The role of structural carbohydrates in feeding of cows in the conditions of the european north

The purpose of the research is to study effect of quality of neutral detergent (NDF) and acid detergent (ADF) fiber with its different content in the rations when feeding of high productive cows on the digestibility of nutrients, use of the fodder nitrogen by animals, their productivity. The experiment was carried out on Holsteined cows of the Kholmogory breed during the second phase of lactation (101-200 days) on two groups selected according to the principle of paired analogues - control and experimental, 9 heads each, with a productivity of 8-10 thousand kg per year. The ration of the control group cows corresponded to the economic one. It contained crude fiber - 18.8%, neutral detergent fiber - 42.0%, acid detergent fiber - 21.7% by dry matter. The ration of cows of the experimental group contained crude fiber - 21.7%, neutral detergent fiber - 45.0%, acid detergent fiber - 23.2%. Due to the change in the ratio of bulky feeds (hay, silage) in the ration, different levels of NDF and ADF were created. As a result of the conducted research, it was found that feeding of animal by foods with neutral detergent fiber up to 45.0% and acid detergent fiber up to 23.2%, microbiological activity in the rumen of cow is increasing, the digestibility of nutrients in the ration is increasing, nitrogen metabolism is improving. As a result milk productivity is increasing by 7.0%, milk fat by 0.08%. Maintenance of high productive cows on ration with the level of NDF - 45.0% and ADF - 23.2% makes it possible for more fully stabilization of metabolic processes in animal body, to improve the intensity of rumen digestion, and use feed efficiently. Acknowledgment: This work was carried out within the framework of the state assignment of the Ministry of Science and Higher Education of the Russian Federation on the topic No. FGER-2021-0001, registration number AAAA-A19-119011790116-7. We would like to express our gratitude to the staff of LLC "Polar Star", Murmansk Region, for their assistance in conducting the research.