title: Supplemental cracked corn or wheat bran for steers grazing endophyte-free fescue pasture: effects on live weight gain, nutrient quality, forage intake, particulate and fluid kinetics, ruminal fermentation, and digestion.
abstract: Two experiments were conducted with beef steers (Exp. 1, average BW of 580 kg; Exp. 2, average BW of 247 kg) to evaluate the use of no supplements (CON) or daily supplementation with (OM basis) .34% of BW of cracked corn (CORN), .34% of BW of wheat bran (WBBW), or .48% of BW of wheat bran (WBISO; calculated to be isocaloric to CORN) on digestive responses (Exp. 1) and live weight gain (Exp. 2). In Exp. 1, type of supplement did not affect (P > .10) the dietary fiber or N constituents, but in vitro OM disappearance of the forage differed (P < .10) with supplementation and type of supplement fed. Supplemented steers consumed less (P < .05) forage and total OM. Particulate passage, fluid passage, and ruminal pH were not affected (P > .10) by supplementation. Ruminal NH3 N concentration showed (P < .05) a treatment x sampling time interaction and, in general, WBBW and WBISO steers had greater ruminal NH3 N than CORN and CON steers. Total VFA concentrations and molar proportions of propionate were lower (P < .10) in CON steers than in supplemented steers; no differences were noted (P > .10) among supplemented steers. Molar proportions of acetate were lower (P = .01) in supplemented steers than in CON steers and were greater (P = .03) in WBBW steers than in WBISO steers. Butyrate molar proportions were lower (P < .05) in CON steers than in supplemented steers and differed (P < .10) with type and quantity of supplement supplied. In situ forage NDF disappearance at 6, 9, and 24 h after feeding and rate of disappearance were greater (P < .05) in CON steers than in supplemented steers. In Exp. 2, CON steers weighed less (P = .01) than supplemented steers, CORN steers weighed more (P = .08) than wheat bran-supplemented steers, and WBISO steers weighed more (P = .02) than WBBW steers; ADG for 90 d followed a similar response. Results suggest that supplementation of wheat bran rather than corn did not seem to stop the reduction in forage intake or OM digestion associated with corn supplementation.
authors.affiliation: School of Veterinary Medicine, University of Nevada, Reno 89557-0104, USA.
authors.forename: B W
authors.initials: BW
authors.lastname: Hess
authors.forename: L J
authors.initials: LJ
authors.lastname: Krysl
authors.forename: M B
authors.initials: MB
authors.lastname: Judkins
authors.forename: D W
authors.initials: DW
authors.lastname: Holcombe
authors.forename: J D
authors.initials: JD
authors.lastname: Hess
authors.forename: D R
authors.initials: DR
authors.lastname: Hanks
authors.forename: S A
authors.initials: SA
authors.lastname: Huber
mesh_terms: D000641:Ammonia / Q000032:analysis; D000821:Animal Feed / Q000592:standards*; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004063:Digestion / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005285:Fermentation; D005527:Food, Fortified; D006863:Hydrogen-Ion Concentration; D008297:Male; D009584:Nitrogen / Q000032:analysis; D012417:Rumen / Q000737:chemistry / Q000502:physiology*; D014908:Triticum / Q000592:standards; D015430:Weight Gain / Q000502:physiology*; D003313:Zea mays / Q000592:standards
chemical_list: D005232:Fatty Acids, Volatile; D000641:Ammonia; D009584:Nitrogen