Optimal dietary concentrations of vitamin C and chromium for alleviating the effect of low ambient temperature on serum insulin, corticosterone, and some blood metabolites in laying hens

This experiment was conducted to evaluate the effects of vitamin C (L-ascorbic acid) and chromium (chromium picolinate, CrPic) on serum insulin, corticosterone, and some metabolites in laying hens (Hy-Line) reared under a low ambient temperature (6.2°C). One hundred eighty laying hens (32 weeks old) were divided into six groups, with 30 hens per group. The experiment was designed in a 2 × 3 factorial arrangement using two levels of vitamin C (125 and 250 mg/kg of diet) and three levels of CrPic (200, 400, or 800 μg/kg of diet). The highest values for insulin, total protein, and albumin (P = 0.001) and the lowest values for corticosterone, glucose, triglyceride, and cholesterol (P = 0.001) were obtained when 250 mg of vitamin C was included with either 400 or 800 μg Cr per kg of diet. Interaction between vitamin C and chromium was detected for only insulin (P = 0.03). Serum activities of SGOT and SGPT were not influenced by dietary vitamin C or chromium (P > 0.45); however, serum activity of AP increased (P = 0.001). Increasing both dietary vitamin C and chromium caused an increase in serum concentrations of Ca, P, and K (P = 0.001) but a decrease in serum concentrations of Na (P = 0.001). The results of the present study suggest that dietary supplements of vitamin C and chromium alter serum hormone and metabolite status of laying hens and that supplementing a combination of vitamin C (250 mg/kg of diet) and chromium (400 or 800 μg Cr/kg of diet) can positively influence the performance of laying hens reared under low ambient temperature. J. Trace Elem. Exp. Med. 15:153–161, 2002. © 2002 Wiley-Liss, Inc.