Effects Of Immunological Stress On Blood Indexes And Meat Quality Of Broilers

Two experiments were designed to study the effects of immunological stress on blood hormones,biochemical indexes and meat quality of broilers, as well as the effects of immunological stress on growth performance, antioxidation, energy metabolism, carcass traits and fatty metabolism of broilers.Experiment 1 Effects of chronic immunological stress and vitamin C on blood indexes and meat quality of broilersOne hundred 21-day-old AA male broilers were randomly assigned into four treatments, each treatment had 5 replicates,5 broilers per replicate. Two experimental diets were formulated as basal diet and diet with vitamin C (400mg/kg), Each broiler was injected with LPS on days of 28, injection doses were: 100μg/kg.BW (28d) , 200μg/kg.BW (30d) , 200μg/kg.BW (32d) , 250μg/kgBW (35d) , 250μg/kg.BW (37d) , 400μg/kg.BW (39d) , 400μg/kg.BW (41d) , the control group was injected with saline. Broilers were weighted at the beginning and the end of the experiment. At the day of 42, blood was collected to prepare plasma and serum for testing hormones,biochemical indexes of broilers. The breast muscle and leg muscle were collected for measuring meat quality. The results showed as follows: (1) LPS significantly decreased the ADG (P＜0.05) ; (2) Compared with the vitamin C treatment, LPS group significantly affected the hormones and blood chemical indexes (P＜0.05) . Compared with the control group, LPS significantly increased the content of Cortisone, TNF-α(P＜0.05) , and improved MDA level of plasma and muscle (P＜0.01) . (3) LPS decreased the pH of muscle (P＜0.05 ) , and increased the drip loss of leg muscle (P＜0.05) . But the immunologiocal stress didn't affect the drip loss of breast muscle of broiler meat significantly . Muscle fasciculus areas of broiler were significantly increased by LPS (P＜0.05) , The percentages of AF and IMF were significantly improved by LPS (P＜0.05) . (4) The relative contents of MUFA and SEA in broilers' breast muscle were significantly increased by LPS (P＜0.05) . The basal diet with vitamin C significantly increased the relative contents of PUFA in broilers' breast muscle (P＜0.05) . LPS significantly affected the relative contents of FA in leg muscle of broilers. LPS significantly improved the relative contents of linoleic acid in broilers meat (P＜0.05) , but the relative contents of total MUFA was significantly increased by LPS (P＜0.05 ) .Experiment 2 Effects of acute immunological stress on blood indexes and meat quality of broilersOne hundred 14-day-old AA male broilers were randomly assigned into four treatments, each treatment had 5 replicates,5 broilers per replicate. At the 21, 23, 25 days of age, three treatments were injected with LPS 250μg/kg BW 500μg/kg BW and 1000μg/kg into abdomen, respectively. Control was injected with sterile saline. Blood were collected after 3h at the first and second injection, and after 24h at the third injection for testing hormone levels and biochemical indexes. Liver and breast muscle were acquired on the day of twenty-sixth for testing meat quality. The results showed as follows: (1) LPS decreased the growth performance . (2) The level of IL-1,IL-6 and TNF-αwere significantly increased by LPS (P＜0.05), LPS significantly improved the level of MDA in plasma and breast muscle (P＜0.05), The level of the plasma SOD was significantly decreased by low-dosage LPS (P＜0.05) The level of the plasma SOD was significantly improved by high-dosage LPS (P＜0.05). The levels of SOD in liver and breast muscle were significantly increased by LPS (P＜0.05) ,LPS significantly increased the levels of plasma CHO,TG of plasma (P＜0.05). (3)LPS significantly increased the level of LD in breast muscle and liver and the level of LDH in liver (P＜0.05) ,but reduced the level of ATP in liver (P＜0.05) . (4) LPS significantly decreased the breast muscle's pH (P＜0.05) . The acute immunologiocal stress didn't affect the drip loss of breast muscle. LPS increased the content of breast muscle and liver fat, decreased the content of breast muscle and liver moisture (P＜0.05) . (7) LPS significantly influenced the metabolism of fatty acids in the Liver (P＜0.05) .