Cecava M J, Parker J E
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907.
J Anim Sci. 1993 Jun;71(6):1596-605. doi: 10.2527/1993.7161596x.
The objective of this study was to examine the effect of combining ruminally degradable and undegradable CP sources on ruminal microbial protein synthesis and postruminal N and amino acid (AA) flows in steers. Six steers fitted with ruminal, duodenal, and ileal cannulas were fed diets containing corn silage and high-moisture corn supplemented with urea, soybean meal (SBM), dry corn gluten feed (DCGF), a combination of corn gluten meal and blood meal (CB), or SBM and DCGF in combination with CB. Estimated ruminal N escapes for SBM, DCGF, and CB were 32, 25, and 68%, respectively. Supplemental CP sources supplied 35 to 40% of diet CP (12.5% CP diets). Dry matter intake was adjusted to 2.3% of BW for each steer in each period. Total N flow at the duodenum decreased (P < .01) when the diet was supplemented with urea vs other proteins due to decreased (P < .01) flow of nonmicrobial N. However, microbial N and AA flows were greater (P < .05) for urea than for other protein supplements. Disappearance of OM and NDF in the stomach decreased (P < .07) or was numerically lower but nonmicrobial N at the duodenum increased (P < .08) as CB replaced SBM or DCGF in the diet. Protein source had little effect on ruminal fermentation characteristics except that ruminal ammonia N (NH3N) concentration was higher (P < .05) for urea than for other treatments. Total AA and essential AA flows to and disappearance from the small intestine increased (P < .06) as CB replaced DCGF. However, substituting CB for SBM had little effect on intestinal flows and disappearance of AA. These data suggest that source of ruminally degradable CP can influence the efficacy of feeding ruminally degradable and undegradable CP in combination. In general, source of supplemental CP had a greater effect on the quantity than on the profile of absorbable AA supplied to the duodenum.
本研究的目的是考察将瘤胃可降解和不可降解粗蛋白来源相结合，对阉牛瘤胃微生物蛋白合成以及瘤胃后氮和氨基酸（AA）流量的影响。给六头安装了瘤胃、十二指肠和回肠瘘管的阉牛饲喂含有玉米青贮和高水分玉米的日粮，日粮中补充了尿素、豆粕（SBM）、干玉米麸质饲料（DCGF）、玉米蛋白粉和血粉的组合（CB），或豆粕和干玉米麸质饲料与CB的组合。估计豆粕、干玉米麸质饲料和CB的瘤胃氮逃逸率分别为32%、25%和68%。补充的粗蛋白来源提供了日粮粗蛋白的35%至40%（12.5%粗蛋白日粮）。在每个时期，将每头阉牛的干物质摄入量调整为体重的2.3%。与其他蛋白质相比，日粮补充尿素时十二指肠的总氮流量降低（P < 0.01），这是由于非微生物氮流量降低（P < 0.01）。然而，尿素组的微生物氮和氨基酸流量比其他蛋白质补充剂组更大（P < 0.05）。随着日粮中CB取代SBM或DCGF，胃中有机物和中性洗涤纤维的消失量降低（P < 0.07）或在数值上更低，但十二指肠中的非微生物氮增加（P < 0.08）。蛋白质来源对瘤胃发酵特性影响较小，只是尿素组的瘤胃氨氮（NH₃N）浓度高于其他处理组（P < 0.05）。随着CB取代DCGF，小肠中总氨基酸和必需氨基酸的流量以及消失量增加（P < 0.06）。然而，用CB替代SBM对肠道氨基酸流量和消失量影响较小。这些数据表明，瘤胃可降解粗蛋白的来源会影响瘤胃可降解和不可降解粗蛋白联合饲喂的效果。一般来说，补充粗蛋白的来源对供应到十二指肠的可吸收氨基酸的数量影响比对其组成的影响更大。
