Department of Animal Science, North Carolina State University, Raleigh, NC.
Kemin AgriFoods North America, Inc., Des Moines, IA.
J Anim Sci. 2020 Apr 1;98(4). doi: 10.1093/jas/skaa095.
Forty-eight Quarter Horse geldings (3 to 8 yr of age) were used to determine the effects of dietary chromium (Cr), in the form of Cr propionate (Cr Prop) on insulin sensitivity. Horses were blocked by age, body condition score, and glucose response to concentrate feeding on day 0 and randomly assigned to treatments. Treatments consisted of 0, 2, 4, or 8 mg Cr/d from Cr Prop. Horses were fed daily a concentrate mix at a rate of 0.2 kg/100 kg body weight (BW) and grass hay at 1.75 to 2.0 kg/100 kg BW. All horses were fed the control diet for 7 d prior to the initiation of the study. After an overnight fast, blood samples from the jugular vein were obtained at 0, 2, and 4 h after concentrate feeding on days 0 and 28 for the determination of glucose, nonesterified fatty acids, and insulin. A glucose tolerance test (GTT) was conducted on day 42. Glucose was infused via jugular vein catheters, and blood samples were collected at various times relative to dosing for glucose and insulin determination. Plasma glucose on day 28 was affected (P < 0.05) by treatment, time, and treatment × time. Horses fed 4 mg Cr/d had lesser (P < 0.05) plasma glucose concentrations than those in the other treatments at 0 h. At 2 h post-feeding glucose concentrations were greater (P < 0.05) in horses fed 0 or 8 mg Cr/d than in those given 4 mg Cr. Horses fed 2 mg Cr/d had lesser (P < 0.05) plasma glucose at 4 h post feeding compared with those fed 0 or 8 mg Cr. Plasma glucose did not differ among horses receiving 2 or 4 mg Cr/d at 2 or 4 h. Serum insulin was affected (P < 0.05) by treatment, time, and treatment × time. Insulin concentrations were greater (P < 0.05) in horses fed 0 or 2 mg Cr/d than in those given 4 or 8 mg Cr at 0 h. At 4 h post-feeding insulin concentrations were greater (P < 0.05) in horses given 0 or 8 mg Cr than in those fed 2 or 4 mg Cr/d. Plasma glucose was affected (P < 0.05) by treatment and time, but not by treatment × time following the GTT. Mean plasma glucose (across sampling times) concentrations were greater (P < 0.05) in controls than in horses fed 2 or 4 mg Cr/d. Glucose concentrations following the GTT did not differ among controls and horses given 8 mg Cr/d. Following glucose infusion, serum insulin concentrations were greater (P < 0.05) in horses fed 2 or 4 mg Cr and tended to be greater in those fed 8 mg Cr/d compared with controls. The results of this study indicate that 2 or 4 mg Cr/d from Cr Prop increased insulin sensitivity in adult horses following oral carbohydrate consumption.
四十八匹夸特马（3 至 8 岁）被用于确定以丙酸铬（Cr Prop）形式的膳食铬（Cr）对胰岛素敏感性的影响。马匹根据年龄、体况评分和葡萄糖对浓缩饲料的反应在第 0 天进行分组，并随机分配处理。处理包括 0、2、4 或 8mg/d 的 Cr Prop。马匹每天以 0.2kg/100kg 体重（BW）的速度喂食浓缩饲料，并以 1.75 至 2.0kg/100kg BW 的速度喂食干草。所有马匹在研究开始前均先喂食对照饮食 7 天。在禁食过夜后，于第 0 天和第 28 天浓缩饲料喂养后 0、2 和 4 小时，从颈静脉采集血样，以测定葡萄糖、非酯化脂肪酸和胰岛素。第 42 天进行葡萄糖耐量试验（GTT）。通过颈静脉导管输注葡萄糖，在给药后不同时间采集血样，以测定葡萄糖和胰岛素。第 28 天的血浆葡萄糖受到处理（P<0.05）、时间和处理×时间的影响。与其他处理组相比，每天喂食 4mg Cr 的马匹在 0 小时的血浆葡萄糖浓度较低（P<0.05）。在喂食后 2 小时，与喂食 0 或 8mg Cr 的马匹相比，喂食 0 或 8mg Cr 的马匹的血糖浓度较高（P<0.05）。与喂食 0 或 8mg Cr 的马匹相比，喂食 2mg Cr 的马匹在喂食后 4 小时的血浆葡萄糖浓度较低（P<0.05）。在喂食 2 或 4mg Cr 的马匹中，2 或 4 小时时血浆葡萄糖在接受 2 或 4mg Cr/d 的马匹之间没有差异。血清胰岛素受到处理（P<0.05）、时间和处理×时间的影响。与喂食 4 或 8mg Cr 的马匹相比，喂食 0 或 2mg Cr/d 的马匹在 0 小时的胰岛素浓度较高（P<0.05）。在喂食后 4 小时，与喂食 2 或 4mg Cr/d 的马匹相比，喂食 0 或 8mg Cr 的马匹的胰岛素浓度较高（P<0.05）。在 GTT 后，血浆葡萄糖受到处理（P<0.05）和时间的影响，但不受处理×时间的影响。（P<0.05）。在 GTT 后，与对照组相比，喂食 2 或 4mg Cr/d 的马匹的平均血浆葡萄糖（跨采样时间）浓度较高（P<0.05）。与对照组相比，喂食 8mg Cr/d 的马匹的葡萄糖浓度没有差异。在葡萄糖输注后，与对照组相比，喂食 2 或 4mg Cr 的马匹的血清胰岛素浓度较高（P<0.05），而喂食 8mg Cr/d 的马匹的血清胰岛素浓度则有升高的趋势。本研究结果表明，丙酸铬（Cr Prop）中的 2 或 4mg Cr/d 可增加成年马口服碳水化合物后的胰岛素敏感性。
