Bodine T N, Purvis H T, Ackerman C J, Goad C L
Department of Animal Science, Oklahoma Agricultural Experiment Station, Stillwater 74078-6051, USA.
J Anim Sci. 2000 Dec;78(12):3144-54. doi: 10.2527/2000.78123144x.
Prairie hay supplemented with various amounts of corn and soybean meal was fed to steers in two experiments. Effects of supplementation on hay OM intake, digestion, and ruminal fermentation and kinetics were measured. A preliminary study was conducted to attain accurate values for OM intake and digestibility of prairie hay to be used in ration formulation using the NRC (1996) level 1 model. Ten steers (284 +/- 9 kg) given ad libitum access to chopped prairie hay (75% NDF, 6% CP) were supplemented with dry-rolled corn (0.75% of BW/d) plus soybean meal (0.25% of BW/d). Hay OM intake was 1.85% of BW and hay OM digestibility was 48%. Based on results from the preliminary study, eight ruminally cannulated beef steers (317 +/- 25 kg) received a sequence of eight different supplementation combinations (2 x 4 factorial arrangement of treatments). These supplements consisted of dry-rolled corn at either 0 or 0.75% of BW (DM basis) daily combined with one of four amounts of added soybean meal to provide between 0 and 1.3 g of degradable intake protein (DIP)/kg of BW. After supplements had been fed for 10 d, feces were collected for 4 d. Intake of hay and total OM increased quadratically (P < 0.01) in response to added DIP with or without supplemental corn. Hay OM digestibility increased quadratically (P = 0.03) as DIP was added when corn was fed in the supplement. Intake of digestible OM was greater (P < 0.01) with than without corn supplementation. Increasing DIP increased (P < 0.01) digestible OM intake regardless of whether corn was fed. Inadequate ruminally degraded protein in grain-based supplements decreased forage intake, digestibility, and energy intake of cattle fed low-quality prairie hay. Providing adequate supplemental DIP to meet total diet DIP needs seemed to overcome negative associative effects typically found from supplementing low-quality forages with large quantities of low-protein, high-starch feeds.
在两项试验中，给肉牛饲喂添加了不同量玉米和豆粕的苜蓿干草。测定了添加物对干草有机物质采食量、消化率、瘤胃发酵及动力学的影响。进行了一项初步研究，以获取用于使用NRC（1996）一级模型进行日粮配方的苜蓿干草有机物质采食量和消化率的准确值。给10头肉牛（体重284±9千克）自由采食切碎的苜蓿干草（中性洗涤纤维含量75%，粗蛋白含量6%），并添加干压玉米（占体重的0.75%/天）和豆粕（占体重的0.25%/天）。干草有机物质采食量为体重的1.85%，干草有机物质消化率为48%。根据初步研究结果，8头装有瘤胃瘘管的肉牛（体重317±25千克）接受了8种不同添加组合（2×4析因处理安排）。这些添加物包括每天按体重0或0.75%（干物质基础）的干压玉米，再加上四种添加量的豆粕之一，以提供每千克体重0至1.3克的可降解摄入蛋白（DIP）。添加物饲喂10天后，收集粪便4天。无论是否添加玉米，随着DIP的添加，干草和总有机物质的采食量呈二次曲线增加（P<0.01）。当添加物中添加玉米时，随着DIP的添加，干草有机物质消化率呈二次曲线增加（P = 0.03）。添加玉米时可消化有机物质的采食量高于不添加玉米时（P<0.01）。无论是否添加玉米，增加DIP均可提高（P<0.01）可消化有机物质的采食量。以谷物为基础的添加物中瘤胃降解蛋白不足会降低采食低质量苜蓿干草的肉牛的采食量、消化率和能量摄入量。提供足够的补充DIP以满足总日粮DIP需求似乎可以克服通常在使用大量低蛋白、高淀粉饲料补充低质量粗饲料时发现的负组合效应。
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