Influence of altering ruminal degradation of soybean meal protein on in situ ruminal fiber disappearance of forages and fibrous byproducts

• Published in: Journal of animal science Vol. 73; no. 8; p. 2428
• Main Authors: Hussein, H S, Cameron, M R, Fahey, Jr, G C, Merchen, N R, Clark, J H
• Format: Journal Article
• Language: English
• Published: United States 01.08.1995
• Subjects: acide gras volatil; acido graso volatil; alfalfa; aliment pour animaux; ammonia; ammoniac; amoniaco; Animal Feed - analysis; Animals; Avena - chemistry; Avena - metabolism; beef cattle; boeuf; bovin de boucherie; buey; bullocks; Cattle - metabolism; Cattle - physiology; cellulolyse; cellulolysis; Cellulose - analysis; Cellulose - chemistry; Cellulose - metabolism; celulolisis; crop residues; degradacion; degradation; Dietary Fiber - metabolism; dietary fibres; digestion; Digestion - physiology; ensilado; ensilage produit; feed intake; feeds; Fermentation; fibra de la dieta; fibre alimentaire; foin; ganado de carne; Glycine max - metabolism; grillage; hay; heno; Hydrogen-Ion Concentration; ingestion de piensos; lucerne; luzerne; mais; maiz; maize; Male; Molasses - analysis; paille de ble; paja de trigo; piensos; Polysaccharides - analysis; Polysaccharides - chemistry; Polysaccharides - metabolism; prise alimentaire animaux; proteinas; proteine; proteins; residu de recolte; residuos de cosechas; roasting; rumen; Rumen - metabolism; Rumen - physiology; silage; soja; soybean meal; soybeans; tortas de soja; tostado; tourteau de soja; Triticum - chemistry; Triticum - metabolism; volatile fatty acids; wheat straw; Zea mays - chemistry; Zea mays - metabolism
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/1995.7382428x

The objective was to determine the effects of altering ruminal CP degradation of soybean meal (SBM) by roasting (Exp. 1) on ruminal characteristics and extents of in situ disappearance of DM, OM, and fiber components (Exp. 2). A control diet (8.2% CP) containing oat hulls, corn silage, starch grits, ammoniated corn cobs, and molasses was supplemented to 17.1% CP with unroasted SBM (SBM-0) or SBM roasted at 165 degrees C for 75, 150, or 210 min (SBM-75, SBM-150, and SBM-210, respectively). In Exp. 1, SBM was incubated for 0, 2, 4, 8, 12, 16, and 24 h in the rumen of two steers that were fed the SBM-0 diet. Extents of ruminal CP degradation and rates of N disappearance decreased (P < 0.05) linearly with increasing roasting time of SBM. In Exp. 2, five ruminally cannulated steers were used in a 5 X 5 Latin square design and were fed the five diets listed above during five 11-d periods. On d 11, five substrates (alfalfa hay, orchardgrass hay, corn silage, soy hulls, and wheat straw) were incubated in the rumen for 24 h. Extents of in situ disappearance of DM, OM, and fiber (NDF, ADF, cellulose, hemicellulose, and total dietary fiber) were analyzed as a split-plot design. No substrate X diet interaction (P >0.05) was observed for any of the measurements evaluated. Extents of in situ disappearance (24 h) of DM, OM, and fiber were highest (P <0.05) when the control diet was fed and were lowest (P <0.05) when the SBM-0 diet was fed. Decreasing the availability of SBM protein in the diet by roasting increased (P <0.10 extents of in situ disappearance of DM, OM, and fiber linearly. These extents were similar for steers fed the control diet or the diet containing SBM-210. Ruminal concentrations of NH3 N, branched-chain VFA, and valerate were highest (P < 0.05) and ruminal pH lowest (P <0.05) when the SBM-0 diet was fed. Results indicated a rapid ruminal fermentation of both protein and readily available carbohydrates of SBM (resulting in pH below 6.0) during the first 4.5 h afte.