Abstract: (147 Views)
Introduction and Objective: The occurrence of environmental stress causes a decrease in performance in industrial poultry flocks; Therefore, it is necessary to control these tensions. The aim of this study was to evaluate the effect of heat stress and density on performance, blood biochemical parameters, immunological response, meat quality and intestinal morphology.
Material and Methods: A total of 868 one-day-old as-hatch broilers (Arian) were used in a 2x2 factorial design with 4 treatments and 7 replications. The experimental groups included 2 levels of density (14 and 17 broilers per square meter from the beginning of the rearing period) and 2 levels of temperature (standard and heat stress in the last two weeks of rearing). The parameters investigated in this experiment were performance, some biochemical parameters, intestinal morphology, immune system strengthening, and meat quality.
Results: The results showed that performance parameters were affected by treatments throughout the entire period, so that, according to the main effects, daily weight gain increased at standard temperature and density, and decreased density significantly improved the feed conversion ratio (P˂0.01). The weight of the bursa of Fabricius, thymus, spleen and the diameter of the right ventricles of the heart were higher in treatments under standard temperature with both densities of 14 and 17 compared to other treatments (P˂0.01). In birds under heat stress, the number of lymphocytes decreased and the number of heterophils increased (P˂0.01). Antibody production titer against sheep erythrocytes decreased in the primary response under heat stress (P˂0.01). Also, regarding the main effects, heat stress and increased density increased serum alanine transferase and malondialdehyde levels (P˂0.01). Heat stress and high density caused a decrease in the meat quality of broiler chickens (P˂0.01). Villi height, crypt depth, muscular layer thickness and absorption area in the broiler chickens reared under standard density were significantly increased (P˂0.01).
Conclusion: In general, it can be concluded that in the conditions of heat stress, the optimal density is 14 chickens per square meter, and it is suggested to use this density during heat stress to achieve maximum productivity.
Material and Methods: A total of 868 one-day-old as-hatch broilers (Arian) were used in a 2x2 factorial design with 4 treatments and 7 replications. The experimental groups included 2 levels of density (14 and 17 broilers per square meter from the beginning of the rearing period) and 2 levels of temperature (standard and heat stress in the last two weeks of rearing). The parameters investigated in this experiment were performance, some biochemical parameters, intestinal morphology, immune system strengthening, and meat quality.
Results: The results showed that performance parameters were affected by treatments throughout the entire period, so that, according to the main effects, daily weight gain increased at standard temperature and density, and decreased density significantly improved the feed conversion ratio (P˂0.01). The weight of the bursa of Fabricius, thymus, spleen and the diameter of the right ventricles of the heart were higher in treatments under standard temperature with both densities of 14 and 17 compared to other treatments (P˂0.01). In birds under heat stress, the number of lymphocytes decreased and the number of heterophils increased (P˂0.01). Antibody production titer against sheep erythrocytes decreased in the primary response under heat stress (P˂0.01). Also, regarding the main effects, heat stress and increased density increased serum alanine transferase and malondialdehyde levels (P˂0.01). Heat stress and high density caused a decrease in the meat quality of broiler chickens (P˂0.01). Villi height, crypt depth, muscular layer thickness and absorption area in the broiler chickens reared under standard density were significantly increased (P˂0.01).
Conclusion: In general, it can be concluded that in the conditions of heat stress, the optimal density is 14 chickens per square meter, and it is suggested to use this density during heat stress to achieve maximum productivity.
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