Influence of soybean hull supplementation on rumen fermentation and digestibility in steers consuming freshly clipped, endophyte-infected tall fescue

• Published in: Journal of animal science Vol. 84; no. 3; pp. 678 - 685
• Main Authors: Richards, C. J, Pugh, R. B, Waller, J. C
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Soc Animal Sci 01-03-2006; American Society of Animal Science
• Subjects: ammonia; Ammonia - analysis; Animal Feed - analysis; Animal productions; Animals; Biological and medical sciences; Cattle - physiology; cattle feeding; Cross-Over Studies; Dietary Fiber - administration & dosage; Dietary Fiber - metabolism; Dietary Supplements; digesta; digestibility; Digestion - physiology; endophytes; Fatty Acids, Volatile - metabolism; feed intake; feed rations; feed supplements; Fermentation; Festuca arundinacea; forage grasses; Fundamental and applied biological sciences. Psychology; Glycine max - metabolism; Male; neutral detergent fiber; nitrogen; Nitrogen - metabolism; nutrient availability; Nutritive Value; organic matter; Poaceae - metabolism; Poaceae - microbiology; Random Allocation; Rumen - chemistry; Rumen - metabolism; rumen fermentation; rumen fluids; steers; Terrestrial animal productions; Time Factors; Vertebrates; Bovine; Digestive system; forage intake; Ox; Rumen; cattle; Soybean; Fermentation; Feeding; Grain legume; Vertebrata; Meat animals; Mammalia; Endophyte; Influence; Artiodactyla; Supplementation; Ungulata; Digestibility; tall fescue
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/2006.843678x

Six steers (288.6 ± 2.1 kg of BW) fitted with rumen and duodenal cannulas were used in a crossover design to evaluate intake, rumen fermentation, and site of nutrient digestion of freshly clipped, endophyte-infected (E+) Kentucky 31 tall fescue with or without soybean hull (SH) supplementation at 0.60% of BW (OM basis). Steers were placed in metabolism units within an environmentally controlled room and provided with free-choice access to fresh forage, water, and a vitamin/mineral supplement. The spring growth of E+ tall fescue was harvested daily during the experiment. Supplement was fed at 0700 with approximately 65% of the estimated daily forage. To maintain a fresh forage supply, additional forage was stored in a cooler and fed at 1900. Periods were 21 d with 14 d of adaptation and 7 d of digesta sample collection. Chromic oxide was used as a marker of duodenal digesta flow. Duodenal samples were taken 4 times daily with times shifting by 1 h each day to represent all 24 h of a day. Treatments were considered significant at P < 0.05. Supplementation of SH decreased forage OM intake from 1.64 to 1.41% of BW but increased total OM intake from 1.64 to 2.01% of BW. Apparent percentages (53.1%) and quantities (2,786 g/d) of rumen OM disappearance were not affected by supplementation. Percentages of total tract OM disappearance were not different (70.8%). Percentages of apparent rumen NDF disappearance also were not different (65.6%). Percentages of N disappearance were not different. Supplementation of SH resulted in increased total N (34.1 g/d) and microbial N (17.1 g/d) flowing to the duodenum. Rumen pH (6.5) was not affected, and rumen ammonia concentrations exhibited a time x treatment interaction in which SH decreased ammonia for 12 h after supplementation. Total VFA concentrations (103.9 mM) were unaffected. Liquid dilution rate (12.7%/h) and rumen OM fill (4.3 kg) were not different between treatments. Supplementation of SH at a rate of 0.60% of BW (OM basis) to calves consuming fresh E+ tall fescue decreased forage consumption but resulted in greater total intake, greater flow of N to the duodenum, and increased total tract OM disappearance.