Influence of Dietary Salinomycin on Feeding-induced Variations of Glucose Kinetics and Blood Volatile Fatty Acids and Insulin Concentrations in Sheep Fed a High-roughage Diet

This study was conducted to determine effects of salinomycin (SL) on feeding-induced changes in glucose kinetics and blood VFA concentrations in sheep fed a high-roughage diet. Four sheep were fed the diet with or without 20 mg/kg diet of SL once daily for 21 d. Glucose entry and utilization rates were determined during the prefeeding and 3 h postfeeding periods, using a [$^{13}C_6$]glucose dilution method and non-steady state equations. Ruminal characteristics and concentrations of blood VFA, plasma glucose and insulin were also measured during the same periods. A feeding-induced increase in ruminal total VFA concentration tended to be inhibited (p<0.10) with SL, although ruminal pH was unaffected (p>0.10) with SL or by feeding. Salinomycin decreased (p<0.05) acetate proportion and increased (p<0.05) propionate proportion in the rumen, but did not modify these changes in response to feeding (p>0.10). A feeding-induced increase in blood acetate concentration was attenuated (p<0.05) with SL. Salinomycin tended to increase (p<0.10) blood propionate concentration without modifying its response patterns to feeding (p>0.10). Plasma concentrations of glucose or insulin were unaffected (p>0.10) with SL. Salinomycin tended to enhance (p<0.10) glucose entry and utilization rates. Feeding also enhanced (p<0.01) both rates, whereas their interactive effect was not detected (p>0.10). We conclude that SL possibly enhances whole body glucose entry and utilization with an increase in blood propionate concentration in sheep given a high-roughage diet, although SL does not appear to affect their responses to feeding.