The experiment presented here was undertaken to investigate the effect of infusion level of casein into the abomasum on the nitrogen metabolism of goats fed a basal diet of hay.
The following results were obtained.
1. The calculated casein digestibility was 86.5-89.0% when 60 g of casein was adminis tered into the abomasum and the retention of casein nitrogen was 2.0-2.5 g per day. The utilization of infused-casein nitrogen was calculated as 27-34%.
2. When 90 g of casein was additionally infused into the abomasum, the digestibility of casein was calculated as 85.6-95.1%. As a result, 1.9-2.5 g of infused-casein nitrogen was retained in the body, and the calculated utilization of casein nitrogen was 16-22%. These results suggest that there is a certain limit on nitrogen retention when more nitrogen than the requirement is provided.