ensure the receipt of these forages in the amount of 9-10% of dry matter in extruded form and in the form of gluten. With the aim of improving the quality of raw milk in the processing it into cheese and full-fat cottage cheese it is recommended to include extruded soybeans and corn gluten as a source of hard-degradable protein in diets of cows. This will reduce the consumption of milk per 1 kg of cheese and cottage cheese by 0,88 kg and 0,54 kg, respectively. In the processing of milk into butter - use extruded soybeans and rapeseed in diets of cows, which helps to reduce the flow of milk for 1 kg of product by 0,54 and 1,77 kg compared with the control.