Faverdin P
INRA, Station de recherche sur la vache laitière, Saint-Gilles, France.
Proc Nutr Soc. 1999 Aug;58(3):523-31. doi: 10.1017/s0029665199000695.
The purpose of the present review is to examine the role played by nutrients in controlling feed intake in ruminants, in light of their particular anatomical, physiological, nutritional and behavioural characteristics. The ration is first digested in the rumen for several hours by microbial fermentation. Volatile fatty acids, which constitute 50-75% of a ruminant's energy supply, considerably depress feed intake when administered by short-term infusion into the rumen. However, this effect seems to be largely due to osmolarity problems. Only propionate seems to have a specific action, unrelated to osmolarity, in the mesenteric or portal veins. Nitrogenous nutrients have little short-term effect on feed intake, except when there is excess NH3 in the rumen. Metabolic cues from intestinal digestion, particularly of glucose and starch, have very little short- or long-term influence in controlling feed intake, in comparison with rumen digestion cues. However, the short-term responses in feeding behaviour do not always reflect longer-term effects on feed intake control. The effects of volatile fatty acid infusion on feed intake are much less significant over the long term, except in the case of propionate. The nutrients required for good microbial activity (proteins in the rumen) generally promote feed intake, whereas nutrients that disrupt rumen functioning (lipids) reduce feed intake. After a learning period, preferences are always governed by a tendency toward optimum rumen functioning, rather than by animal nutritional requirements, although the two factors are not independent. Ruminants, due to their particular anatomical and nutritional characteristics, have, in the course of their evolution, developed specific feed intake control mechanisms based on nutritional cues.
本综述的目的是根据反刍动物特殊的解剖学、生理学、营养和行为特征，研究营养物质在控制反刍动物采食量方面所起的作用。日粮首先在瘤胃中通过微生物发酵消化数小时。挥发性脂肪酸占反刍动物能量供应的50%-75%，当通过短期注入瘤胃给予时，会显著抑制采食量。然而，这种影响似乎很大程度上是由于渗透压问题。只有丙酸似乎在肠系膜或门静脉中具有与渗透压无关的特定作用。含氮营养物质对采食量的短期影响很小，除非瘤胃中存在过量的NH3。与瘤胃消化信号相比，肠道消化产生的代谢信号，特别是葡萄糖和淀粉的代谢信号，在控制采食量方面几乎没有短期或长期影响。然而，采食行为的短期反应并不总是反映对采食量控制的长期影响。除丙酸外，挥发性脂肪酸注入对采食量的长期影响要小得多。良好微生物活性所需的营养物质（瘤胃中的蛋白质）通常会促进采食量，而破坏瘤胃功能的营养物质（脂质）则会降低采食量。经过一个学习期后，偏好总是由瘤胃功能达到最佳的趋势决定，而不是由动物的营养需求决定，尽管这两个因素并非相互独立。由于其特殊的解剖学和营养特征，反刍动物在进化过程中基于营养信号发展出了特定的采食量控制机制。
