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High ambient temperatures compromise performance and productivity through reducing feed intake and decreasing nutrient utilization, growth rate, egg production, egg quality, and feed efficiency, which lead to economic losses in poultry. Environmental stress also leads to oxidative stress associated with a reduced antioxidant status in the bird in vivo, as reflected by increased oxidative damage and lowered plasma concentrations of antioxidant vitamins (e.g., vitamins E, A, and C) and minerals (e.g., Zn). Zinc has an important role in numerous biological processes in avian and mammalian species. For instance, Zn is an essential component of many enzymes, and it has both structural and catalytic functions in metalloenzymes. Furthermore, dietary Zn is required for normal immune function as well as proper skeletal development and maintenance. One of the most important functions of Zn is related to its antioxidant role and its participation in the antioxidant defense system. This work compiles past and present information about the role of Zn in heat-stressed poultry health.

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We evaluated the effects of vitamin C (L-ascorbic acid) and folic acid supplementation on performance, carcass characteristics and concentrations of the oxidative stress markers [malondialdehyde (MDA), homocysteine], adrenocorticotropic hormone (ACTH), vitamins C, E, A, B-12 and folic acid, and mineral status in broiler Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature (34 degrees C, 8 h/d, 0900-1700 h). The birds (n = 150; 10-d-old) kept at 34 degrees C were fed a basal diet (HS group) or the basal diet supplemented with 250 mg of L-ascorbic acid/kg of diet (Vit C group), 1 mg of folic acid/kg of diet (FA group) or both (Vit C + FA group), whereas birds kept at 22 degrees C were fed the basal diet (TN group). Supplementing heat-stressed quail with vitamin C and folic acid improved performance compared to the HS group. Effects generally were greatest in quail supplemented with both. Although supplementation did not consistently restore concentrations to those of the TN group, it increased serum concentrations of the vitamins under study. Furthermore, serum and tissue MDA, homocysteine and ACTH concentrations were lower in the supplemented groups than in the heat-stressed controls. Retention of N, ash, Ca, P, Zn, Fe, Cu and Cr were highest in the Vit C + FA group and lowest in the HS group (P < 0.05). The results of the study indicate that vitamin C and folic acid supplementation attenuates the decline in performance and antioxidant status caused by heat stress. Such supplementation may offer protection against heat stress-related depression in performance of Japanese quail.

This study was conducted to determine the effects of chromium (chromium picolinate, CrPic) supplementation at various levels (0, 200, 400, 800, or 1200 microg/kg of diet) on performance, carcass characteristics, and some serum metabolites of broiler chickens (Ross) reared under heat stress (32.8 degrees C). One hundred fifty old male broilers were randomly assigned to 5 treatment groups, 3 replicates of 10 birds each. The birds were fed either a control diet or the control diet supplemented with either 200, 400, 800, or 1200 microg Cr/kg of diet. Increased supplemental chromium resulted in an increase in body weight (p = 0.01, linear), feed intake (p < or = 0.05, linear), and carcass characteristics (p < or = 0.05, linear) and improved feed efficiency (p = 0.01, linear). Increased supplemental chromium decreased serum corticosterone concentration (p = 0.01, linear), whereas it increased serum insulin and T3 and T4 concentrations (p = 0.01). Serum glucose and cholesterol concentrations decreased (p = 0.01), whereas protein concentrations increased linearly (p = 0.001) with higher dietary chromium supplementation. Results of the present study conclude that a supplementation of diet with chromium at 1200 ppb can alleviate the detrimental effects of heat stress in broiler.

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The objective of the present study was to evaluate anti-diabetic effects of chromium picolinate (CrPic) and biotin supplementations in type 2 diabetic rats. The type 2 diabetic rat model was induced by high-fat diet (HFD) and low-dose streptozotocin. The rats were divided into five groups as follows: (1) non-diabetic rats fed a regular diet; (2) diabetic rats fed a HFD; (3) diabetic rats fed a HFD and supplemented with CrPic (80 mg/kg body weight (BW) per d); (4) diabetic rats fed a HFD and supplemented with biotin (300 mg/kg BW per d); (5) diabetic rats fed a HFD and supplemented with both CrPic and biotin. Circulating glucose, cortisol, total cholesterol, TAG, NEFA and malondialdehyde concentrations decreased (P, 0·05), but serum insulin concentrations increased (P,0·05) in diabetic rats treated with biotin and CrPic, particularly with a combination of the supplements. Feeding a HFD to diabetic rats decreased PPAR-g expression in adipose tissue and phosphorylated insulin receptor substrate 1 (p-IRS-1) expression of liver, kidney and muscle tissues, while the supplements increased (P, 0·001) PPAR-g and p-IRS-1 expressions in relevant tissues. Expression of NF-kB in the liver and kidney was greater in diabetic rats fed a HFD, as compared with rats fed a regular diet (P, 0·01). The supplements decreased the expression of NF-kB in diabetic rats (P,0·05). Results of the present study revealed that supplementing CrPic and biotin alone or in a combination exerts anti-diabetic activities, probably through modulation of PPAR-g, IRS-1 and NF-kB proteins.

This study was conducted to determine the effects of dietary vitamin C (L-ascorbic acid) and vitamin E (alpha-tocopherol acetate) on lipid peroxidation status measured as MDA and serum triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), as well as some other serum metabolite and mineral concentrations of Japanese quails reared under heat stress (34 degrees C). One hundred-eighty 10-day-old Japanese quails were randomly assigned to six treatment groups, three replicates of 10 birds each. Using a 2 x 3 factorial design, the birds received two levels of vitamin C (100 and 200 mg/kg of diet) or three levels of vitamin E (125, 250, or 500 mg/kg of diet). Greater dietary vitamin E and vitamin C resulted in a greater serum T3, T4, and TSH (p = 0.001), but lower ACTH (p = 0.001) concentrations. Serum concentrations of T4 and TSH increased to a greater extent by increasing dietary vitamin C when greater vitamin E levels were fed (interaction, p = 0.001). Serum glucose, urea, triglycerides, and cholesterol concentrations decreased (p = 0.001), while protein and albumin concentrations increased (p = 0.001) when both dietary vitamin C and vitamin E were increased. Serum activities of SGOT and SGPT were not influenced by dietary vitamin C and vitamin E (p > 0.43). However, serum activity of AP increased (p = 0.001) by increasing both dietary vitamin C and vitamin E. Increasing both dietary vitamin C and vitamin E caused an increase in serum concentrations of Ca, P, K (p = 0.001), Fe, and Zn (p = 0.01) but a decrease in serum concentrations of Na (p = 0.001) and Cu (p = 0.01). Interactions between vitamin C and vitamin E were detected for Ca, P, Na, and K (p = 0.001). Greater dietary vitamin C and vitamin E resulted in a greater serum and liver vitamin E, C, and A (p < or = 0.05), but lower MDA (p = 0.001) concentrations. Results of the present study conclude that supplementing a combination of dietary vitamin C (200 mg) and vitamin E (250-500 mg) offers a good management practice to reduce heat stress-related decreases in performance of Japanese quails.