Effect of degradable protein in cow diet on body systems’ physiological status

Abstract

The relationship between indicators of enzymatic and microbiological processes in the rumen and metabolism in the body was studied in lactating cows when the content of soluble protein in the diet was changed. The change in digestible protein content was provided by different ratios of natural feed and synthetic protein additives. The study was conducted on 3 lactating first-calf Holstein cows with rumen and 12 intestinal cannulas. The rate of fractional efflux from the complex stomach was evaluated by chromium oxide and microbial synthesis by purine bases. Experimental data were obtained to improve feeding rates, evaluate diets for high-yielding dairy cattle and develop rates of readily available carbohydrates in diets. At increase of share of soluble and degradable protein fractions in feed there is a natural increase of ammonia formation in rumen and urea content in blood and at achievement of ratio of degradable protein fractions and easily available carbohydrates in feed in the ratio of 0.44, there is maximum efficiency of microbial synthesis and supply with available amino acids of synthesis of milk components, which is proved by increase of concentration of amino acids in blood and formation of milk protein and promotes more complete realization of productive capacity of dairy cattle. Application to lactating cows of a ration with a higher ratio of degradable protein and DHC (higher than 0.44) reduces the efficiency of feed nitrogen utilization by reducing the efficiency of microbial protein synthesis by 10%.