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La cétogenèse chez le ruminant à jeun : influence des acides gras volatils, du glucose et de l'alanine

1977; Elsevier BV; Volume: 17; Issue: 5B Linguagem: Inglês

10.1051/rnd

1297-9708

Christian Demigné, Christian Rémésy,

Ruminant Nutrition and Digestive Physiology

Ketogenesis in the fasting ruminant.Effect of volatile fatty acids, glucose and alanine.Lambs weighing about 30 kg were fasted 48 or 78 h to study the effect of volatile fatty acids (AGV) and glucogenic substrates on ketogenesis.The AGV were administered intra- ruminaly and the glucose and alanine in L or DL form subcutaneously.Excess acetate had an antilipolytic effect accompanied by a slight rise in ketone bodies, while excess butyrate was antilipolytic and ketogenic.The propionate was very antiketogenic for free fatty acids or for butyrate.L-alanine had little effect, whereas its antiketogenic action was strong but brief ; this effect did not seem due solely to hyper- glycemia.DL-alanine had effectssimilarto L-alanine, but they occurred later.The mechanisms of liver ketogenesis regulation are discussed in relation to acyl CoA transport to the mitochondria or to the orientation of acetyl CoA metabolism towards lipogenesis rather than towards ketogenesis ; particular attention is given to butyrate.