Arieli A, Schrama J W, Van der Hel W, Verstegen M W
Department of Animal Science, Faculty of Agriculture, Rehovot, Israel.
J Dairy Sci. 1995 May;78(5):1154-62. doi: 10.3168/jds.S0022-0302(95)76732-7.
Modifications in thermal demand and energy partitioning in newborn calves were determined over time via indirect calorimetry. One-week-old calves were fed milk replacer at 70 and 110% of the metabolizable energy requirements for maintenance, at ambient temperatures of 7.5 or 19 degrees C, over two consecutive but separately monitored 7-d balance periods. During wk 1, N digestibility, energy digestibility, and energy metabolizability were lower than during wk 2. Heat production decreased, but retention of energy and fat increased, between balance periods. During wk 1, initial IgG concentration in serum was positively correlated with digestibilities of N and energy, and hemoglobin concentration was negatively correlated with heat production. Regression analysis revealed that predicted basal metabolic rate, efficiency of metabolizable energy use, and metabolizable energy requirements for maintenance were lower for wk 2 than for wk 1. Decreased energy utilization in calves on restricted feedings is related to an increase in the utilization of protein as an energy source. Young calves need at least 2 wk to adapt to the combination of new environmental temperature and low feeding amount. Metabolic partitioning of energy may indicate completion of the adaptation stage.
通过间接量热法测定新生犊牛热需求和能量分配随时间的变化。在7.5或19摄氏度的环境温度下，对一周龄犊牛连续进行两个分别监测的7天平衡期试验，以维持代谢能需求的70%和110%的量饲喂代乳粉。在第1周，氮消化率、能量消化率和能量代谢率低于第2周。在平衡期之间，产热减少，但能量和脂肪的保留增加。在第1周，血清中初始免疫球蛋白G浓度与氮和能量的消化率呈正相关，血红蛋白浓度与产热呈负相关。回归分析显示，第2周预测的基础代谢率、代谢能利用效率和维持代谢能需求均低于第1周。限饲犊牛能量利用的降低与蛋白质作为能量来源利用的增加有关。幼龄犊牛至少需要2周时间来适应新环境温度和低饲喂量的组合。能量的代谢分配可能表明适应阶段的完成。
