EFFECTS OF LIMITED INTAKE ON NITROGEN FLOW AND UTILIZATION IN DRY GOATS

Limited feeding effects (75% of ad libitum) were studied in 3 adult dr y goats. Their diet was composed of dried beet pulps (1/3 DM), dried a lfalfa (1/3 DM) and hay (1/3 DM). The CP content was 11.9% DM. Rumen f ermented OM was decreased by 243 g.d(-1), but rumen pH and ammonia con tent remained the same. Rumen bacteria synthesis efficiency was decrea sed (-4%), but the value (151 g crude bacteria protein.kg(-1) DOM) was higher than conventional values used in PDI and NRC systems. Nitrogen rumen balance (duodenal N-N intake) was lower (-1.9 g.d(-1)) with res tricted goats. This could be related to the increase in urinary urea e xcretion (+0.4 gN.d(-1)). There was no significant effect of the limit ing feeding on total OM and N digestibilities. The disappearance rate of OM in the rumen and the small intestine tended to be higher (+4 and +8%, respectively) in the restricted animals. Nitrogen retention was lower (-5.7 g.d(-1)) in restricted goats. Only 59 (or 56%) of the duod enal nitrogen was protein. Their digestibility in the small gut was hi gher (+8 pts) than NPN digestibility. A total of 86% of duodenal RNA d isappeared in the small gut but less than 60% of DAPA was digested in this part.