A comparative study of nutrient digestibility, kinetics of degradation and passage and rumen fermentation pattern in goats and sheep offered good quality diets

The in vivo digestibility, the rates of fermentation and passage and the rumen fermentation pattern were compared in Granadina goats and Segurena wethers fed alfalfa hay (AH), alfalfa hay/sugar beet pulp. 4:1 (AH/SB) and alfalfa hay/sugar beet pulp/oat grain, 3:1:1 (AH/SB/OG) at approximately maintenance level. The animals were at stall and no selectivity was practised. The nylon bag technique was used to estimate the extent and fractional rate of degradation of the feed in the rumen. The fractional outflow rate of particles was determined with chromium as a marker. No significant interspecies differences in the nutrients digestibility were found. Values of potential and effective degradability and rates of degradation of both dry matter and protein were similar in goats and sheep. Also, the calculated values of the fractional rate of passage of the digesta out of the rumen were not significantly different between animal species. Ammonia-N concentrations were higher in the rumen liquor of goats than in sheep. No clear trend in the concentration of total and individual volatile fatty acids was observed when comparing goats and sheep with the exception of an increased proportion of valeric acid in the rumen liquor of sheep. From present and previous trials it is concluded that goats and sheep show equal capacities of digestion of medium to good quality diets when fed at energy maintenance level and feed selection is absent. This would validate extrapolations of feed evaluations, what implies a unique energy value. (C) 2000 Elsevier Science B.V. All rights reserved.