EFFECTS OF LEVEL OF PROTEIN AND TYPE OF MOLASSES ON DIGESTS KINETICS AND BLOOD METABOLITES IN SHEEP

Eight ruminally fistulated wethers were used in a replicated 4 x 4 lat in square to investigate the effects of level of dietary protein (10 o r 18%) and type of molasses (BM-sugarbeet molasses, or WSC-wood sugar molasses) on digesta kinetics and blood metabolites in sheep. Wethers were fed a basal diet of 70% chopped prairie hay: 30% chopped barley s traw (forage) and one of four treatment diets. Treatments were: (1) 10 % CP and WSC, (2) 10% CP and BM, (3) 18% CP and WSC, and (4) 18% CP an d BM. Diets were formulated to be iso-caloric using barley in the low protein diets to balance for energy. Soybean meal (SBM) was fed to mee t the 10% CP and 18% CP protein treatments. Response variables include d in vivo and in situ digestion, SBM and forage digesta kinetics, rumi nal VFA concentrations, and blood metabolites. Lambs fed WSC tended (P = 0.11) to have greater IVDMD, ruminal isobutyrate, and valerate than lambs fed BM. In situ SBM and forage rate of digestion, particulate p assage rates, retention time, intestinal transit time, total VFA conce ntration and acetate:propionate ratio did not differ between types of molasses (P > 0.20), Lambs fed the 18% CP diets consumed more feed, ha d a more rapid rate of SBM in situ digestion, lower ruminal pH, faster SBM and forage particulate passage, and lower SBM and forage retentio n time than lambs fed the 10% CP diet (P < 0.10). Total and individual VFA concentration were greater (P = 0.001) in lambs fed the 18% CP di et than lambs fed the 10% CP diet. Aspartate aminotransferase was grea ter in lambs fed BM than lambs fed WSC. Blood levels of creatinine, ch loride, calcium, protein, lactate dehydrogenase, and cholesterol were lower(P < 0.11), and triglycerides and blood urea nitrogen higher(P = 0.01) in lambs fed the 18% CP diet than those fed the 10% CP diet. Lev el of dietary protein exerts much greater influence on digestibility a nd blood metabolites than type of molasses. However, WSC appears to be a suitable replacement for BM given equal price structure. (C) 1998 E lsevier Science B.V.