title: Comparative ruminal and total tract digestion of a finishing diet containing fresh vs air-dry steam-flaked corn.
abstract: Ten Holstein steers (465 +/- 6 kg) with cannulas in the rumen and proximal duodenum were used in a crossover design experiment to evaluate the influence of air-dry vs fresh steam-flaked corn on characteristics of ruminal and total tract digestion. The basal diet contained 77% steam-flaked corn (DM basis). Air-dry steam-flaked corn (SFC-AD) was obtained from a single batch that had been allowed to air-dry for 5 d before beginning the trial. Fresh steam-flaked corn (SFC-F) was produced daily Monday through Friday. Following production, the SFC-F was placed in air-tight polybags and stored at 4 degrees C until the time of feeding. There was little difference (P > .20) between SFC-AD and SFC-F with respect to site and extent of digestion of OM, starch, and fiber. Moreover, the two treatments did not differ (P > .20) in ruminal degradability of feed N. Apparent total tract N digestion was slightly greater (2.4%, P < .05) for SFC-F than for SFC-AD. Treatments did not affect ruminal pH (P > .20); however, VFA concentration of ruminal fluid tended to be greater (8.3%, P < .10) for SFC-F than for SFC-AD, indicating that the initial rate of fermentation may have been greater with SFC-F. Ruminal molar proportions of acetate were not affected by treatments (P > .20), but ruminal molar proportions of propionate tended to be greater (9.7%, P < .10) and molar proportions of butyrate tended to be less (10.0%, P < .10) for SFC-F than for SFC-AD. We conclude that the characteristics of digestion and the feeding value of steam-flaked corn is not altered by air drying before feeding.
authors.affiliation: Department of Animal Science, Imperial Valley Agricultural Center, University of California, El Centro 92243, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Zinn
authors.forename: R
authors.initials: R
authors.lastname: Barrajas
mesh_terms: D000818:Animals; D002417:Cattle; D003430:Cross-Sectional Studies; D004032:Diet / Q000592:standards / Q000662:veterinary*; D004040:Dietary Carbohydrates / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism; D004068:Digestive System Physiological Phenomena; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005511:Food Handling / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D012417:Rumen / Q000502:physiology*; D003313:Zea mays / Q000378:metabolism* / Q000592:standards
chemical_list: D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D009584:Nitrogen