اثرات سطوح مختلف استات روی و سولفات منیزیم بر عملکرد، خصوصیات لاشه و برخی فراسنجههای خونی جوجههای گوشتی تحت شرایط استرس گرمایی

In recent experiment, the effects of different levels of zinc acetate (0, 30 and 60 mg per kg) and magnesium sulfate (0, 300 and 600 mg per kg) was investigated on performance, carcass characteristics and some blood metabolites of broiler chickens under heat stress condition. for this purpose, 450 one-day-old broiler chicks (ross 308) were used in 9 groups, 5 replicate (pens) each with 10 birds per replicate. the experimental treatments were analyzed in a 3×3 factorial experiment based a completely randomized design. all the birds fed the same starter (1 to 21 day of age) and grower (22 to 42 day of age) but different dietary zinc and magnesium. the results showed that zinc acetate improved the feed consumption, body weight gain and feed conversion ratio (p < 0.01). but dietary magnesium sulfate didn’t affect on the performance during whole the experimental period. supplementation of both zinc and magnesium decreased the proportional liver weight (p < 0.01). furthermore, zinc supplementation decreased the jejunum weight and duodenum length (p < 0.01). in addition, zinc supplementation increased the blood hemoglobin (p < 0.01). according the results of current experiment, although supplementation of 30 mg per kg zinc acetate alone had the best effect on performance of broiler chickens and reduced the detrimental effects of heat stress but using both the zinc and magnesium together has no advantage regarding the determined parameters.