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Limited feeding effects (75% of ad libitum) were studied in 3 adult dry goats. Their diet was composed of dried beet pulps (1/3 DM), dried alfalfa (1/3 DM) and hay (1/3 DM). The CP content was 11.9% DM. Rumen fermented OM was decreased by 243 g.d-1, but rumen pH and ammonia content remained the same. Rumen bacteria synthesis efficiency was decreased (-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 restricted goats. This could be related to the increase in urinary urea excretion (+0.4 gN.d-1). There was no significant effect of the limiting 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 duodenal nitrogen was protein. Their digestibility in the small gut was higher (+8 pts) than NPN digestibility. A total of 86% of duodenal RNA disappeared in the small gut but less than 60% of DAPA was digested in this part.

A restriction in intake (75% of ad libitum) did not modify significantly the disappearance of energy in the rumen, the small and the large intestine. It decreased the N disappearance in the small intestine. Microbial synthesis was between 48 and 62 g N/kg of organic matter apparently degraded in the rumen.

The voluntary food intake, organic matter, crude protein and crude fiber digestibility and nitrogen balance of 23 diets have been measured simultaneously using 5 to 7 wethers and 5 to 7 castrated billy-goats in digestibility trials. The goats ate more than the wethers (58 vs 46 g DM/kg W0.75). The digestibilities obtained for goats were highly correlated with those obtained for wethers, and the mean values were similar in both species: Organic matter: digestion coefficient (CUD)goats = 1.22 CUDwethers -14.5 r = 0.93 Crude protein: digestion coefficient (CUD)goats = 1.07 CUDwethers -4.8 r = 0.94 Crude fiber: digestion coefficient (CUD)goats = 0.56 CUDwethers +29.6 r = 0.78 The mean nitrogen balance for goats (226 mg/kg W0.75) was significantly higher than that of wethers (152 mg/kg W0.75). Based on the regression equations for each species, the calculated efficiency of proteins digestible in the intestine (PDI) was 55 p. 100, the endogenous urinary nitrogen 160 mg/kg W0.75 and the nitrogen maintenance requirement 1.8-1.9 g of PDI/kg W0.75.