Ebrahimi R, Ahmadi H R, Zamiri M J, Rowghani E
Department of Animal Science, College of Agriculture, Shiraz University, Shiraz, Iran.
Pak J Biol Sci. 2007 May 15;10(10):1679-84. doi: 10.3923/pjbs.2007.1679.1684.
Fifty four Mehraban ram lambs (6-to 8-month old, initial live weight 35.4 +/- 4.2 kg) were assigned to a completely randomized design consisting of 9 groups and were fed for 70 days with diets containing three levels of energy (2.3, 2.5 and 2.7 Mcal metabolizable energy per kg dry matter) and three levels of protein (10.5, 12.5 and 14.5 percentage in dry matter). Either energy or protein levels alone significantly affected most of the parameters of lamb performance, but their interaction effect was significant only for feed conversion ratio, cold carcass weight, tail weight, flap weight and back fat (subcutaneous fat) depth. The lowest level of energy (2.3 Mcal ME per kg DM) resulted in a significant decrease in lamb performance as compared with other energy levels. Increasing energy concentration of the diet resulted in significant increases in fat percentage, but significantly decreased the moisture and protein content of the Longissimus dorsi muscle. Increased dietary protein level increased the daily DMI and ADG and at the same time improved the FCR. Hot and cold carcass weights increased significantly with increasing dietary CP levels, but dressing percentage was similar amongst the dietary protein densities. Dietary CP levels had no significant effect on the chemical composition of the Longissimus dorsi muscle. At the lowest energy level (2.3 Mcal ME per kg DM), dietary protein level had a significant effect on FCR (Table 4); with the diet containing 10.5% protein having the highest FCR. At the medium and low energy levels the lowest level of dietary protein concentration resulted in smaller carcasses. The highest level of protein along with the medium energy concentration resulted in smaller tail weights. Flap weight was significantly smaller at low energy concentration along with medium and low protein level. The lowest back fat depth was found in lambs fed on the low energy diet containing medium to high levels of protein.
54只梅拉班公羊羔羊（6至8月龄，初始活重35.4±4.2千克）被分配到一个完全随机设计中，该设计由9组组成，并饲喂70天，日粮包含三种能量水平（每千克干物质2.3、2.5和2.7兆卡代谢能）和三种蛋白质水平（干物质中分别为10.5%、12.5%和14.5%）。单独的能量或蛋白质水平对羔羊生产性能的大多数参数都有显著影响，但它们的交互作用仅对饲料转化率、冷胴体重、尾重、腹脂重和背膘（皮下脂肪）厚度有显著影响。与其他能量水平相比，最低能量水平（每千克干物质2.3兆卡代谢能）导致羔羊生产性能显著下降。日粮能量浓度的增加导致脂肪百分比显著增加，但显著降低了背最长肌的水分和蛋白质含量。日粮蛋白质水平的提高增加了每日干物质采食量和平均日增重，同时改善了饲料转化率。热胴体重和冷胴体重随日粮粗蛋白水平的增加而显著增加，但屠宰率在不同日粮蛋白质密度之间相似。日粮粗蛋白水平对背最长肌的化学成分没有显著影响。在最低能量水平（每千克干物质2.3兆卡代谢能）下，日粮蛋白质水平对饲料转化率有显著影响（表4）；含10.5%蛋白质的日粮饲料转化率最高。在中低能量水平下，日粮蛋白质浓度最低导致胴体较小。最高蛋白质水平与中等能量浓度相结合导致尾重较小。在低能量浓度以及中低蛋白质水平下，腹脂重显著较小。在饲喂含中高水平蛋白质的低能量日粮的羔羊中发现背膘厚度最低。
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