پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 49 3 2018 11 22 Effect of organic zinc supplement on performance, immunity responses, cecal microbial population and digestibility of nutrients in broiler chickens reared at high stocking density Effect of organic zinc supplement on performance, immunity responses, cecal microbial population and digestibility of nutrients in broiler chickens reared at high stocking density 393 404 69370 10.22059/ijas.2018.252664.653620 FA Vrya Rasooli Former M. Sc. Student, Department of Animal Science, Faculty of Animal Science and Food Industry, Agricultural Sciences and Natural Resources University of Khuzestan, Iran Somayyeh Salari Associate Professor, Department of Animal Science, Faculty of Animal Science and Food Industry, Agricultural Sciences and Natural Resources University of Khuzestan, Iran Ahmad Tatar Assistant Professor, Department of Animal Science, Faculty of Animal Science and Food Industry, Agricultural Sciences and Natural Resources University of Khuzestan, Iran Journal Article 2018 02 18 In order to investigate the effect of organic zinc (Zn) supplement in broiler chicken nutrition that reared at high stock density, this experiment was done by using 2 levels of density (10 and 16 birds/m2) and 4 levels of Zn (40, 80, 120 and 160 ppm) in a completely randomized design with 4×2 factorial arrangement. The results showed that birds with higher stocking density had lower feed intake (FI) and feed conversion ratio (FCR) compared to those in normal density from d 1-21 and birds with normal stocking density had lowest FI and FCR from d 22-42 (P<0.05). Cecal population of Coliform decreased in normal and high stock density by increasing Zn level in the diet (P<0.05). Apparent ileal digestibility of crude protein significantly increased by increasing the levels of Zn in the diet in normal and high stock density (P<0.05). These data suggest that dietary supplementation of Zn significantly increased ileal digestibility of crude protein and organic matter and also, decreased cecal population of Coliform and E. coli in high and normal stocking density without affecting the performance of broilers.  In order to investigate the effect of organic zinc (Zn) supplement in broiler chicken nutrition that reared at high stock density, this experiment was done by using 2 levels of density (10 and 16 birds/m2) and 4 levels of Zn (40, 80, 120 and 160 ppm) in a completely randomized design with 4×2 factorial arrangement. The results showed that birds with higher stocking density had lower feed intake (FI) and feed conversion ratio (FCR) compared to those in normal density from d 1-21 and birds with normal stocking density had lowest FI and FCR from d 22-42 (P<0.05). Cecal population of Coliform decreased in normal and high stock density by increasing Zn level in the diet (P<0.05). Apparent ileal digestibility of crude protein significantly increased by increasing the levels of Zn in the diet in normal and high stock density (P<0.05). These data suggest that dietary supplementation of Zn significantly increased ileal digestibility of crude protein and organic matter and also, decreased cecal population of Coliform and E. coli in high and normal stocking density without affecting the performance of broilers.  https://ijas.ut.ac.ir/article_69370_120d0d4e1bfcf5ecd5187428e08f3be2.pdf