Brosh A, Henkin Z, Ungar E D, Dolev A, Orlov A, Yehuda Y, Aharoni Y
Beef Cattle Section, ARO, Newe Yaar Research Center, P.O. Box 1021 Ramat Yishay 30095, Israel.
J Anim Sci. 2006 Jul;84(7):1951-67. doi: 10.2527/jas.2005-315.
This study with grazing beef cows on the range was designed to explore the possibility of determining incremental energy expenditure (EE) in standing, traveling, and grazing relative to that in lying down, by means of continuous monitoring of EE, location, and activity by the heart-rate method, with Global Positioning System (GPS) collars, and by motion sensors in the GPS collars, respectively. Cows were observed on Mediterranean foothill rangeland covered with herbaceous vegetation through 4 seasons of the year. There were 2 stocking rate treatments, and 14 statistical models were evaluated, including one that was a stepwise model. Total daily EE (TEE) was affected by many interdependent factors apart from activity, including season, stocking rate, herbage quality, standing biomass, and reproductive state of the cow. Each model included all activity variables, plus some of the other factors. Across seasons and treatments TEE, in kJ/(kg of BW(0.75) . d), ranged from 469 in densely stocked, nonlactating cows in June to 1,092 in sparsely stocked, lactating cows in April. The cows' daily vertical and horizontal movements ranged from 75 to 174 m and from 1.5 to 4.2 km, respectively. Within a day, time spent traveling (without grazing) ranged from 0 to 32 min, and grazing time ranged from 4.4 to 12.1 h. Cows spent less time grazing (P < 0.001) in the summer, when herbage quality was low, than in winter and spring. Relative to the baseline EE while lying down, the daily increment incurred by grazing ranged from 13 to 48 kJ/(kg of BW(0.75) . d), and that incurred by grazing, standing, and traveling combined ranged from 38 to 74 kJ/(kg of BW(0.75) . d) or 5.8 to 11.4% of TEE. In conclusion, the estimates of activity costs yielded by 11 of the models were similar to one another, whereas those yielded by the stepwise model and the remaining 2 models were 20% smaller. The cost of grazing activity was estimated to be 6.14 J/(kg of BW(0.75) . m), and that of locomotion during grazing was 6.07 J/(kg of BW(0.75) . m), which agree with values obtained for animals and humans by means of a treadmill. The experimental and statistical approach tested here yielded fairly reliable estimations of energy costs of activities in grazing cows.
本研究以放牧于牧场上的肉牛为对象，旨在通过心率法、全球定位系统（GPS）项圈以及GPS项圈中的运动传感器分别持续监测能量消耗（EE）、位置和活动，探索确定站立、行走和放牧相对于躺卧时的增量能量消耗的可能性。在一年的4个季节里，对覆盖着草本植被的地中海山麓牧场的奶牛进行了观察。设置了2种载畜率处理，并评估了14种统计模型，其中包括一种逐步模型。除活动外，总日能量消耗（TEE）还受许多相互依存的因素影响，包括季节、载畜率、牧草质量、站立生物量和奶牛的繁殖状态。每个模型都包括所有活动变量以及一些其他因素。在不同季节和处理条件下，以kJ/（kg体重（0.75）·天）为单位的TEE范围为：6月密集饲养的非泌乳奶牛为469，4月稀疏饲养的泌乳奶牛为1092。奶牛每天的垂直和水平移动距离分别为75至174米和1.5至4.2千米。在一天内，行走（不包括放牧）时间为0至32分钟，放牧时间为4.4至12.1小时。在夏季牧草质量较低时，奶牛的放牧时间比冬季和春季少（P < 0.001）。相对于躺卧时的基础EE，放牧引起的每日增量为13至48 kJ/（kg体重（0.75）·天），放牧、站立和行走共同引起的增量为38至74 kJ/（kg体重（0.75）·天），占TEE的5.8%至11.4%。总之，11种模型得出的活动成本估计值彼此相似，而逐步模型和其余2种模型得出的估计值则小20%。放牧活动的成本估计为6.14 J/（kg体重（0.75）·米），放牧期间的运动成本为6.07 J/（kg体重（0.75）·米），这与通过跑步机对动物和人类得出的值一致。此处测试的实验和统计方法对放牧奶牛活动的能量成本得出了相当可靠的估计。
