Bodine T N, Purvis H T, Lalman D L
Department of Animal Science, Oklahoma Agricultural Experiment Station, Stillwater 74078-6051, USA.
J Anim Sci. 2001 Apr;79(4):1041-51. doi: 10.2527/2001.7941041x.
Two experiments were conducted to determine the effects of supplement type on the rate of gain by heifers grazing bermudagrass and on the intake, apparent total-tract OM digestibility, ruminal fermentation, digesta kinetics, in situ DM digestibility, and forage protein degradation by steers fed prairie hay. In Exp. 1, 45 heifers (284+/-24 kg) grazed a bermudagrass pasture for 91 d in the late summer to determine the effects of no supplement (CON), or one of four individually fed monensin-containing (150 mg/[heifer x d]) supplements (MINCS; 0.1 kg of mineral mix with 0.2 kg [DM] of cottonseed hulls as a carrier/[heifer x d]), a pelleted protein supplement (PROT; 1 kg of DM, 242 g of degradable intake protein [DIP]/[heifer x d]), or high-fiber (HF) and high-grain (HG) (2 kg of DM, 243 and 257 g of DIP, respectively/[heifer x d]) pelleted energy supplements. In Exp. 2, four ruminally cannulated steers (311+/-22 kg) with ad libitum access to low-quality (4% DIP, 73% NDF, 40% ADF) prairie hay were individually fed monensin-containing (200 mg/[steer x d]) treatments consisting of 1) mineral mix + corn (MINCR; 0.1 kg of mineral and 0.4 kg of cracked corn [DM] as a carrier, 19 g of DIP/[steer x d]), 2) PROT (1.4 kg of DM, 335 g of DIP/[steer x d]), 3) HF, or 4) HG (2.9 kg of DM, 340 and 360 g of DIP, respectively/[steer x d]) in a 4 x 4 Latin square with 14-d adaptation and 6-d sampling periods. In Exp. 1, the HF-, HG-, and PROT-supplemented heifers had greater (P < 0.01) rates of gain than CON heifers, and the HF- and HG-supplemented heifers tended (P < 0.11) to gain more weight than those fed PROT. In Exp. 2, steers fed PROT consumed more (P < 0.05) hay OM than HF and HG, or MINCR. Total OM intake was greater (P < 0.01) by supplemented steers than MINCR-fed cattle. Hay OM digestibility was not affected (P = 0.19) by treatment, but total diet OM digestibility was greater (P < 0.01) for HF- and HG- than for MINCR- or PROT-fed steers. The rate of in situ DM digestibility was greater (P < 0.01) for HF, HG, and PROT than for MINCR. Results from these studies indicate that feeding milo- vs fiber-based energy supplements formulated to provide adequate DIP did not result in different forage intake, OM digestibility, or in situ DM digestibility, whereas both increased ADG in heifers consuming low-quality forages compared with unsupplemented or mineral- or protein-supplemented cattle. An adequate DIP:TDN balance decreased the negative associative effects often observed when large quantities of high-starch supplements are fed with low-quality hay.
进行了两项试验，以确定补充料类型对放牧百慕大草的小母牛增重率，以及对采食低质（4% 可降解摄入蛋白、73% 中性洗涤纤维、40% 酸性洗涤纤维）草原干草的阉牛的采食量、表观全消化道有机物消化率、瘤胃发酵、食糜动力学、原位干物质消化率和饲草蛋白质降解的影响。在试验1中，45头小母牛（284±24千克）于夏末在百慕大草场上放牧91天，以确定不补充（对照）、或四种单独饲喂含莫能菌素（150毫克/[小母牛×天]）补充料之一（MINCS；0.1千克矿物质混合料与0.2千克[干物质]棉籽壳作为载体/[小母牛×天]）、一种颗粒蛋白补充料（PROT；1千克干物质，242克可降解摄入蛋白[DIP]/[小母牛×天]）或者高纤维（HF）和高谷物（HG）（分别为2千克干物质，243和257克DIP/[小母牛×天]）颗粒能量补充料的效果。在试验2中，四头安装了瘤胃瘘管的阉牛（311±22千克）可随意采食低质草原干草，它们被单独饲喂含莫能菌素（200毫克/[阉牛×天]）的处理，处理包括：1）矿物质混合料 + 玉米（MINCR；0.1千克矿物质和0.4千克破碎玉米[干物质]作为载体，19克DIP/[阉牛×天]），2）PROT（1.4千克干物质，335克DIP/[阉牛×天]），3）HF，或4）HG（2.9千克干物质，分别为340和360克DIP/[阉牛×天]），采用4×4拉丁方设计，适应期14天，采样期6天。在试验1中，补充HF、HG和PROT的小母牛比对照小母牛有更高（P<0.01）的增重率，并且补充HF和HG的小母牛比饲喂PROT的小母牛倾向于（P<0.11）增重更多。在试验2中，饲喂PROT的阉牛比HF、HG或MINCR采食更多（P<0.05）的干草有机物。补充阉牛的总有机物采食量比饲喂MINCR的牛更高（P<0.01）。处理对干草有机物消化率没有影响（P = 0.19），但是HF和HG组阉牛的全日粮有机物消化率比MINCR或PROT组更高（P<0.01）。HF、HG和PROT组的原位干物质消化率比MINCR组更高（P<0.01）。这些研究结果表明，饲喂为提供充足DIP而配制的基于高粱与基于纤维的能量补充料，并未导致不同的饲草采食量、有机物消化率或原位干物质消化率，然而与未补充、或补充矿物质或蛋白质的牛相比，二者均提高了采食低质饲草的小母牛的平均日增重。充足的DIP:TDN平衡降低了大量高淀粉补充料与低质干草一起饲喂时经常观察到的负协同效应。
