title: Effects of isoacids, urea, and sulfur on ruminal fermentation in sheep fed high fiber diets.
abstract: The effects of isoacids, urea N, and S on ruminal fermentation of sugarcane bagasse- or corn stover-based diets were studied in sheep. Acetate production was taken as a measure of the fermentation rate. For the sugarcane bagasse diet, neither urea nor S supplementation changed ruminal acetate production. When N and S were combined, acetate production was 44% higher (3.16 vs. 2.18 mol/d). Similar effects were noted for the corn stover diet. Increasing the level of isoacids from .1 to .2 g/kg BW per d in the diet did not change acetate production for either diet. However, N supplementation of the sugarcane bagasse diet containing the low level of isoacids resulted in a 49% greater acetate production (2.86 vs. 1.91 mol/d). Acetate production was 90% higher (3.74 vs. 1.97 mol/d) when the diet containing the high level of isoacids was supplemented with N. The corresponding increases for corn stover were 12% (2.64 to 2.95 mol/d) and 35% (2.88 to 3.87 mol/d). The results suggest that NH3 N provided by the basal diet was more limiting than isoacids. Once the N deficiency was corrected, isoacids became limiting. Ruminal digestion of high fiber diets low in N was improved by supplementation with urea, isoacids, and S.
authors.affiliation: Department of Animal Science, Michigan State University, East Lansing 48824.
authors.forename: A
authors.initials: A
authors.lastname: Brondani
authors.forename: R
authors.initials: R
authors.lastname: Towns
authors.forename: K
authors.initials: K
authors.lastname: Chou
authors.forename: R M
authors.initials: RM
authors.lastname: Cook
authors.forename: H
authors.initials: H
authors.lastname: Barradas
mesh_terms: D000085:Acetates / Q000378:metabolism; D000818:Animals; D002087:Butyrates / Q000494:pharmacology; D004043:Dietary Fiber / Q000378:metabolism*; D005285:Fermentation; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology; D012756:Sheep / Q000378:metabolism*; D013455:Sulfur / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology; D014631:Valerates / Q000494:pharmacology
chemical_list: D000085:Acetates; D002087:Butyrates; D004043:Dietary Fiber; D014631:Valerates; D013455:Sulfur; D014508:Urea