Ortigues I, Durand D
Laboratoire Croissance et Métabolismes des Herbivores, INRA, Theix, France.
Br J Nutr. 1995 Feb;73(2):209-26. doi: 10.1079/bjn19950024.
Adaptation of energy metabolism to undernutrition and to the duration of undernutrition was studied in adult, non-pregnant, non-lactating ewes at the whole-animal, portal-drained viscera, liver and hindquarters levels. Arterio-venous and indirect calorimetry techniques were used. Animals were successively fed at 1 times (3 weeks) and at 0.5 times (7 weeks) their metabolizable energy requirements for maintenance (MEm). Portal, hepatic and hindquarters blood flows in quietly standing ewes decreased by 22, 19 and 11% respectively within the first week of undernutrition and remained at that level thereafter. Standardizing hindquarters blood flow to that in a given posture (quietly standing) reduced blood flow by 9.8%. In the portal-drained viscera and liver, O2 extraction rates decreased, leading to 34 and 38% drops in O2 consumption with underfeeding respectively. In the hindquarters, O2 extraction rate increased, partly counterbalancing the drop in blood flow. Thus O2 consumption of hindquarters tended to decrease but the effect was not significant. All changes appeared to be completed from day 5 of underfeeding. Consequently, the portal-drained viscera, liver and carcass were responsible for 39, 32 and 5% respectively of the drop in whole-animal O2 consumption with underfeeding. At the end of the 0.5 x MEm period, in vivo metabolic rates averaged 1.65, 4.89 and 0.38 mmol O2 consumed/d per g fresh weight of adipose-tissue-free portal-drained viscera, liver and boneless hindquarters respectively. Undernutrition imposed a much greater nutritional challenge to splanchnic tissues than to hindquarters. The former reduced their energy expenditure whereas hindquarters metabolism adapted by counteracting the slight drop in nutrient supply.
在成年、非妊娠、非泌乳母羊中，于全动物、门静脉引流内脏、肝脏和后躯水平研究了能量代谢对营养不良及营养不良持续时间的适应性。采用了动静脉和间接测热技术。动物依次按维持代谢能需求（MEm）的1倍（3周）和0.5倍（7周）进食。在营养不良的第一周内，安静站立母羊的门静脉、肝脏和后躯血流量分别下降了22%、19%和11%，此后维持在该水平。将后躯血流量标准化为给定姿势（安静站立）时的血流量，血流量减少了9.8%。在门静脉引流内脏和肝脏中，氧气提取率下降，导致进食不足时氧气消耗量分别下降34%和38%。在后躯中，氧气提取率增加，部分抵消了血流量的下降。因此，后躯的氧气消耗量趋于下降，但影响不显著。所有变化在进食不足的第5天似乎已完成。因此，门静脉引流内脏、肝脏和胴体分别占进食不足时全动物氧气消耗量下降的39%、32%和5%。在0.5×MEm期结束时，无脂肪门静脉引流内脏、肝脏和去骨后躯每克鲜重的体内代谢率平均分别为每天消耗1.65、4.89和0.38 mmol氧气。营养不良对内脏组织造成的营养挑战比对后躯大得多。前者降低了能量消耗，而后躯代谢通过抵消营养供应的轻微下降而适应。
