Intraruminal propionate supplementation modifies hindlimb energy metabolism without changing the splanchnic release of glucose in growing lambs.
The influence of propionate supplementation on the splanchnic metabolism of energy-yielding nutrients and the supply of glucose to the hindlimb was investigated in growing lambs. Six rumen-cannulated and multicatheterized lambs (32.2 kg), fed frozen rye grass at 690 kJ metabolizable energy intake/d per kg body weight0.75, were infused intraruminally with a salt solution (control) or with propionate solutions at 0.55 mol/d (P1) or 0.98 mol/d (P2) according to a replicated Latin square design. In the rumen fluid, supplementation decreased the acetate:propionate molar ratio from 2.36:1 to 1.37:1, without modifying the ruminal concentrations of acetate and NH4. As a result, the portal appearance of propionate increased by 51 and 72 % with P1 and P2, respectively, and that of l-lactate doubled. Across the liver, net extraction of propionate increased by 47 and 67 % with P1 and P2, respectively. However, the net hepatic production of glucose remained unchanged, probably as the result of a substantial rise in insulin secretion and its hepatic extraction. Overall, the net splanchnic release of acetate, glucose and butyrate was not modified while that of l-lactate increased. Despite this, the net uptake of acetate, glucose, l-lactate and non-esterified fatty acids by the hindlimb increased. Propionate probably enhanced the storage of energy-yielding nutrients in the hindlimb, despite their unchanged release by the splanchnic tissues and the unmodified insulinaemia. Regulatory mechanisms are not clear.
Majdoub
Linda
L
Unité de Recherches sur les Herbivores, INRA Theix, 63122 Saint Genès Champanelle, France.
Vermorel
Michel
M
Ortigues-Marty
Isabelle
I
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet; D019587:Dietary Supplements; D004734:Energy Metabolism / Q000187:drug effects*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006614:Hindlimb / Q000378:metabolism; D007328:Insulin / Q000097:blood; D008099:Liver / Q000378:metabolism; D008297:Male; D011422:Propionates / Q000494:pharmacology*; D012417:Rumen / Q000378:metabolism; D012756:Sheep / Q000378:metabolism*; D013152:Splanchnic Circulation / Q000187:drug effects*
D007328:Insulin; D011422:Propionates; D005947:Glucose