A COMPARATIVE-STUDY OF NUTRIENT DIGESTIBILITY, KINETICS OF DIGESTION AND PASSAGE AND RUMEN FERMENTATION PATTERN IN GOATS AND SHEEP OFFERED MEDIUM QUALITY FORAGES AT THE MAINTENANCE LEVEL OF FEEDING

The in vivo digestibility and the rates of degradation and passage of alfalfa hay (AH) and vetch straw (VS) were compared in three Granadina goats and three Segurena wethers Fed at approximately maintenance lev el, using a change over design. The nylon bag technique was used to es timate the fractional rate of degradation of the feeds in the rumen. T he fractional outflow rate of hay and straw particles was determined w ith chromium as a marker. No significant differences in the digestibil ity coefficients of nutrients between animal species were found. Nitro gen retention expressed as coefficients of both nitrogen intake and di gested nitrogen was lower (P < 0.01) in goats than in sheep when VS wa s offered. There was no significant difference between goats and sheep in the effective degradability (measured at outflow rates in the rang e of 0.027 to 0.032 h(-1)) of dry matter (DM) for either forage. Howev er, the effective degradabilities of the neutral detergent fibre (NDF) and crude protein (CP) of VS were lower (P < 0.01 and P < 0.001, resp ectively), in goats than in sheep. The degradation rates of DM, NDF an d CP were not significantly different (P > 0.05) between goats and she ep. Also, the fractional rate of passage of particles from the rumen w as not different (P = 0.056) between species, although there was a ten dency for an increased outflow rate in goats. In a second experiment t he effects of animal species, type of diet and frequency of feeding on rumen fermentation pattern were studied following a factorial design. Four goats and four wethers were used. They were randomly allocated t o three dietary treatments: AH, VS or a 50:50 mixture of AH and VS (AH /VS). Rations were offered in two or three meals daily and samples of rumen content were obtained at 09.00, 11.00, 13.00, 15.00, 17.00 and 1 9.00 h. No difference in rumen pH was found between goats and sheep. T otal volatile fatty acids and ammonia concentrations were higher (P < 0.001) in sheep than in goats. The molar proportions of acetate and is ovalerate were higher (P < 0.01 and P < 0.001, respectively) in goats than in sheep, whereas the opposite was true for the molar proportion of n-butyrate. Feeding frequency had a slight effect on the rumen para meters measured. It is concluded that only minor differences in the di gestive capacity and rumen activity of sheep and goats can be expected when they are fed on medium quality forages.