Effects of Dietary Manganese Proteinate or Chromium Picolinate Supplementation on Plasma Insulin, Glucagon, Glucose and Serum Lipids in Broiler Chickens Reared Under Thermoneutral or Heat Stress Conditions.

Abstract

A study was conducted to investigate the effects of supplemental chromium picolinate (CrPic) or manganese proteinate (MnPro) on heat-distressed broiler chickens. In a completely randomized design, diets were supplemented with either 200 or 400 ug Cr/kg as CrPic or 0, 60 and 240 mg Mn/kg as MnPro and fed to broilers under heat stress (HS) or thermoneutral (TN) conditions. Commercial broilers were reared in brooder pens and fed the experimental diets from Day 1 to 21 and then assigned the same dietary treatments in one of two environmentally controlled chambers. One chamber was maintained at 23.9 °C, whereas birds in the second chamber were exposed to 8-h of 23.9 °C, 4-h of 23.9 to 35 °C, 4-h of 35 °C and 8-h of 35 to 23.9 °C. At 9 wks, plasma concentration of insulin (I) was lower (p<0.01) in birds supplemented with 240 mg Mn /kg compared with 60 mg Mn/Kg. However, neither glucagon (G) concentration, I:G ratio, or glucose were affected (p>0.05) by dietary treatment regimen. Heat stress lowered insulin (p<0.004), increased glucagon (p<0.002) and lowered I:G ratio (p<0.02). Serum concentrations of non-esterified fatty acids were lower in high Mn supplemented group, but triglycerides (TG), total cholesterol (CHOL), high-density lipoprotein (HDL) cholesterol, and HDL: CHOL ratio were not affected (p>0.05) by dietary treatment. Heat stressed birds receiving no Mn supplementation had lower HDL: CHOL ratios (p<0.02) while HS reduced serum TG concentrations (p<0.04). Data suggest that under conditions of this experiment, Cr and Mn may play a part in lipid and/or carbohydrate metabolism in broilers.