| Chicken coccidiosis,as the most common poultry disease in intensive farming,is extremely harmful to the poultry breeding industry,which causes serious economic losses.At present,western medicine antibiotics and immune vaccines are mainly used to control chicken coccidiosis.However,chicken coccidiosis is resistant to antibiotics,and there is a risk of drug residues,while the research and development of immune vaccine is expensive and difficult.Studies have shown that traditional Chinese medicine extracts with no chemical hazards and no drug residues are expected to be used as drugs to prevent and treat coccidiosis.It has been reported that Eupolyphaga sinensis Walker Peptide(ESWP)and Grubs Peptide(GP)have good antioxidant and immunoregulatory effects.At present,using traditional Chinese medicine extract as feed additive to reduce the harm of chicken to coccidia infection by enhancing antioxidant stress and regulating immune function,so as to prevent and alleviate chicken coccidiosis has become a research hotspot.Based on the antioxidant and immunoregulatory effects of ESWP and GP,the experiment was to investigate the production performance,antioxidant,immunoregulatory and anti-coccidiosis effects of polypeptide extracts on broilers infected with Eimeria coccidia,to improve the immune function of poultry under stress from the perspective of nutritional regulation.Experiment one:To investigate the antioxidation effect of polypeptide extracts of ESW and Grubs in vitro.The ability of scavenging free radicals,reducing antioxidants and inhibiting lipid peroxidation of the polypeptide extract was determined.The results showed that the polypeptide extract at the proportion of 1:1 had the strongest scavenging effect on O2-and-DPPH free radicals,the antioxidant activity was close to that of the positive drug control group,and the content of MDA decreased.The results show that the polypeptide extracts could scavenge free radicals,inhibit lipid peroxidation and reduce autooxidation,which exhibit good antioxidant effects in vitro.Experiment two:To investigate the immunomodulatory effect of polypeptide extracts of ESW and Grubs in vitro.The transforming ability of chicken peripheral blood lymphocytes and the viability of mouse macrophages(RAW264.7)were measured by MTT,and the phagocytosis of RAW264.7 cells was detected by neutral red method and flow cytometry.The results show that the polypeptide extract with the proportion of 1:1 had the highest lymphocyte transformation rate,and the viability of RAW264.7 cells were relatively high which reached 73%and 98%respectively.There was the strongest phagocytosis ability and the highest positive cell rate of RAW264.7 cells in ESWP and GP combination group.The results showed that polypeptide extract could improve chicken lymphocyte transforming and macrophage phagocytosis ability,which have a certain immune regulation effects.Experiment three:To investigate the effects of polypeptide extracts of ESW and Grubs on the production performance,anticoccidial effect,immune function,antioxidant function and meat quality of broilers infected with Eimeria.The 1st day healthy broilers were randomly divided into 6 groups:The broilers in control and red control group were fed a basic diet,chickens in salinomycin group were fed a basic diet supplemented with salinomycin(60mg/kg),chickens in Walker polypeptide(ESWP)group were fed a basic diet supplemented with ESWP(100mg/kg),and chickens in Grub polypeptide(GP)group were fed a basic diet supplemented with a GP(100mg/kg),chickens in the combined polypeptide(ESWP&GP)group were fed a basic diet added ESWP(100mg/kg)and GP(100mg/kg).Except for control group,all broilers were challenged with Eimeria tenella oocysts 5×103,when they be raised on 14th day.The growth performance,organ index,blood biochemical and antioxidant and immune function indexes of the broilers were measured at 21 days and 42days respectively.The results showed that there was no significant difference in the growth performance(daily weight gain,feed intake,and feed-to-weight ratio).When chickens were infected with coccidia for 7 days,the score of the intestinal injury in ESWP&GP group was significantly lower than that in red control group.When chickens were infected with coccidia for 4th-7th days,the number of oocysts excreted in the red control group reached about 11.95×104,while the number of oocysts excreted in the combined peptide group was significantly lower than that in the red control group.The anti-coccidial index(ACI)in the red control group was only about 126.44,and the ACI in the combined peptide group was 159.79.Compared with red control group,the combined peptide group was significantly higher than that in the red control group.There was significantly reduced in the drip loss and the meat color brightness value(L*),the redness value(a*)was significantly increased,and the yellowness value(b*)was not significantly different in 42nd day.Compared with red control group,the serum ALP activity of broilers at 21st day in ESWP&GP group was significantly reduced,the TP concentration was significantly increased,and the ALB difference was not significant.ALT activity of broilers at 42nd day was significantly reduced,and ALP and TP were not significantly different.The activity of antioxidative enzymes(CAT,SOD,GSH-Px)in the serum of broilers in ESWP&GP group were significantly increased,and the MDA content was significantly reduced.In ESWP&GP group,the length of intestinal villi was significantly longer and the crypt depth became significantly shallower than in red control group.The ratio of villus height to crypt depth was significantly increased.The transformation of blood T and B lymphocytes from broilers in ESWP&GP group was significantly higher than that in red control group.The results showed that polypeptide extract could significantly reduce the oocyst excretion and present a certain anticoccidial effect,and improve the immune function and antioxidant function of broilers infected with Eimeria coccidia,and improve meat quality.To sum up,ESWP and GP have certain antioxidant and immunoregulatory effects in vitro,and polypeptide extracts(ESWP&GP)applied in broiler diets could improve the meat quality of broilers infected with coccidia through nutritional regulation and improve the antioxidant activity,enhance the body's immune regulation function,improve the intestinal mucosal damage,and play a certain relief role in chickens infected with coccidia. |
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