Carey D A, Caton J S, Biondini M
Department of Animal and Range Sciences, North Dakota State University, Fargo 58105.
J Anim Sci. 1993 Aug;71(8):2260-9. doi: 10.2527/1993.7182260x.
Eight ruminally cannulated steers (average initial weight 196 +/- 13 kg) were arranged in a replicated 4 x 4 Latin square. Steers had ad libitum access to chopped brome hay (Bromus inermus L. 9.9% CP) and one of four supplements. Supplements were fed to provide 195 g of CP.steer-1 x d-1 (equalized with soybean meal), and supplemental energy intake was similar among energy supplements. Supplemental treatments were control (CTRL; primarily soybean meal), barley (BAR), beet pulp (PULP), and corn (CORN). Amounts fed were 481, 1,285, 1,335, and 1,289 g of DM.steer-1 x d-1 for CTRL, BAR, PULP, and CORN, respectively. Individually stanchioned steers were allowed a 13-d adaptation period followed by an 8-d collection period. Chromic oxide was used as the indigestible flow marker. Forage intake was less (P < .10) for steers fed BAR, PULP, and CORN than for CTRL steers, but total intake (forage+supplement) did not differ among treatments. Total tract DM and OM digestibilities were greater (P < .10) for PULP- and CORN- than for CTRL- and BAR-supplemented steers. Digestibility of NDF was least (P < .10) for BAR, intermediate for CORN, and greatest for CTRL and PULP (44.0, 47.2, 50.1, and 52.1%, respectively). Apparent CP digestibility was least (P < .10) in BAR-(60.8), greatest in CTRL- (69.7), and intermediate in PULP- and CTRL- (64.0 and 64.4) supplemented steers. Ruminal DM fill was less (P < .10) in steers fed BAR and PULP than in CTRL steers. No differences (P < .10) were noted in DM and NDF rate of in situ degradation. Rate of forage CP in situ degradation was faster (P < .10) in CTRL- and PULP- than in CORN- and BAR-supplemented steers. Steers fed BAR and PULP supplements exhibited a lower overall pH response curve (P < .005) than did steers fed CTRL and CORN; this finding corresponded to increased (P < .005) response curves in PULP-fed steers for total VFA, acetate, and propionate compared with other treatments. These data indicate that energy supplementation decreased forage intake, altered ruminal fill, shifted VFA patterns, and changed in situ rate of forage CP degradation. Moreover, PULP maintained NDF digestibilities equal to CTRL levels, whereas CORN and BAR did not.
八头装有瘤胃瘘管的阉牛（初始平均体重196±13千克）被安排在一个重复的4×4拉丁方试验中。阉牛可自由采食切碎的无芒雀麦干草（无芒雀麦，粗蛋白含量9.9%）和四种补充料之一。补充料的饲喂量能提供195克粗蛋白/头·天¹（用豆粕平衡），且能量补充料之间的补充能量摄入量相似。补充料处理组分别为对照组（CTRL；主要是豆粕）、大麦（BAR）、甜菜粕（PULP）和玉米（CORN）。CTRL、BAR、PULP和CORN组的干物质饲喂量分别为481、1285、1335和1289克/头·天¹。单独拴系的阉牛有13天的适应期，随后是8天的收集期。氧化铬用作不可消化的流动标记物。饲喂BAR、PULP和CORN的阉牛的牧草摄入量低于（P<0.10）CTRL组阉牛，但各处理组的总摄入量（牧草+补充料）没有差异。PULP组和CORN组阉牛的全消化道干物质和有机物消化率高于（P<0.10）CTRL组和BAR组阉牛。中性洗涤纤维（NDF）的消化率在BAR组最低（P<0.10），CORN组居中，CTRL组和PULP组最高（分别为44.0%、47.2%、50.1%和52.1%）。BAR组阉牛的表观粗蛋白消化率最低（P<0.10）（60.8%），CTRL组最高（69.7%），PULP组和CORN组居中（分别为64.0%和64.4%）。饲喂BAR和PULP的阉牛的瘤胃干物质充盈度低于（P<0.10）CTRL组阉牛。原位降解的干物质和NDF速率没有差异（P<0.10）。CTRL组和PULP组阉牛的牧草粗蛋白原位降解速率快于（P<0.10）CORN组和BAR组阉牛。饲喂BAR和PULP补充料的阉牛比饲喂CTRL和CORN的阉牛表现出更低的总体pH反应曲线（P<0.005）；这一发现与PULP组阉牛相比其他处理组总挥发性脂肪酸（VFA）、乙酸和丙酸的反应曲线增加（P<0.005）相对应。这些数据表明，补充能量会降低牧草摄入量、改变瘤胃充盈度、改变VFA模式并改变牧草粗蛋白的原位降解速率。此外，PULP能使NDF消化率维持在与CTRL组相同的水平，而CORN和BAR则不能。
