Eggshell quality deterioration associated with heat stress is a well-known phenomenon. The involvement of the 28-kDa calcium-binding protein (calbind

The objective of the present study was to examine the effects of nano-selenium on growth performance, antioxidative status, and immune function in broiler chickens reared under thermoneutral (22±1°C) or high ambient temperature (35±1°C) conditions. Thirty-six broiler chicks at 15d old were randomly divided into 6 treatments in a 3×2 factorial design. The main factors included the dietary supplementation (basal diet without Se supplementation [control], basal diet with 0.3 mg of nano-elemental Se per kilogram of diet [nano-Se], and basal diet with 0.3 mg of sodium selenite per kilogram of diet [SSe]) and the ambient temperature challenge (22±1°C or 35±1°C). The birds were given the experimental diets from 15 to 30 d of age. High ambient temperature significantly depressed body weight gain, feed intake, feed conversion ratio, breast muscle weight, and abdominal fat weight, while feeding nano-Se clearly alleviated these negative effects of high ambient temperature. In addition, feeding nano-Se increased glutathione peroxidase mRNA expression in liver and alleviated the negative effects of high ambient temperature via reducing the malondialdehyde content in liver and breast muscle. Furthermore, feeding nano-Se increased mRNA expression of cytokine genes (interleukins 2 and 6) under both thermoneutral and high ambient temperature conditions. Under both thermoneutral and high-temperature conditions, broiler chickens fed nano-Se had higher Se and vitamin E concentrations in breast muscle than broiler chickens fed the control diet. In contrast, feeding SSe at the same dose as nano-Se did not alleviate the negative effects of high ambient temperature on broiler chickens. In conclusion, dietary supplementation with nano-Se at 0.3 mg/kg diet might enhance growth performance by improving antioxidative or immune properties in broilers reared under high ambient temperature.

A two level factorial experiment (3 × 3) was designed to evaluate the effect of dietary inclusion level of probiotic and breed on productive performance, immune status and egg quality characteristics in laying hens reared under high ambient temperature. A total of 216, 32-week-old laying hens representing three different breeds (White Leghorn, Saudi black and Saudi brown) were randomly assigned to three dietary treatments (0, 200 and 400 g/t feed) in a 90-d experiment. The current results indicated that the inclusion of probiotics in layer diets did not appear to cause any adverse effects on egg production traits compared with non-treated hens. Dietary supplementation with probiotics at 400 ppm level significantly (p < .05) increased shell thickness compared to non-treated laying hens. Moreover, an improvement in eggshell quality and breaking strength in hens fed a diet containing probiotics was observed under high ambient temperature. Also, plasma cholesterol and triglyceride were reduced in laying hens fed a diet supplemented with probiotics. Furthermore, probiotic inclusion significantly increased IgM immunoglobulin concentration in laying hens fed a diet containing either 200 or 400 ppm compared with untreated hens. Concerning breed effect, Saudi black laying hens recorded significantly (p < .02) higher egg mass compared with the other breeds. Also, both Saudi chicken breeds exhibited significantly higher cell-mediated response and IgM concentration compared with Leghorn hens.

This study was conducted to evaluate the effect of zinc-methionine (ZnM) on growth performance, nutrient utilization, antioxidant status and immune response in broiler chickens reared at high ambient temperature. A total of 480 one-day-old chicks were randomly distributed into 24 floor pens (20 chicks/pen) and were given either a control diet, 0 ZnM (G0) or 25, 50 and 100 mg/kg ZnM (G1, G2 and G3, respectively). The growth performance was significantly affected by the treatments, ZnM supplementation increased body weight gain and improved feed conversion (p < .05) in broilers. Protein utilization was improved by feeding ZnM (p < .05). Plasma total cholesterol was decreased, while plasma HDL-cholesterol was tending to be increased. Interestingly, an increase in ZnM supplementation enhanced Zn concentrations (p < .05) in breast muscle along with a reduction in malondialdehyde concentration and saturated fatty acids (p < .05) and an augmentation in unsaturated fatty acids (p < .01). Dietary ZnM supplementation resulted in a significant increase in serum glutathione peroxidase concentration which accompanied with an improving in humoral immune response. It could be concluded that dietary organic Zn supplementation improved growth performance, nutrient digestibility, Zn content in raw meat, antioxidative properties and humoral immunity and reduced meat lipid peroxidation in broilers under high ambient temperature.