Abstract. The purpose of the research is to determine the optimal amount of neutral and acid-detergent fiber in the diets of cows during the first phase of lactation, contributing to an increase in milk production. The energy supply of highly productive cows depends largely on the consumption and degree of digestion of structural carbohydrates. The optimal amount of Neutral Detergent Fiber (NDF) in the diets of cows affects optimal physiological state – the stimulation of merycisin, saliva to maintain buffering in the rumen, increasing productivity, that is, improving the efficiency of fodder use. According to some scientists (E.L. Kharitonov, etc.), the 35–40% content of NDF in the diets of cows is optimal in the first 100 days of lactation with a productivity of 6,500 kilos of milk. In conditions of the Murmansk Oblast, the study of accessibility to digestion of NDF and ADF (Acid Detergent Fiber) taking into account the influence of their quantity and quality on the physiological state and milk productivity of cows was carried out for the first time. The study was carried out among two groups of Holstein-Kholmogory cows with 8 heads each: experimental and control group. A complete zoo-technical analysis of fodder using traditional methods with determining NDF and ADF. It has been established that some fodders with a high content of NDF have a higher energy value than those with a low content of NDF. In silage of perennial grasses, the content of NDF varies in the range from 14.35 to 23.71% at close values of disintegration in the rumen. The content of NDF in silage of perennial grasses is higher by 8.4% than in silage of annual grasses. It has been determined that the reduction of NDF in the diet of experimental cows to 37.0% increases the digestibility of nutrients in the diet, normalizes nitrogen metabolism, increases microbiological activity in the rumen, increases productivity. The obtained data can be used for the development of diet programs for highly productive cows to satisfy the physiological needs of animals to realize the genetic potential of milk production
Keywords
accessibility, diet, highly productive cows, crude fiber, neutral detergent fiber, acid detergent fiber, digestibility