Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Animal Science

Major Professor

John C. Waller

Committee Members

Kelly R. Robbins, Alan G. Mathew, James W. Bailey, Richard N. Heitmann


Experiments were conducted to define the degradation kinetics of purified fiber products compared to conventional feedstuffs. In situ analysis was conducted on soybean hulls, dried distillers grains, dried corn gluten feed, rice mill, wheat middlings, solka floc, oat fiber (200 and 300 series), corn bran, red and white wheat bran using nylon bags. In situ results determined oat fiber (300) and solka floc were most similar to soybean hulls and secondly to corn gluten feed. An oat fiber: solka floc mixture was formulated for subsequent experiments. The in vitro experiment consisted of alfalfa hay, soybean hulls, corn gluten feed, oat fiber (300), solka floc, and 60% oat fiber: 40% solka floc. In vitro DM disappearance was greatest for soybean hulls followed by oat fiber, corn gluten feed, and the fiber mixture. In vitro gas production was greatest for soybean hulls, oat fiber, and the fiber mixture. Subsequently six cannulated steers and six wether lambs were arranged in replicated 3 x 3 Latin squares to determine effects of supplementing purified fiber to steers and lambs consuming tall fescue hay on nutrient disappearance, ruminal kinetics, and N balance. Free choice hay was supplemented with 40% solka floc: 60% oat fiber at 0, 0.25, or 0.50% of BW. Steer forage intake and total N intake were not affected by supplementation. Total intake of OM, NDF, and ADF increased with supplementation. Ruminal and total tract OM, NDF, and ADF disappearance increased with supplementation. Ruminal and total tract nitrogen disappearance were not affected by supplementation in steers. In lambs, organic matter, NDF, and ADF digested in the total tract was increased with supplementation. Total tract N digestion decreased, however, retention was not affected. In steers, ruminal acetate concentration tended to increase, butyrate increased, and propionate not affected by supplementation. Ruminal pH increased with supplementation. Ruminal NH3-N concentrations decreased with supplementation, but a treatment x time interaction existed. These data indicate that in both steers and lambs supplementing tall fescue hay diets with digestible fiber increases ruminal and total tract fiber digestion without affecting forage intake or digestion of nitrogen while also increasing ruminally available energy.

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