Sano H, Terashima Y
Faculty of Animal Science, Kitasoto University, Towada, Japan.
J Anim Physiol Anim Nutr (Berl). 2001 Dec;85(11-12):349-55. doi: 10.1046/j.1439-0396.2001.00345.x.
The effects of dietary crude protein (CP) level and cold exposure on tissue responsiveness and sensitivity to insulin were studied in sheep. Nine rams were assigned to one of three isoenergetic diets which contained 70, 100, and 140% of CP for maintenance. They were exposed from a thermoneutral environment (20 degrees C) to a cold environment (0 degrees C) for 7 days. A hyperinsulinemic euglycemic clamp approach was applied for the determination of tissue responsiveness to insulin (the maximal glucose infusion rate, GIRmax) and tissue sensitivity to insulin (the plasma insulin concentration at half maximal glucose infusion rate, ED50). Dietary CP level influenced digestibilities of dry matter and CP (P=0.002 and P=0.001, respectively), and cold exposure decreased (P=0.01) CP digestibility. The GIRmax and ED50 tended to be influenced (P=0.08) by dietary CP level. The GIRmax was enhanced (P=0.0001) during cold exposure. Significant interactions between diet and environment were found for the GIRmax (P=0.04), but not for ED50 (P=0.07). It is concluded that in sheep dietary CP level can modify insulin action in response to cold exposure.
研究了日粮粗蛋白（CP）水平和冷暴露对绵羊组织对胰岛素的反应性和敏感性的影响。将9只公羊分配到三种等能量日粮中的一种，这些日粮分别含有维持所需CP的70%、100%和140%。它们从热中性环境（20℃）暴露于寒冷环境（0℃）7天。采用高胰岛素正常血糖钳夹法测定组织对胰岛素的反应性（最大葡萄糖输注速率，GIRmax）和组织对胰岛素的敏感性（达到最大葡萄糖输注速率一半时的血浆胰岛素浓度，ED50）。日粮CP水平影响干物质和CP的消化率（分别为P = 0.002和P = 0.001），冷暴露降低了CP消化率（P = 0.01）。GIRmax和ED50有受日粮CP水平影响的趋势（P = 0.08）。冷暴露期间GIRmax升高（P = 0.0001）。发现日粮和环境之间对GIRmax存在显著交互作用（P = 0.04），但对ED50不存在（P = 0.07）。得出结论，在绵羊中，日粮CP水平可改变冷暴露时的胰岛素作用。
