Puchala R, Tovar-Luna I, Sahlu T, Freetly H C, Goetsch A L
American Institute for Goat Research, Langston University, Langston, OK, USA.
J Anim Sci. 2009 May;87(5):1714-21. doi: 10.2527/jas.2008-1561. Epub 2009 Feb 11.
Eight Boer (75%) x Spanish (BS) and 8 Spanish (S) wethers (155 +/- 8 d of age and 19.2 +/- 2.3 kg of BW initially) were used in a replicated crossover design with a 2 x 2 factorial arrangement of treatments to determine effects of genotype, diet quality, and time of day on energy expenditure (EE), heart rate (HR), and EE:HR with ad libitum, near maintenance, and fasting levels of feed intake. Diets were 65% concentrate or coarsely ground alfalfa hay. Energy expenditure was ranked (P < 0.05) ad libitum > maintenance > fasting (500, 390, and 270 kJ/kg of metabolic BW). Heart rate did not differ between genotypes when fasting and with maintenance intake, but was greater (P < 0.05) for S than for BS when intake was ad libitum (BS: 55, 71, and 92; S: 52, 72, and 100 beats/min for fasting, maintenance, and ad libitum, respectively, SEM = 2.0). There was an interaction in EE:HR (P < 0.05) between level of feed intake and genotype (BS: 5.31, 5.59, and 5.00; S: 5.07, 5.57, and 5.22 kJ/kg of metabolic BW:beat/min for ad libitum, maintenance, and fasting, respectively, SEM = 0.13), without an effect of diet. The effect of time on EE, HR, and EE:HR differed among levels of intake (P < 0.05). General patterns of change in EE and HR as time of day advanced did not differ, but increases near meals followed by decreases were of slightly greater magnitude for maintenance than for ad libitum intake. The ratio of EE:HR was greater for the maintenance level of feed intake than for ad libitum intake at most times. These results indicate similar potential for use of HR to predict EE of different genotypes of growing meat goats and that establishing EE:HR with different diets or levels of intake may not be crucial. Magnitudes of difference among hours suggest that when EE:HR is used to predict EE of confined goats from full-day measurement of HR, EE:HR should be determined over an extended period of time, such as 24 h.
选用8只波尔山羊（75%）×西班牙山羊（BS）杂交羊和8只西班牙山羊（S）羯羊（初始年龄155±8天，体重19.2±2.3千克），采用重复交叉设计，进行2×2析因处理安排，以确定基因型、日粮质量和采食时间对能量消耗（EE）、心率（HR）以及采食自由、接近维持水平和禁食水平时的EE:HR的影响。日粮为65%精料或粗磨苜蓿干草。能量消耗排序为（P<0.05）采食自由>维持>禁食（每千克代谢体重分别为500、390和270千焦）。禁食和维持采食时，不同基因型的心率无差异，但采食自由时，S基因型的心率高于BS基因型（P<0.05）（禁食、维持和采食自由时，BS分别为55、71和92次/分钟；S分别为52、72和100次/分钟，标准误=2.0）。采食水平和基因型之间在EE:HR上存在交互作用（P<0.05）（采食自由、维持和禁食时，BS每千克代谢体重：次/分钟分别为5.31、5.59和5.00；S分别为5.07、5.57和5.22，标准误=0.13），日粮无影响。采食水平不同，时间对EE、HR和EE:HR的影响也不同（P<0.05）。随着一天时间的推进，EE和HR的总体变化模式无差异，但维持采食时进餐前后的增减幅度略大于采食自由时。大多数时间，维持采食水平时的EE:HR比值高于采食自由时。这些结果表明，利用心率预测生长肉用山羊不同基因型的能量消耗具有相似潜力，并且不同日粮或采食水平下建立EE:HR可能并非关键。各小时之间的差异幅度表明，当用EE:HR根据全天心率测量预测圈养山羊的能量消耗时，应在较长时间段（如24小时）内确定EE:HR。
