van den Borne Joost J G C, Hocquette Jean-François, Verstegen Martin W A, Gerrits Walter J J
Animal Nutrition Group, Department of Animal Sciences, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands.
Br J Nutr. 2007 Apr;97(4):667-75. doi: 10.1017/S0007114507433098.
The effects of asynchronous availability of amino acids and glucose on muscle composition and enzyme activities in skeletal muscle were studied in preruminant calves. It was hypothesized that decreased oxidative enzyme activities in muscle would explain a decreased whole body heat production with decreasing nutrient synchrony. Preruminant calves were assigned to one of six degrees of nutrient synchrony, step-wise separating the intake of protein and lactose over the two daily meals. Calves at the most synchronous treatment received two identical meals daily. At the most asynchronous treatment, 85% of the daily protein and 20% of the daily lactose supply were fed in one meal and the remainder in the other meal. Daily intakes of all dietary ingredients were identical for all treatments. Oxidative enzyme activities and fat content increased with decreasing nutrient synchrony in M. Rectus Abdominis (RA), but not in M. Semitendinosus. Cytochrome-c-oxidase activity was positively correlated with fat content in RA (r 0.49; P < 0.01). Oxidative enzyme activities in both muscles were not correlated with average daily heat production, but citrate synthase activity in RA was positively correlated (P < 0.01) with the circadian amplitude (r 0.53) and maximum (r 0.61) of heat production associated with physical activity. In conclusion, this study indicates that muscle energy stores are regulated by nutrient synchrony. The lack of correlation between muscle oxidative enzyme activities and average daily heat production was in contrast with findings in human subjects. Therefore, oxidative enzyme activity in muscle should not be used as an indicator for whole body heat production in growing calves.
研究了反刍前犊牛中氨基酸和葡萄糖异步供应对骨骼肌组成和酶活性的影响。研究假设，随着营养同步性降低，肌肉中氧化酶活性降低将解释全身产热的减少。将反刍前犊牛分配到六个营养同步度之一，在两餐中逐步分离蛋白质和乳糖的摄入量。同步性最高的处理组犊牛每天接受两顿相同的餐食。在同步性最低的处理组中，85%的每日蛋白质供应和20%的每日乳糖供应在一餐中喂食，其余在另一餐中喂食。所有处理组的所有膳食成分每日摄入量均相同。腹直肌（RA）中氧化酶活性和脂肪含量随营养同步性降低而增加，但半腱肌中未出现这种情况。细胞色素c氧化酶活性与RA中的脂肪含量呈正相关（r = 0.49；P < 0.01）。两块肌肉中的氧化酶活性与平均每日产热均无相关性，但RA中的柠檬酸合酶活性与身体活动相关的产热的昼夜振幅（r = 0.53）和最大值（r = 0.61）呈正相关（P < 0.01）。总之，本研究表明肌肉能量储备受营养同步性调节。肌肉氧化酶活性与平均每日产热之间缺乏相关性与人类受试者的研究结果相反。因此，肌肉中的氧化酶活性不应作为生长中犊牛全身产热的指标。
