تاثیر سطوح مختلف عنصر روی بر عملکرد، کیفیت تخم‌مرغ و فراسنجه‌های ایمنی مرغان تخمگذار در پرورش متراکم و توصیه شده

زمینه مطالعاتی: عنصر روی جزء ضروری آنزیم کربونیک آنهیدراز رحمی است که نقش مهمی در تشکیل پوسته تخم‌مرغ دارد. هدف: به منظور بررسی تاثیر سطوح مختلف عنصر روی بر عملکرد، کیفیت تخم‌مرغ و فراسنجه‌های ایمنی مرغان تخم‌گذار در شرایط پرورش متراکم این آزمایش انجام شد. روش کار: تعداد 160 قطعه مرغ تخم‌گذار سویه ‌های-لاین 36w- در سن 60 هفتگی به مدت 10 هفته استفاده شد. تیمارهای مورد بررسی شامل دو سطح تراکم (توصیه شده (3 مرغ به ازای هر قفس) و متراکم (5 مرغ به ازای هر قفس) ،) و 4 سطح روی از منبع روی-متیونین (40، 80، 120 و 160 میلی‌گرم در کیلوگرم جیره) بودند که در قالب طرح کاملاً تصادفی با آرایش فاکتوریل 4×2 با 8 تیمار اجرا شد نتایج: افزودن سطوح مختلف روی در شرایط متفاوت تراکم نتوانست مصرف خوراک و ضریب تبدبل خوراک را تحت تاثیر قرار دهد. سطوح 120 و 160 میلی‌گرم در کیلوگرم روی باعث کاهش معنیدار درصد تولید تخم‌مرغ و وزن تخم‌مرغ در مقایسه با سطح 40 میلی‌گرم در کیلوگرم روی در مرغان تخم‌گذار شد. مقاومت پوسته تخم‌مرغ با افزایش سطح روی جیره افزایش و واحد هاو در پرندگان پرورش یافته در شرایط متراکم نسبت به تراکم توصیه شده کاهش یافت (0.05

effect of different zinc levels on performance, egg quality traits and immune response of laying hens reared under high and recommended stock density

introduction: zinc (zn) is required for many enzymatic and metabolic functions in the animal’s body (prasad and kucuk 2002). also, it affects the antioxidant defence system, where deficiency of zn increases oxidative damage to cell membranes (prasad and kucuk 2002). zn was assumed to improve the antioxidant capacity (liu et al., 2011) since zn is necessary for the structure and function of superoxide dismutase, which protecting the brain, lungs, and other tissues from oxidation (noor et al., 2002). however, it has been suggested that zn increases the synthesis of metallothionein, a cystine-rich protein that acts as a free radical scavenger (oteiza et al. 1996). nys et al. (1999) reported that the deficiency of zn decreased egg production and eggshell quality linked to its role as a cofactor in the enzyme carbonic anhydrase, which is essential for shell deposition. the nrc (1994) recommends a level of 40–75 mg/kg of zn in various poultry diets. due to the high amount of phytate, zn can be less bioavailable, despite the high level of zn available in pulses and cereals. therefore, this micronutrient can be supplemented to diets of livestock and poultry (sahin et al. 2009). zno and znso4 are the two most common inorganic zn supplements used for poultry diets (batal et al. 2001). the present study has examined the effects of zn supplementation of laying hens on performance, egg quality traits and immune response under high stock density.material and methods: this experiment was conducted to evaluate the effects of dietary inclusion of different levels of zinc on performance, egg quality traits and immune response of laying hens under high stock density with 160 hy-line w-36 leghorn hens for 10 weeks. treatments consisted of different levels of zinc (40, 80, 120 and 160 ppm) and 2 cage densities [3 hens/cage (recommended) or 5 hens/cage (high density) (38 × 38 × 40 cm)], that was performed in completely randomized design with 2×4 factorial arrangement with 5 replicates. the basal diet was formulated to meet all of the nutrient specifications according to the hy- line w-36 recommendations (hy-line international, 2007). the first 2-wk (61–62 wk of age) was considered as the adaptation period. the main trial period commenced from 63 wk of age and lasted for 8 weeks. lighting program was set on 16 light: 8 dark using an artificial light in a windowless house. the hens had free access to feed and water at all times.the temperature was maintained at 20±2 °c throughout the study. egg production and egg weight were recorded daily and feed intake (fi), feed conversion ratio (fcr) and egg quality were recorded weekly.