American Institute for Goat Research, Langston University, Langston, OK 73050, USA.
J Anim Sci. 2011 Jan;89(1):142-9. doi: 10.2527/jas.2010-3054. Epub 2010 Oct 1.
Twelve mature Angora does were used in a replicated 3 × 3 Latin square to determine effects of feeding level on energy utilization. Fiber growth and change in tissue (nonfiber) mass were determined in the first 4 wk of 6-wk periods, preceded by 14 or 18 d of adaptation. Determination of ME intake and gas exchange measures occurred in wk 4, followed by feeding near maintenance, then fasting in wk 5 and 6 to determine the ME requirement for maintenance (ME(m)). A 60% concentrate diet was fed at levels to approximate 100, 125, and 150% of assumed ME(m) [low, medium (med), and high, respectively]. Digestibilities and diet ME/GE were not affected by treatment with different amounts of feed offered and subsequent intake near ME(m). Heat energy during fasting (261, 241, and 259 kJ/kg of BW(0.75); SEM = 8.7) and efficiency of ME used for maintenance (71.6, 69.6, and 69.2%; SEM = 2.29) were similar among treatments, although ME(m) differed (P < 0.04) between med and high (365, 344, and 377 kJ/kg of BW(0.75) for low, med, and high, respectively; SEM = 10.3). Tissue gain was less (P < 0.01) for low than for the mean of med and high (MH; -0.6, 23.7, and 29.8 g/d), although clean fiber growth only tended (P < 0.09) to differ between low and MH (5.60, 6.57, and 7.36 g/d for low, med, and high, respectively; SEM = 0.621). Intake of ME was greater (P < 0.01) for MH than for low (6.87, 8.22, and 8.41 MJ/d for low, med, and high, respectively). Total heat energy was less (P < 0.02) for low vs. MH and tended (P < 0.07) to be greater for high than for med (6.03, 6.31, and 6.77 MJ/d); mobilized tissue energy was low but greater (P < 0.02) for low vs. MH (0.16, 0.01, and 0.04 MJ/d for low, med, and high, respectively). Efficiency of ME use for fiber growth was similar among treatments (17.2, 16.3, and 17.7% for low, med, and high, respectively; SEM = 1.61). In conclusion, efficiency of ME use for fiber growth was similar to the NRC recommendation regardless of feeding level, although ME(m) was decreased perhaps because of experimental conditions used. Energy appeared partitioned to fiber growth, but preferential usage was not complete possibly because energy metabolism for tissue accretion reached a plateau with the greatest feeding level.
十二只成熟的安哥拉兔被用于复制的 3×3 拉丁方试验，以确定饲养水平对能量利用的影响。在 6 周的前 4 周内测定纤维生长和组织（非纤维）质量的变化，之前有 14 或 18 天的适应期。在第 4 周测定代谢能摄入量和气体交换测量值，然后在第 5 和第 6 周接近维持饲养，然后禁食，以确定维持的代谢能需求（ME(m)）。用接近 100%、125%和 150%假设 ME(m)（低、中、高，分别）的水平饲喂 60%浓缩饲料。用不同量的饲料处理和随后接近 ME(m)的摄入，不会影响消化率和饲料 ME/GE。禁食期间的热能（261、241 和 259 kJ/kg BW(0.75)；SEM=8.7）和用于维持的 ME 效率（71.6、69.6 和 69.2%；SEM=2.29）在处理之间相似，尽管 ME(m)在中（med）和高（high）之间存在差异（P＜0.04）（低、中、高分别为 365、344 和 377 kJ/kg BW(0.75)；SEM=10.3）。低处理组的组织生长较少（P＜0.01），低于中（MH）的平均值（-0.6、23.7 和 29.8 g/d），尽管清洁纤维生长仅倾向于（P＜0.09）在低和 MH 之间存在差异（5.60、6.57 和 7.36 g/d 分别为低、中、高；SEM=0.621）。中（MH）的 ME 摄入量高于低（P＜0.01）（低、中、高分别为 6.87、8.22 和 8.41 MJ/d）。总热能较低（P＜0.02），MH 比低，高（P＜0.07）比中更倾向于高（6.03、6.31 和 6.77 MJ/d）；动员组织能量较低，但低（P＜0.02）比 MH 高（0.16、0.01 和 0.04 MJ/d 分别为低、中、高）。纤维生长的 ME 利用效率在处理之间相似（低、中、高分别为 17.2、16.3 和 17.7%；SEM=1.61）。总之，无论饲养水平如何，纤维生长的 ME 利用效率与 NRC 建议相似，尽管 ME(m)可能因使用的实验条件而降低。能量似乎分配给了纤维生长，但优先使用并不完全，可能是因为组织蓄积的能量代谢达到了一个平台，而最高的饲养水平。
