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

Tadahisa Fujita,Hiroaki Sano,Takahiro Itoh,Hiroya Majima

doi:10.5713/ajas.2007.365

Abstract

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 []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 (p0.10) with SL or by feeding. Salinomycin decreased (p0.10). A feeding-induced increase in blood acetate concentration was attenuated (p0.10). Plasma concentrations of glucose or insulin were unaffected (p>0.10) with SL. Salinomycin tended to enhance (p0.10). 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.

Highlights

Salinomycin (SL), an ionophore antibiotic, improves feed efficiency and enhances ruminal propionate molar proportion and/or concentration in ruminants fed a highroughage diet (Bagley et al, 1988; Reffett-Stabel et al, 1989; Terashima et al, 1990). These typical effects of SL on ruminal characteristics suggest that dietary SL would enhance whole body glucose kinetics in ruminants, because propionate is the most important precursor for gluconeogenesis and a stimulus for insulin secretion (Bergman, 1990), and glucose production originating from propionate is poorly suppressed with insulin (Brockman, 1990)
Ruminal characteristics careful interpretation of the results on ruminal characteristics is needed because of the very small number of animals used, we chose to include this because we feel it indicates that animals did receive SL and there was an SL response in the rumen
We consider that SL supplementation exerted its typical effects on ruminal metabolism in the present study, since changes in pH, proportions of acetate and propionate and the ratio of acetate to propionate with SL agree with previous results (Bagley et al, 1988; Reffett-Stabel et al, 1989; Terashima et al, 1990)

Summary

Introduction

Salinomycin (SL), an ionophore antibiotic, improves feed efficiency and enhances ruminal propionate molar proportion and/or concentration in ruminants fed a highroughage diet (Bagley et al, 1988; Reffett-Stabel et al, 1989; Terashima et al, 1990). These typical effects of SL on ruminal characteristics suggest that dietary SL would enhance whole body glucose kinetics in ruminants, because propionate is the most important precursor for gluconeogenesis and a stimulus for insulin secretion (Bergman, 1990), and glucose production originating from propionate is poorly suppressed with insulin (Brockman, 1990). SL supplementation may affect glucose kinetics during the early period after feeding in ruminants, because Terashima et al (1990) have shown an enhancement in plasma insulin concentration during the 6 h postfeeding period by SL supplementation in steers fed a high-roughage diet

Methods

Results

Conclusion