Effects Of Different Vitamin Premixes And Stocking Density On Performance,Health,and Meat Quality Of Broilers

The study was conducted to investigate the effects of different vitamin premixes and stocking density on broiler performance, immune function, anti-oxidant capacity, meat quality and animal welfare. The experiment was arranged in 2×5 factorial design. Factors included 2 stocking density:low-density group (10birds/m2 and high density group(16birds/m2),5 different vitamin premixes:vitamin premixes 1 is ROVIMIX 538 (DSM broiler vitamin products) according to the recommended added amount of 250mg/kg, vitamin premixes 2 is ROVIMIX 538 according to the recommended added amount of 350mg/kg,vitamin premixes 3 is vitamin premixes 1+vitamin A to 10000IU/kg,vitamin premixes 4 is vitamin premixes 1+vitamin E to 100IU/kg,vitamin premixes 5 is vitamin premixes 1+vitamin A and vitamin E (respectively to 10000IU and 100IU/kg).10 groups experiment design was applied,each group replicating 8 times. The trial was lasted for 42d. Test results showed as follows:(1)High stocking density significantly reduced broiler 22-42d,1-42d body weight and 42 days average weight(P<0.001), significantly reduced feed intake 22-42d, 1-42d and increase mortality(P<0.001). There were no significant interactions between vitamin premixes and stocking density on growth performance.Compared with the vitamin premixes 1, the vitamin premixes 2,3,4,5 were alleviated the adverse impact of high feeding density (P>0.05), and the vitamin premixes 4 and vitamin premixes 5 have the best effects.Stocking density had no significant effect on slaughter performance(P>0.05). Vitamin premixes 3 can significantly improve broiler slaughter rate (P<0.05). There were no significant interactions between vitamin premixes and stocking density on slaughtering performance(P>0.05).(2)High stocking density significantly increased the 21 d total protein, globulin, corticosterone concentrations and 42d serum albumin, cholesterol and corticosterone concentrations (P<0.05), leading to broiler stress. Vitamin premixes 4 and 5 have trend to decrease the 21d and 42d corticosterone concentrations in serum to relieve stress. There were no significant interactions between vitamin premixes and stocking density on the total protein, albumin and globulin concentrations (P>0.05).(3)Stocking density and vitamin premixes had no significant effect on the immune organ indexes. High stocking density significantly reduces the Newcastle disease antibody titers of 21 d and 42d, the IgA concentration in serum of 42d, the IL 10 concentration in serum of 21d and 42d, significantly increased IL-6 and TNF-α concentrations in serum of 21 d and 42d, and IL-1β concentration in serum of 42d (P<0.05).The 42d lysozyme of vitamin premixes 2 was significantly higher than the vitamin premixes 1 and vitamin premixes 3.The 21d IL 10 concentration in serum of vitamin premixes 2 and 5 were significantly higher than vitamin premixes 1,3 and 4. The 42d IL-6 concentration in serum of vitamin premixes 4 and 5 were significantly lower than1. The 42d IL-10 content in serum of vitamin premixes 2 was significantly higher than the vitamin premixes1,3 and 4.The 42d TNF-α concentration in serum of vitamin premixes 2,4 and 5 is significantly lower than the premixes of 1. High stocking density significantly reduced broiler 21 d sIgA content of jejunum,42d jejunum sIgA and 42d sIgA content of ileum (P<0.05). The 21 d jejunum sIgA content of vitamin premixes 5 was significantly higher than the vitamin premixes 1 and 3. The 42d jejunum sIgA content of vitamin premixes 5 significantly higher than other vitamin premixes,42d ileum sIgA content of vitamin premixes 4 and 5 was significantly higher than vitamin premixes of 1 and 3 (P<0.05).(4) High stocking density significantly reduced broiler 21 d GSH-PX activity of serum,21d T-SOD activity and T-AOC of liver,42d T-SOD of liver activity, significantly increased the 21d MDA of liver,42d MDA of serum and liver(P<0.05); 21 d T-AOC of liver in vitamin premixes 4 and 5 was significantly higher than the premixes 1,2and3(P<0.05), There were no significant interactions between vitamin premixes and stocking density on antioxidant index(P>0.05).(5) High stocking density significantly increased the drip loss and cooking loss of chest(P<0.05). At high stocking density conditions, the chest drip loss of vitamin premixes 2,3,4and5 is lower than premixes 1 (P>0.05). Stocking density only significantly affected the leg drip loss. There were no significant interactions between vitamin premixes and stocking density on the meat quality (P>0.05).(6) High stocking density significantly increased feather conditions score, hock burn score, footpad burn scores (P<0.05). The feather conditions score, hock burn score, and footpad burn scores of vitamin premixes 2,4 and 5 were significantly better than premixes 1 (P<0.05). The foodpad burn score of vitamin premixes 3 was significantly better than premixes 1 (P<0.05). There were no significant interactions between vitamin premixes and stocking density on the hock burn score and footpad burn scores (P>0.05), but had significant effect on feather condition score (P<0.05).At low stocking density conditions there was no significant difference on feather conditions score in different vitamin premixes. At high stocking density conditions, the feather conditions score of vitamin premixes 1 is significantly higher than the vitamin premixes 2,4and5.Above results suggested that,high stocking density reduce the performance, immune function, antioxidant, meat quality and animal welfare of broiler significantly, the impact on the slaughter performance is not significant. Increase the level of vitamin premix or vitamin A and/or vitamin E can increase broiler antioxidant capacity and immune function, improve broiler welfare and performance significantly, relieve the adverse effect of high stocking density. At high stocking density conditions, improving the level of each vitamin comprehensively (vitamin premixes 2) or improving the level of vitamin E (vitamin premixes 4) get the best results.