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.

Contents The objectives of this study were to investigate the effects of flaxseeds and/or fenugreek seeds as a source of phytoestrogens in laying feed on productive performance, egg quality, yolk fatty acids, plasma profile and antioxidative status in aged laying hens. A total of 120 Bovans Brown hens at 65 weeks of age were housed individually in laying cages in an open‐sided building under a 16‐hr light: 8‐hr dark lighting schedule. Hens were randomly divided into four experimental treatments (n = 30 each): (a) control (basal diet without any supplementation); (b) 1 g/kg of flaxseeds; (c) 1 g/kg of fenugreek seeds; and (d) combination of 1 g/kg flaxseeds and 1 g/kg fenugreek seeds from 65 to 71 weeks of age. Hen‐day egg production and egg mass were significantly increased by dietary supplementation of flaxseeds and/or fenugreek seeds, while feed intake was not affected; thus, feed conversion ratio was improved (p < 0.05). Weights of egg, albumen, yolk and shell were increased by the dietary treatments. Shell thickness and yolk colour were improved by supplementation of flaxseeds and/or fenugreek seeds. Yolk crude protein was not significantly affected by treatments; however, crude fat and calcium contents in yolk were increased and egg yolk cholesterol content was decreased. Interestingly, dietary supplementation of flaxseeds, fenugreek seeds and their combination had a significant positive effect on plasma luteinizing hormone, follicle‐stimulating hormone, oestradiol‐17β and triglycerides. Inclusion of flaxseeds and/or fenugreek seeds in the diets enhanced the serum glutathione peroxidase and superoxide dismutase activities and reduced the malondialdehyde and total cholesterol concentrations in plasma. Dietary supplementation of flaxseeds and/or fenugreek seeds increased α‐linolenic and linoleic acids in egg yolk. It could be concluded that inclusion of mixed sources of phytoestrogens in diets improved laying performance, egg quality, the antioxidative status, hormonal profile and steroidogenesis in aged laying hens.