Chilliard Y, Bocquier F, Doreau M
Laboratoire sous-nutrition des ruminants, France.
Reprod Nutr Dev. 1998 Mar-Apr;38(2):131-52. doi: 10.1051/rnd:19980201.
In response to undernutrition, short- (days) and medium-term (weeks) adaptations are more pronounced for splanchnic organs than for other tissues. For the latter, the long-term response involves a sequential mobilization (fat > muscle > bone) with relative priorities differing among anatomical sites. Among chemical components, the body lipids are extensively used (up to 80%) in underfed animals, while the range of protein utilization is limited (up to 15-20%). The decrease in energy expenditure during undernutrition is mostly due to a short- and medium-term decrease in feeding activity, and in the mass and activity of splanchnic tissues. In the long-term, energy expenditure and tissue masses decrease concomitantly, but there does not appear to be a significant decrease in expenditure per unit tissue weight. Nitrogen losses decrease in response to decline in nitrogen fluxes and also due to sparing by renal activities and sometimes by urea recycling. However, ruminants do not seem to be able to compensate for a low level of intake (below maintenance) by an increase in digestive efficiency. Numerous hormones (insulin, growth hormone, insulin-like growth factor I, catecholamines, thyroid hormones, cortisol, leptin, etc.) are involved in the changes during undernutrition of nutrient fluxes between tissues, either through control of synthesis and/or degradation in peripheral tissues (adipose tissue and muscle), or through hepatic conversions of substrates (gluconeogenesis, ureagenesis and ketogenesis), in order to maintain the constancy of the internal environment (homeostasis) and/or to sustain productive functions (teleophoresis). However, reproductive process may be blocked in underfed animals.
针对营养不足的情况，短期（数天）和中期（数周）的适应性变化在内脏器官中比在其他组织中更为明显。对于后者，长期反应涉及一种顺序性动员（脂肪>肌肉>骨骼），不同解剖部位的相对优先顺序有所不同。在化学成分方面，身体脂肪在营养不良的动物中被大量利用（高达80%），而蛋白质的利用范围有限（高达15 - 20%）。营养不良期间能量消耗的减少主要是由于短期和中期摄食活动的减少，以及内脏组织的质量和活动的减少。从长期来看，能量消耗和组织质量同时下降，但单位组织重量的能量消耗似乎没有显著下降。氮损失随着氮通量的下降而减少，也由于肾脏活动的节省作用，有时还由于尿素再循环。然而，反刍动物似乎无法通过提高消化效率来弥补低水平的摄入量（低于维持量）。许多激素（胰岛素、生长激素、胰岛素样生长因子I、儿茶酚胺、甲状腺激素、皮质醇、瘦素等）参与了营养不良期间组织间营养通量的变化，要么通过控制外周组织（脂肪组织和肌肉）中的合成和/或降解，要么通过肝脏对底物的转化（糖异生、尿素生成和酮体生成），以维持内环境的恒定（稳态）和/或维持生产功能（远距分泌）。然而，营养不良的动物生殖过程可能会受阻。
