| Antimicrobial peptides(AMPS)have been widely used in livestock and poultry breeding due to their antiviral,antitumor,immunomodulatory and antioxidant functions.The research results are mostly concentrated in poultry,pigs,rabbits and aquatic animals,while the research on the effect of AMPS on the immune and antioxidant functions of ruminants is less.Therefore,this experiment analyzed and compared the differences of serum immunoglobulin,cytokines,T lymphocyte subsets and antioxidant indexes after adding compound antimicrobial peptide(PBD-m I:LUC-n=1:1)and tumefacitin in the feed of high precision finishing Capra hircus,in order to explore the effects of compound antimicrobial peptides on some serum immune and antioxidant indexes of high precision finishing Capra hircus,and to provide theoretical basis for the application of compound antimicrobial peptides in ruminant feed.Twenty-five healthy 6-month-old male Capra hircus with similar body weight(23.69±0.42 kg)were randomly divided into 5 groups.After a week of adapting to feeding,the formal test begins.Group I is a normal concentrate control group;groupⅡis a high-concentration control group,groupⅢwas the high-precision antimicrobial peptide group,and the compound antimicrobial peptide2g·d-~1·goat-~1 was added on the basis of high-precision diet;groupⅣwas the high-precision rumen group,and the rumen element 50mg·kg-~1·d-~1 was added on the basis of high-precision diet;groupⅤwas the high-precision mixture group,and the compound antimicrobial peptide 2g·d-~1·goat-~1 and the rumen element 50mg·kg-~1·d-~1 were added on the basis of high-precision diet The experimental period was 60 days,which was divided into three stages,with 20 days in each stage.Except for the normal control group,the ratio of concentrate to roughage in each stage was 40:60,and the ratio of concentrate to roughage in the other four groups changed at 60:40,70:30 and 80:20,respectively.Blood samples were collected from all the Capra hircus in each group before morning feeding on the 0d,20d,40d and 60d during the experimental period.Using ELISA,visible light method,DTNB color method,xanthine oxidase method and other techniques to detect the content of immunoglobulin Ig A,Ig M,Ig G in serum;cytokines IL-1β,IL-2,IL-6,IL-12,TNF-α,IFN-γ,IL-4,IL-10 content;distribution of T lymphocyte subsets;antioxidant index SOD,CAT,T-AOC and GSH-Px activity.Test results:(1)High-concentrate feeding increased the levels of immunoglobulin Ig A,Ig M and Ig G in fattened Capra hircus serum but the effect was not significant(P>0.05).The addition of compound antimicrobial peptides alone or a combination of antimicrobial peptides and oncolin could significantly increase the contents of serum immunoglobulin Ig A(significant on the 20th,40th and 60th day)and Ig M(significant on the 40th day),and also increase the content of serum Ig G but not significantly(P>0.05).Compared with the two groups,the effect of adding compound antimicrobial peptides alone was better.However,the addition of rumen in the high-precision diet had no significant effect on the serum immunoglobulin content in finishing goats(P>0.05).Serum immunoglobulin Ig A,Ig M,Ig G content of goats in the four high-concentration groups decreased at the 60th day compared to the 40th day.(2)Compared with the normal control group,the contents of pro-inflammatory factors IL-1β,IL-2,IL-6,IL-12,TNF-α,IFN-γand anti-inflammatory factors IL-4 and IL-10 in the high concentrate control group were higher than those in the normal control group,but the effect was not significant(P>0.05).On the other hand,the addition of compound antimicrobial peptides alone or a mixture of antimicrobial peptides and oncolin could significantly increase the contents of pro-inflammatory and anti-inflammatory factors in the serum of high-precision finishing goats,and reached a significant effect on the 40th day(P<0.05).The effect of adding compound antimicrobial peptides alone was better than that of the mixed group.However,the addition of rumen in the high-precision diet had no significant effect on the serum cytokine content in fattened Capra hircus(P>0.05).Serum cytokine content of fattened Capra hircus in the four high-concentration groups decreased at the 60th day compared to the 40th day.(3)High concentrate diet significantly increased the number of CD3~+in serum of goats on the 20th and 40th day,(P<0.01),the ratio of CD8~+cells was significantly increased on the 40th day(P<0.05),and the ratio of CD4~+/CD8~+in serum of fattened Capra hircus was significantly increased by high concentrate diet(P<0.01).The addition of compound antimicrobial peptides to high concentrate diet could significantly increase the number of CD3~+,the ratio of T cell subsets of CD4~+and CD8~+and the ratio of CD4~+/CD8~+(P<0.05or P<0.01)in serum.The mixed addition could also significantly increase the number of CD3~+and the ratio of T cell subsets of CD4~+and CD8~+in goats(P<0.05),but the effect was not as good as that of compound antimicrobial peptides alone.The addition of ruminin alone had no significant effect on the distribution of T lymphocyte subsets in peripheral blood of high precision fattened Capra hircus(P>0.05).The number of CD3~+,the ratio of CD4~+and CD8~+and the ratio of CD4~+/CD8~+in the serum of the four high concentrate groups on the 60th day were lower than those on the 40th day.(4)Feeding high concentrate diet decreased the activity of serum antioxidant indexes such as SOD,CAT,GSH-Px and T-AOC.Adding compound antimicrobial peptides could increase the activity of antioxidant indexes and enhance the antioxidant function of fattened Capra hircus,and the difference was the most significant on the 40th day(P<0.05or P<0.01).The addition of ruminin had a certain effect on the antioxidation indexes in serum,but the effect was not as good as that of antimicrobial peptides.And there was no significant difference between the effect of the combination of the two and the addition of antimicrobial peptides alone on the antioxidant capacity of fattened Capra hircus.ConclusionHigh concentrate diet supplemented with compound antimicrobial peptides could increase the contents of serum immunoglobulin Ig A,Ig M and Ig G,promote the secretion of pro-inflammatory factors IL-1β,IL-2,IL-6,IL-12,TNF-α,IFN-γand anti-inflammatory factors IL-4 and IL-10,improve the distribution of T lymphocyte subsets in peripheral blood and increase the activities of serum antioxidant indexes such as SOD,CAT,GSH-Px and T-AOC in fattened Capra hircus.The results showed that the addition of compound antimicrobial peptides could improve the immune and antioxidant ability of high-precision fattened Capra hircus. |
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