American Institute for Goat Research, Langston University, Langston, OK 73050, USA.
J Anim Sci. 2011 Dec;89(12):4175-87. doi: 10.2527/jas.2011-3907. Epub 2011 Jul 1.
Sixteen Boer goat doelings, 16 Spanish doelings, and 8 Angora doelings and 8 wethers, 283, 316, and 330 d of age initially (SEM = 5.0), respectively, were used to evaluate effects of nutrient restriction on heat energy (HE). During the first and second 10-wk phases, 8 animals of each breed were fed a 50% concentrate pelletized diet at a level adequate for maintenance and moderate energy accretion (CONT). Other animals were fed approximately 50% of these amounts in phase 1 relative to initial BW, followed by the greater level of feeding in phase 2 based on initial or actual BW when greater (REST). Average daily gain was 43, -20, 16, -78, 8, and -48 g in phase 1 (SEM = 5.0) and 26, 44, 50, 65, 27, and 32 g in phase 2 (SEM = 3.5) for Angora-CONT, Angora-REST, Boer-CONT, Boer-REST, Spanish-CONT, and Spanish-REST, respectively. Total HE was greater for CONT vs. REST in both phases (P < 0.001), greater in phase 1 for Angora than for Boer (P < 0.01) and Spanish (P < 0.01), and greatest (P < 0.01) in phase 2 among breeds for Angora [481, 347, 430, 356, 424, and 338 kJ/kg of BW(0.75) per day in phase 1 (SEM = 11.1), and 494, 479, 445, 397, 444, and 406 kJ/kg of BW(0.75) per day in phase 2 (SEM = 11.3) for Angora-CONT, Angora-REST, Boer-CONT, Boer-REST, Spanish-CONT, and Spanish-REST, respectively]. Equations describing the temporal pattern of HE (kJ/kg of BW(0.75) per day), expressed as a percentage of the wk-0 value and corrected for corresponding breed × week CONT means, in phase 1 were 95.8 ± 2.43 - (8.18 ± 1.144 × week) + (0.655 ± 0.1098 × week(2)) for Angora (R(2) = 0.58), 95.3 ± 2.63 - (4.34 ± 1.237 × wk) + (0.271 ± 0.1187 × wk(2)) for Boer (R(2) = 0.41), and 97.4 ± 2.21 - (4.69 ± 1.068 × wk) + (0.282 ± 0.1021 × wk(2)) for Spanish (R(2) = 0.53). Phase 2 equations were 78.9 ± 2.22 + (8.74 ± 1.036 × wk) - (0.608 ± 0.0095 × wk(2)) for Angora (R(2) = 0.60), 77.5 ± 2.10 + (3.30 ± 0.978 × wk) - (0.153 ± 0.0942 × wk(2)) for Boer (R(2) = 0.39), and 80.6 ± 2.50 + (4.50 ± 1.165 × wk) - (0.208 ± 0.1122 × wk(2)) for Spanish (R(2) = 0.43). These equations indicate that changes in HE in response to nutrient restriction and realimentation were more rapid and of greater magnitude in Angora vs. Boer and Spanish. The temporal pattern of decline in HE by Boer and Spanish during restriction was similar, but the subsequent rise with realimentation was slower and smaller for Boer. In conclusion, most appropriate methods of predicting change in the maintenance energy requirement during and after periods of limited feed intake may differ among breeds of goats.
16 只布尔山羊母羊、16 只西班牙母羊和 8 只安哥拉母羊和 8 只公羊，初始年龄分别为 283、316 和 330 日龄（SEM = 5.0），分别用于评估热能（HE）的营养限制效应。在第一和第二 10 周阶段，每个品种的 8 只动物分别喂食 50%的浓缩颗粒饲料，以维持和适度能量积累的水平（CONT）。在阶段 1 中，相对于初始 BW 喂食这些量的约 50%，在阶段 2 中根据初始或实际 BW 喂食更大的量，当 BW 更大时（REST）。在阶段 1（SEM = 5.0）中，安哥拉-CONT、安哥拉-REST、布尔-CONT、布尔-REST、西班牙-CONT 和西班牙-REST 的平均日增重分别为 43、-20、16、-78、8 和-48 g，在阶段 2（SEM = 3.5）中分别为 26、44、50、65、27 和 32 g。在两个阶段中，CONT 与 REST 相比，总 HE 更高（P < 0.001），在阶段 1 中，安哥拉的 HE 高于布尔（P < 0.01）和西班牙（P < 0.01），在阶段 2 中，安哥拉的 HE 最高（P < 0.01），在阶段 1（SEM = 11.1）中，安哥拉-CONT、安哥拉-REST、布尔-CONT、布尔-REST、西班牙-CONT 和西班牙-REST 的 BW(0.75)的日增重分别为 481、347、430、356、424 和 338 kJ/kg，在阶段 2（SEM = 11.3）中，BW(0.75)的日增重分别为 494、479、445、397、444 和 406 kJ/kg。描述 HE（kJ/kg 的 BW(0.75) 每天）的时间模式的方程，以周 0 值的百分比表示，并校正相应的品种 × 周 CONT 平均值，在阶段 1 中为 95.8 ± 2.43 - (8.18 ± 1.144 × 周) + (0.655 ± 0.1098 × 周 2）对于安哥拉（R(2) = 0.58），95.3 ± 2.63 - (4.34 ± 1.237 × 周) + (0.271 ± 0.1187 × 周 2）对于布尔（R(2) = 0.41），和 97.4 ± 2.21 - (4.69 ± 1.068 × 周) + (0.282 ± 0.1021 × 周 2）对于西班牙（R(2) = 0.53）。阶段 2 方程为 78.9 ± 2.22 + (8.74 ± 1.036 × 周) - (0.608 ± 0.0095 × 周 2）对于安哥拉（R(2) = 0.60），77.5 ± 2.10 + (3.30 ± 0.978 × 周) - (0.153 ± 0.0942 × 周 2）对于布尔（R(2) = 0.39），和 80.6 ± 2.50 + (4.50 ± 1.165 × 周) - (0.208 ± 0.1122 × 周 2）对于西班牙（R(2) = 0.43）。这些方程表明，安哥拉对营养限制和重新饲养的 HE 反应的变化比布尔和西班牙更快，幅度更大。在限制期间，布尔和西班牙 HE 的下降趋势相似，但随后的恢复速度较慢，幅度较小。总之，预测在有限的采食量期间和之后维持能量需求变化的最适当方法可能因山羊品种而异。
