Daura M T, Reid R L
Div. of Anim. and Vet. Sci., West Virginia University, Morgantown 26506.
J Anim Sci. 1991 Jan;69(1):358-68. doi: 10.2527/1991.691358x.
The effect of supplements on intake, digestibility, N retention, ADG and blood and body composition of growing lambs fed cut herbage or grazing KY 31 tall fescue (Festuca arundinacea Schreb.) pastures at two levels of N fertilization (92 and 318 kg/ha) was determined. Supplements were corn (C), corn with soybean meal (U-SBM) and corn with heat-treated SBM (H-SBM). Metabolism trials were run at three growth stages in the 1st yr with 24 lambs. Although all supplements increased total DMI and DM digestibility, they decreased NDF digestibility relative to grass (G), with no difference between supplements; C depressed apparent CP digestibility. Nitrogen retention increased from -2.5 g/d on G to -.4 g/d on C and 3.2 and 4.1 g/d on U-SBM and H-SBM, respectively, for combined periods and N rates. Blood urea N (BUN) concentrations differed (P less than .01) in the following order: G greater than U-SBM greater than H-SBM greater than C. In the 2nd yr, lambs (n = 64) grazed fescue pastures at the same N fertilizer rates and were given the same supplements. Gains were not different (P less than .05) on low-N (LN) and high-N (HN) pastures. Seasonal ADG were 80, 115, 122 and 130 g/d for G, C, U-SBM and H-SBM treatments, respectively, with no difference (P less than .05) between U-SBM and H-SBM. At slaughter, lambs from G had lower dressing percentages (P less than .05) and fat content (P less than .01) than lambs on C, U-SBM and H-SBM treatments, with no differences between supplements. Results indicated a better performance of growing lambs on fescue with both energy and protein supplements. Response to protected vs unprotected protein was small.
测定了在两种施氮水平（92和318千克/公顷）下，给采食切碎牧草或放牧肯塔基31高羊茅（Festuca arundinacea Schreb.）草地的生长羔羊补饲玉米（C）、玉米加豆粕（U-SBM）和玉米加热处理豆粕（H-SBM）对其采食量、消化率、氮保留、平均日增重以及血液和身体组成的影响。在第1年的三个生长阶段，用24只羔羊进行了代谢试验。虽然所有补饲都提高了总干物质采食量和干物质消化率，但相对于牧草（G），它们降低了中性洗涤纤维消化率，补饲之间没有差异；C降低了表观粗蛋白消化率。综合各阶段和氮水平，氮保留量从采食牧草时的-2.5克/天增加到采食C时的-0.4克/天，采食U-SBM和H-SBM时分别为3.2克/天和4.1克/天。血尿素氮（BUN）浓度差异显著（P<0.01），顺序如下：G>U-SBM>H-SBM>C。在第2年，64只羔羊以相同的施氮量放牧羊茅草地，并给予相同的补饲。低氮（LN）和高氮（HN）草地的增重没有差异（P<0.05）。G、C、U-SBM和H-SBM处理的季节性平均日增重分别为80、115、122和130克/天，U-SBM和H-SBM之间没有差异（P<0.05）。屠宰时，采食G的羔羊的屠宰率（P<0.05）和脂肪含量（P<0.01）低于采食C、U-SBM和H-SBM处理的羔羊，补饲之间没有差异。结果表明，给生长羔羊补饲能量和蛋白质时，在羊茅草地上的生产性能更好。对保护性蛋白和非保护性蛋白的反应较小。
