Improvement of amino acid nutrition to reduce nitrogen excretion in lactating dairy cows.

摘要

The chapters included in this 40-page publication discuss the advances in milk production and the expansion of dairy herds in Japan in recent years. The relationship among faeces, urine, nitrogen excretion and feed intake; effects of ruminally protected amino acids and fish meal supplementation on milk yield, milk composition, and blood components; and the effects of adding fish meal to grass silage-based diets in order to reduce nitrogen excretion without affecting milk production. It was found that the ratio of total digestible nitrogen to crude protein in diets influences urine nitrogen as well as urine volume. Urea-N in milk and serum may be used as indices of urinary N excretion. Ruminally protected amino acids or fish meal supplementation supply amino acids that limit milk protein synthesis and increase milk protein contents when cows are fed grass silage-based diets. Supplementation with fish meal tends to reduce dietary CP without reducing milk production and decreases urinary nitrogen excretion.