Influence of lasalocid, cationomycin and feeding frequency on the postprandial kinetics of some plasma parameters in the rumen vein, portal vein and mesenteric artery of sheep.

Two adult sheep, A and B, received successively during three experimental periods a forage‐based pelleted feed, then the same diet supplemented with 33 mg/kg of lasalocid (L) or cationomycin (C). The feed was given in either eight (sheep A) or two (sheep B) daily meals. After four weeks of adaptation, 11 blood samples were taken through catheters in the rumen vein (RVA) and the mesenteric artery (MAA) in sheep A and in the rumen vein (RVB) and portal vein (PVB) in sheep B over a 5‐hour period after the morning meal. Because of a blockage in the catheter it was not possible to measure the effect of C in MAA. Food intake had no immediate effect on the plasma levels measured: the distribution of eight daily meals stabilized plasma levels and made it easier to determine the effect of the ionophores. This effect varied according to the sampling site, the animal and the antibiotic, sometimes contradictorily. All the plasma parameters monitored in RVA were significantly modified by either one of the ionophores. ...