Efficacy Of Dietary Selenium And Vitamin E Alleviate Immunological Stress In Broilers

Two experiments were conducted in the present study to determine the effect of preslaughter immunological stress on antioxidant capacity and meat quality and the regulations of dietary selenium and vitamin E on immunological stress in broiler by injection of lipopolysaccharide (LPS) in order to provide a beneficial accumulation to establish the technology of nutrient regulation against stress in broiler industry.In trial one, effects of preslaughter immunological stress induced by lipopolysaccharide (LPS) on antioxidant capacity and meat quality of broilers were investigated. Twenty-four broiler chickens (39-day-old) with similar body weight (BW) were randomly assigned to three treatments:sham injection of saline (control), daily subcutaneous (s.c.) injection of LPS (1000μg/kg or2000μg/kg of BW) for3days. The results showed that average daily feed intake and BW of chickens significantly decreased in the LPS treatment (P<0.05), while F/G significantly enhanced (P<0.01); PH24h of breast muscle significantly decreased (P<0.05), water-loss rate of breast muscle increased remarkably (P<0.01); Yellowness (b*) on the3rd day and lightness (L) on the6th day of breast muscle stored at4℃improved significantly (P<0.05). PH45min and PH24h of thigh muscle decreased significantly in the LPS treatment (P<0.01). Redness (a*) of thigh muscle stored at4℃for3days significantly increased (P<0.05); The plasma MDA of breast and thigh muscle significantly enhanced in the LPS treatment (P<0.05), meanwhile, the total antioxidant capacity (T-AOC) levels significantly suppressed (P<0.01). The present results suggest that preslaughter LPS-induced immunological stress could rise body oxidative damage and decrease oxidation resistance of boilers, resulting in poor growth performance and meat quality, moreover, these negative effects depend on stress intensity.In trail two, effects of dietary selenium and vitamin E on growth performance, oxidation resistance, meat quality and immunity in broiler chickens exposed to LPS-induced immunological stress was evaluated. A total of200one-day-old broiler chicks (Cobb500) with similar body weight were randomly divided into four treatments with5replicates of10birds. The first treatment was fed a corn-soybean meal basal diet, while the residual treatments were fed the basal diet supplemented with selenium0.2mg/kg, vitamin E200 mg/kg, or selenium0.2mg/kg+vitamin E200mg/kg, respectively. All the treatments were divided into two groups (A, B) at22days of age. Subsequently, the group B was injected at abdomen s.c. with LPS (1000μg/kg BW) for3times every other day, while the group A was injected with saline and served as control. The results were as follows:(1)The average daily feed intake and BW gain were suppressed, and F/G increased significantly (P<0.01) during LPS injection (22-27days). There was significant interaction of selenium, vitamin E and LPS treatments for daily feed intake (P<0.05). However, the LPS treatment had no significant influence on growth performance in28～42days (P>0.05).(2)The abdominal fat percentage of broilers was significant decreased, while the LPS treatment had no significant impact on dressing percentage, semi-eviscerated percentage, eviscerated percentage, breast muscle percentage and leg muscle percentage of42-day-old broilers (P>0.05).(3)At27days of age, the variation of pH, color, shear force and water-loss rate of breast muscle were not significant difference among the treatments (P>0.05).At42days of age, compared with control, the LPS treatment had no significant influence on pH, color, shear force and water-loss rate of breast muscle (P>0.05).There was significant interaction of selenium and LPS on shear force (.P<0.05).At the same time, the vitamin E treatment significant impact on the pH at24hours, lightness(L*), yellowness(b*)(P<0.05) and redness(a*)(P<0.01).(4)At27days of age, compared with control, the LPS treatment significantly increased MDA levels of the plasma and breast (P<0.01), activity of GSH-Px (P<0.01), while the LPS treatment significantly declined the breast and bursa of fabricius activity of GSH-Px (P<0.05), bursa of fabricius T-AOC levels (P<0.01).Dietary selenium significantly decreased the plasma MDA (P<0.05), breast MDA (P<0.05), bursa of fabricius MDA (P<0.05), and significantly enhanced the plasma T-AOC (P<0.05), bursa of fabricius T-AOC (P<0.05), plasma activity of GSH-Px (P<0.01), breast activity of GSH-Px (P<0.01).Dietary vitamin E significantly declined the plasma and breast MDA levels (P<0.01), bursa of fabricius activity of GSH-Px (P<0.01), and significantly increased the plasma and bursa of fabricius T-AOC levels (P<0.05). At42days of age, there was no significant influence on plasma and breast muscle MDA levels, T-AOC levels (P>0.05), and significantly decreased the breast and bursa of fabricius activity of GSH-Px (P<0.01).(5) The LPS treatment significantly improved the spleen index (P<0.0l) and declined the bursa of fabricius index of27-day-old broilers (P<0.05).However, the LPS treatment had no significant influence on immune organ index of42-day-old broilers (P>0.05). There was significant interaction of vitamin E and LPS treatment on thymus index of27-day-old broilers (P<0.05), spleen index and newcastle disease antibody level of42-day-old (P<0.05). Dietary vitamin E significantly enhanced the newcastle disease antibody level of35-day-old broilers (P<0.05), thymus index and serum immunoglobulin M (IgM) of27-day-old broilers (P<0.05). Dietary selenium significantly increased the newcastle disease antibody level of35-day-old broilers (P<0.05).These results suggested that growth performance, abdominal fat percentage, antioxidant capacity, bursa of fabricius index were significantly declined and spleen index was significantly enhanced when broilers suffered from acute immunological stress induced by LPS. Moreover, dietary supplementation with selenium and vitamin E during early growth and acute immunological stress stage could not completely eliminate the injuries of stress for broilers. However, dietary supplementation with selenium and vitamin E was favorable for improving immunity and oxidation resistance to alleviate LPS-induced immunological stress, also contributed to chickens retrieve from stress state to the normal.