title: Effects of concentrated separator by-product (desugared molasses) on intake, site of digestion, microbial efficiency, and nitrogen balance in ruminants fed forage-based diets.
abstract: In Exp. 1, 4 ruminally and duodenally cannulated beef steers (444.0 +/- 9.8 kg) were used in a 4 x 4 Latin square with a 2 x 2 factorial treatment arrangement to evaluate the effects of forage type (alfalfa or corn stover) and concentrated separator byproduct (CSB) supplementation (0 or 10% of dietary DM) on intake, site of digestion, and microbial efficiency. In Exp. 2, 5 wethers (44 +/- 1.5 kg) were used in a 5 x 5 Latin square to evaluate the effects of CSB on intake, digestion, and N balance. Treatments were 0, 10, and 20% CSB (DM basis) mixed with forage; 10% CSB offered separately from the forage; and a urea control, in which urea was added to the forage at equal N compared with the 10% CSB treatment. In Exp. 1, intakes of OM and N (g/kg of BW) were greater (P < 0.01) for steers fed alfalfa compared with corn stover. Steers fed 10% CSB had greater (P < 0.08) OM and N intakes (g/kg of BW) compared with 0% CSB-fed steers. Total duodenal, microbial, and nonmicrobial flows of OM and N were greater (P < 0.01) for steers fed alfalfa compared with corn stover. Steers fed 10% CSB had increased (P = 0.02) duodenal microbial flow (N and OM) compared with 0% CSB-fed steers. Forage x CSB interactions (P < 0.01) existed for total tract N digestibility; alfalfa with or without CSB was similar (67.4 vs. 69.5), whereas corn stover with CSB was greater than corn stover without CSB (31.9 vs. -23.9%). True ruminal OM digestion was greater (P < 0.09) in steers fed alfalfa vs. corn stover (73.0 vs. 63.1%) and in steers fed 10 vs. 0% CSB (70.3 vs. 65.8%). Microbial efficiency was unaffected (P > 0.25) by forage type or CSB supplementation. In Exp. 2, forage and total intake increased (linear; P < 0.01) as CSB increased and were greater (P < 0.04) in 10% CSB mixed with forage compared with 10% CSB fed separately. Feeding 10% CSB separately resulted in similar DM and OM apparent total tract digestibility compared with 10% CSB fed mixed. Increasing CSB led to an increase (linear; P < 0.02) in DM, OM, apparent N digestion, and water intake. Nitrogen balance (g and percentage of N intake) increased (linear; P < 0.08) with CSB addition. Feeding 10% CSB separately resulted in greater (P < 0.01) N balance compared with 10% CSB fed mixed. Using urea resulted in similar (P = 0.30) N balance compared with 10% CSB fed mixed. Inclusion of CSB improves intake, digestion, and increases microbial N production in ruminants fed forage-based diets.
authors.affiliation: Animal and Range Sciences Department, North Dakota State University, Fargo, ND 58105, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Lawler-Neville
authors.forename: S M
authors.initials: SM
authors.lastname: Shellito
authors.forename: T D
authors.initials: TD
authors.lastname: Maddock
authors.forename: M L
authors.initials: ML
authors.lastname: Bauer
authors.forename: G P
authors.initials: GP
authors.lastname: Lardy
authors.forename: T C
authors.initials: TC
authors.lastname: Gilbery
authors.forename: J S
authors.initials: JS
authors.lastname: Caton
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D004063:Digestion / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D008297:Male; D008965:Molasses; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D009584:Nitrogen