Modulatory Effect And Mechanism Of Grape Proanthocyanidins On Broiler Chicks Challenged With Coccidiosis

Grape proanthocyanidins(GPC) is one kind of well-source and typical plant polyphenols,which is rich in skin and seed of grape.Maintains of literatures at home or abroad presented GPC executed antioxidatation,cytoprotection,and more other effects.Multiple and special phosiological functions of GPC have attracted the attention of poultry practitioners,and applicated in poultry industry.Coccidiosis is a common and multiple disease of broiler chicks.Coccidiosis is threatening seriously the development of poultry industry and mainly induces oxidant stress,inhibited immunity and instinal injury.This research aimed at studying the nutritional modulation effect and mechanism of GPC on broiler chicks challenged with coccidiosis,and included the evaluation of antioxidant and promoting immunity effect in vitro,the test of effectiveness in feeding experiment,and feeding experiment post-challenged coccidiosis. Experiment 1. Evaluation of GPC Antioxidant Capacity and Modulating Immunity Effect in vitroThis experiment was designed to evaluate the antioxidant capacity and modulating immunity effect of grape proanthocyanidins in vitro,aimed at offering basis for the application in broiler chicks.In trial 1,the total reducing power,the ability to scavenging the free radiacals,and the inhibiting effect on lipid oxidation of tert-butylhydroquinone at the level of 0.5 mg/m L,Vitamin C at the concentration of 0.5 mg/m L,GPC at the levels of 0.1,0.5,and 1.0 mg/m L were check.The results showed that the order of total reducing power and the capacity of scavenging the hydroxyl free radical as following.0.5 mg/m L TBHQ>0.5 mg/m L VC>0.1 mg/m L GPC>0.5 mg/m L GPC>1.0 mg/kg GPC;concerned with the ability to scavenging the DPPH free radical,the order of the inhibit rate as following after 5 and 10 minutes.0.5 mg/m L TBHQ< 0.1 mg/m L GPC<0.5 mg/m L GPC<1.0 mg/kg GPC<0.5 mg/m L VC;the order after 15 minutes.0.5 mg/m L TBHQ< 0.1 mg/m L GPC<0.5 mg/m L GPC <0.5 mg/m L VC<1.0 mg/kg GPC;GPC at the level of 0.5 mg/m L significantly inhibited the lipid oxidatation compared with other antioxidants.In trial 2,0,0.24,1.2,6.0,30,and 150 μg/m L GPC was selected to test the effect on the proliferation of peripheral blood lymphocytes(PBLs) and intestinal epithelium γδ T lymphocytes of broilers.The result presented GPC could promote the proliferation of PBLs and intestinal epithelium γδ T lymphocytes and the optimum dosage was 30 μg/m L.In conclusion,GPC has excellent antioxidant and promoting the immunity effect in vitro. Experiment 2.Effect of GPC on Growth Performance and Immunity of Broiler ChicksThis experiment was conducted to investigate the influence of GPC on the growth performance and immunity in broilers.A total of 240 day-old healthy male broiler chicks(Cobb-500)with an average body weight were rando m Ly allotted into 4 treatments with 6 replicates each(n=10).Chicks were fed a basal wheat-soybean meal diet supplemented with 0 mg/kg,7.5 mg/kg,15 mg/kg or 30 mg/kg GPC.The experiment lasted for 42 days.The result showed that GPC significantly reduced feed intake during the 0-6 week and improved feed efficiency(P<0.05),which occured during the growth stage(22-42 days);7.5 mg/kg and 15 mg/kg GPC improved feed efficiency in the growth stage;7.5 mg/kg GPC significantly increased the thymus index at 42 d of age(P<0.05),and 30 mg/kg GPC significantly improved the thymus index of chickens at 21 and 42 d of age(P<0.05)and spleen index at 42 d of age;there were significant improving effect on lymphocyte proliferation at 42 day supplemented with 7.5 mg/kg GPC,while 7.5 mg/kg and 30 mg/kg GPC significantly improved T and B lymphocyte transformation rate at 42 d of age respectively(P<0.05);7.5 mg/kg GPC numerically increased the number of γδ T lymphocyte count in peripheral blood at 21 day without statistical difference(P>0.05)and significantly improved phagocytic index of mononuclear phagocyte system(P<0.05)at 42 d of age;15 mg/kg GPC could significantly elevated lysozyme content at both 21 and 42 d of age(P<0.05),while 30 mg/kg GPC just significantly improved the lysozyme content(P<0.01)and decreased carbon clearance index and phagocytic index(P<0.05)at day 42.GPC at the dosage of 7.5 mg/kg-15 mg/kg can improve growth performance and immunity in broilers. Experiment 3. Effect of GPC on the Carcass Charecter,Jejunum Morphology and Blood Parametre of Broiler ChicksThe study was conducted to explore the effect of GPC on the carcass traits,jejunum morphology,blood indices in broiler chicks.A total of 280 newly-hatched healthy male broiler chicks(Cobb-500)were randomly allotted into 4 treatments with 7 replicates each(n=10)and fed diets with 0,7.5,15,or 30 mg/kg GPC.The experiment period was 42 days.Dietary GPC improved the growth performance during Grower phase(d 22-42)by decreasing ADFI and maintaining the ADG.GPC supplementation obviously elevated the breast muscle yield on d 42 and improved jejunum morphology on both d 21 and d 42 d.Chicks fed 7.5 and 15 mg/kg GPC gained more breast muscle yield and exhibited improved jejunum morphology.Dietary GPC at level of 15 mg/kg markedly elevated the total superoxide dismutase(T-SOD)activity on d 21 and 42,and GPC supplementation level at 7.5 mg/kg improved the T-SOD activity and decreased lipid peroxidation malondialdehyde content on d 42,whereas 30 mg/kg GPC had no effects on antioxidant status than the control.The activity of alkaline phosphatase(d 21),alanine a minotransferase(d 42),and the concentration of creatinine(d 21 and 42)were obviously elevated by the diet with 30 mg/kg GPC.In summary,dietary GPC at the levels of 7.5 and 15 mg/kg improved the growth performance,increased breast muscle yield and ameliorated antioxidant status and jejunum morphology,whereas GPC supplementation level at 30 mg/kg adversely affected the blood biochemical parameters in broiler chicks.The overall results indicated that GPC(7.5-15 mg/kg)had the potential to act as a promising feed addictive in broiler chicken. Experiment 4. Effect of GPC on Growth Performance, Immunity, and Antioxidant Status of Broiler Chicks Challenged with Eimeria tenellaThis study was conducted to reseach the effect of GPC on the performance,immunity and antioxidant status of broiler chicks challenged with Eimeria tenella.A total of 350 newly-hatched healthy male broiler chicks(Cobb-500)were rando m Ly allotted into 5 treatments with 7 replicates(n=10)and fed diets with 0(blank control group, BC),0(negtive control group, NC),7.5,15,or 30 mg/kg GPC.At the age of 14 d,broiler chicks in negative control and GPC addition treatments were challenged with 5×104 sporulated oocysts,whereas chicks in the positive control treatment was challenged with physiological saline in the same volume.The experiment lasts 42 days.No significant difference of performance of broiler chicks during 1-14 days was observed.During 15-21 days(during 1-7 d post-infection,during 1-7 d PI),NC group significantly lower ADG compared with BC group(P<0.05)and all GPC supplementation groups improved the ADG,but not significant difference was observed.During finisher phase(22 to 42 days),the infection of coccidiasis significantly reduced ADG.But chickens from NC+7.5 mg/kg GPC group and NC+15 mg/kg GPC group showed significantly higher ADG(P<0.05)in comparison with NC group.ADFI results showed NC+30 mg/kg GPC group had significant reduction(P<0.05).In the whole period,performance was significantly improved in groups supplemented 7.5 mg/kg and 15 mg/kg GPC,compared with NC(P<0.05).GPC supplemented with the diet significantly decreased the lesion score,bloody diarrhea,and oocyst output on d 8 PI in comparison with NC group(P<0.05).On 8th day PI,the supplementation of GPC significantly reduced MDA content and elevated the activity of T-SOD and CAT,and T-AOC,compared with NC group(P<0.05).GPC significantly decreased the level of NO and the activity of i NOS induced by the infection of coccidiosis(P<0.05).The infection of Eimeria tenella significantly improved the activity of lysozyme,whereas GPC had better increased effect but no significant difference was observed.Compared with BC group,the infection of coccidiosis significantly the spleen index,but GPC had no obvious change related to BC group.GPC significantly improved the T lymphocyte conversion rate,compared with the BC group.Related to other groups,7.5 and 15 mg/kg GPC significantly increased B lymphocyte conversion rate. The challenge significantly increase the percent of γδ T lymphocytes in blood, and the supplementation of GPC had a tendency to futther improve the rate. The infection of coccidiosis significantly induced the increasement of the ileum epithelium lymphocyte(IEL)number and secretory Ig A(s Ig A)in the cecum sinus,and GPC improved the effect further.In conclusion,GPC improved the performance,immunity and antioxidant status,and resist the inflammatory response induced by Eimeria tenella. 7.5 and 15 mg/kg GPC had better effect.This research evaluated the antioxidant and promoting immunity effect of GPC, and studied the effect of GPC on nornal broiler chicks, and investigated the effect and mechanism of GPC on the infection of coccidiosis in broiler chicks. Our results showed, GPC had excelent antixodant and promoting immunity effect, and could resist the infection of coccidiosis by inhibiting the oxidant stress and improving the immunity.