title: Effect of fiber-based creep feed on intake, digestion, ruminal fermentation, and microbial efficiency in nursing calves.
abstract: Six Angus crossbred cow-calf pairs (653 +/- 35 kg and 157 +/- 10 kg initial BW for cows and calves, respectively) were used to evaluate the influence of a fiber-based creep feed on intake, ruminal fermentation, digestion characteristics, and microbial efficiency in nursing beef calves. Cow-calf pairs were stratified by calf age and assigned randomly to one of two treatments: control (no supplement) or supplemented. Supplemented calves received 0.9 kg of a 49% soy hulls, 44% wheat middlings, 6% molasses, and 1% limestone supplement (DM basis) daily. All calves were cannulated in the rumen and duodenum and given ad libitum access to chopped brome hay (Bromus inermus L; 7.43% CP, 40.96% ADF, and 63.99% NDF; DM basis). Supplementation was initiated on May 1 (88 +/- 10.3 d calf age). Three sampling periods were conducted throughout the study (June 14 to 25, July 5 to 16, and August 9 to 20). Supplement and forage were offered at 0800 daily. Total, hay, and milk OM intakes of nursing calves were not affected by supplementation (2,014 vs. 2,328 +/- 288.8, 1,486 vs. 1,029 +/- 3,06.9, and 528 vs. 575 +/- 87.0 g/d, respectively). Milk OM intake was less (P < 0.09) in August than in June and July (635, 691, and 345 +/- 110.6 g/d for June, July, and August, respectively). A supplementation x month interaction occurred (P < 0.10) for total-tract OM digestion. Supplementation did not affect (P > 0.40) total-tract OM digestibility during June and August; however, during July, total-tract OM digestibility was lower (P = 0.03) for the control calves. Ruminal ammonia concentration, total VFA, and butyrate molar proportion increased (P < 0.05), whereas acetate proportion decreased (P = 0.01) in supplemented calves. Microbial efficiency was not influenced by supplementation (11.8 vs. 12.0 g/kg of OM truly fermented for control and supplemented calves, respectively). These data indicate that fiber-based supplements can be used as creep feed without negative effects on OM intake, total-tract OM digestibility, and ruminal fermentation characteristics in nursing beef calves.
authors.affiliation: Department of Animal and Range Sciences, North Dakota State University, Fargo 58105, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Soto-Navarro
authors.forename: M H
authors.initials: MH
authors.lastname: Knight
authors.forename: G P
authors.initials: GP
authors.lastname: Lardy
authors.forename: M L
authors.initials: ML
authors.lastname: Bauer
authors.forename: J S
authors.initials: JS
authors.lastname: Caton
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000833:Animals, Suckling / Q000502:physiology*; D002417:Cattle / Q000378:metabolism*; D004063:Digestion / Q000502:physiology*; D005247:Feeding Behavior; D005260:Female; D005285:Fermentation; D012417:Rumen / Q000382:microbiology* / Q000502:physiology*; D013997:Time Factors