UTILIZATION OF POOR QUALITY ROUGHAGES BY SHEEP: EFFECTS OF ALFALFA SUPPLEMENTATION ON RUMINAL PARAMETERS, FIBER DIGESTION AND RATE OF PASSAGE FROM THE RUMEN

Abstract

Barley straw, bromegrass hay and corncobs were fed with or without alfalfa supplementation to six sheep in a 6 × 6 Latin square design in order to investigate the effects of alfalfa supplementation in the ruminal digestion of untreated poor-quality roughages. Alfalfa supplementation increased ruminal concentrations of valerate and isobutyrate (P < 0.05) for corncobs and of isobutyrate (P < 0.05) for barley straw. In addition, ruminal ammonia-N levels were increased by supplementation (P < 0.05) for all diets. This improvement in the rumen environment was reflected by increase (P < 0.05) in sacco rates of fiber digestion which were 4.63 and 5.85%/h, 4.73 and 6.18%/h, 3.78 and4.57%/h, without and with alfalfa, respectively, for barley straw, bromegrass hay and corncobs. For corncob diets, rates of passage of indigestible material were increased by supplementation from 1.87%/h to 3.06%/h (P < 0.05). These results explain some of the associative effects on digestion that have been noted between poor and good quality roughages. Key words: Roughage quality, sheep, digestion kinetics, fiber passage, rumen parameters, supplementation