Clark J H, Olson K C, Schmidt T B, Linville M L, Alkire D O, Meyer D L, Rentfrow G K, Carr C C, Berg E P
Division of Animal Sciences, University of Missouri-Columbia 920 East Campus Drive, Columbia, MO 65201, USA.
J Anim Sci. 2007 Dec;85(12):3383-90. doi: 10.2527/jas.2006-741. Epub 2007 Sep 4.
Two experiments were conducted to determine the effects of DMI restriction on diet digestion, ruminal fermentation, ME intake, and P retention by beef steers. In Exp. 1, twelve Angus x steers (average initial BW = 450 +/- 18 kg) were assigned randomly to 1 of 3 diets that were formulated to promote a 1.6-kg ADG at intake levels corresponding approximately to 100% (ad libitum, AL), 90% (IR90), or 80% (IR80) of ad libitum DMI. In Exp. 2, twelve crossbred steers (average initial BW = 445 +/- 56 kg) fitted with ruminal cannulae were randomly assigned to 1 of 2 diets that were formulated to promote a 1.6-kg ADG at AL or IR80. All diets delivered similar total NE, MP, Ca, and P per day. During both experiments, fecal DM output by IR80 was less (P </= 0.03) than that of AL; IR90 was similar (P = 0.51) to AL during Exp. 1. Digestion of DM by IR80 cattle was greater (P </= 0.03) than that of AL during both experiments; IR90 was similar (P = 0.31) to AL during Exp. 1. Metabolizable energy intake was similar (P >/= 0.20) among treatments during both experiments, whereas P retention was similar (P >/= 0.46) among treatments during Exp. 1. Total VFA and the molar proportion of acetate of AL were greater (P </= 0.03) than that of IR80 during Exp. 2; however, IR80 had a greater (P = 0.03) molar proportion of propionate. Under the conditions of these studies, restricting DMI while holding NE, ruminally degradable protein, and MP intakes constant decreased fecal DM output and changed ruminal fermentation patterns in finishing steers. Improvements in performance associated with programmed-feeding regimens of the type studied here do not appear to be related to changes in diet digestion or ME intake.
进行了两项试验，以确定限制干物质采食量（DMI）对育肥牛日粮消化、瘤胃发酵、代谢能摄入量和磷保留的影响。在试验1中，12头安格斯杂交阉牛（初始体重平均为450±18千克）被随机分配到3种日粮中的一种，这3种日粮的配制目标是在大约相当于自由采食量（AL）的100%、90%（IR90）或80%（IR80）的采食量水平下实现1.6千克的平均日增重（ADG）。在试验2中，12头装有瘤胃瘘管的杂交阉牛（初始体重平均为445±56千克）被随机分配到2种日粮中的一种，这2种日粮的配制目标是在自由采食或80%自由采食量（IR80）的水平下实现1.6千克的平均日增重。所有日粮每天提供的总净能、代谢蛋白、钙和磷相似。在两项试验期间，80%自由采食量（IR80）组的粪便干物质产量均低于自由采食（AL）组（P≤0.03）；在试验1中，90%自由采食量（IR90）组与自由采食（AL）组相似（P = 0.51）。在两项试验中，80%自由采食量（IR80）组牛的干物质消化率均高于自由采食（AL）组（P≤0.03）；在试验1中，90%自由采食量（IR90）组与自由采食（AL）组相似（P = 0.31）。在两项试验期间，各处理间的代谢能摄入量相似（P≥0.20），而在试验1中，各处理间的磷保留量相似（P≥0.46）。在试验2中，自由采食（AL）组的总挥发性脂肪酸（VFA）和乙酸摩尔比例均高于80%自由采食量（IR80）组（P≤0.03）；然而，80%自由采食量（IR80）组的丙酸摩尔比例更高（P = 0.03）。在本研究条件下，在保持净能、瘤胃可降解蛋白和代谢蛋白摄入量不变的情况下限制干物质采食量，可降低育肥牛的粪便干物质产量，并改变瘤胃发酵模式。本文所研究的这种程序化饲喂方案所带来的生产性能改善，似乎与日粮消化或代谢能摄入量的变化无关。
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