Effects Of Guava Leaf Extract On Growth Performance、serum Antioxidant Activity And Blood Index Of Weaned Piglets

The study contains three parts,including the chemical composition and antioxidant analysis of guava leaves extracts in vitro,the bacteriostatic effect of guava leaves extracts in vitro,and effect of guava leaves extracts on growth performance,serum antioxidant activity and blood physiological index of weaned piglets.The purpose is to explore the feasibility of guava leaves extracts substituting antibiotics used as feed additive,and explore a suitable addition level.In order to study the chemical composition and antioxidant effect of different polarity extracts of guava leaves in vitro,the contents of total flavonoids and phenols and the main chemical constituents in the extracts of guava leaves were determined by UV-Vis spectrophotometry and GC-MS.The antioxidant effect in vitro of guava leaves extracts were determined by DPPH、ABTS and FRAP.The results showed that the highest content of total phenol was n-butanol extract from guava leaves,the content of which was 215.55mg/g(P>0.05),and the highest content of total flavonoids was ethyl acetate extract from guava leaves,the content of which was 42.59mg/g(P>0.05).The results showed that the extracts of guava leaves contained phenols,volatile oils,organic acids,sugars,flavonoids and other classes of compounds,the most important compounds in petroleum ether and ethyl acetate extracts of guava leaves were volatile oil,the relative contents were 85.99%and 79.61%,the most abundant compounds in n-butanol extract were phenols,the relative content of which was 48.49%,The main phenolic component is pyrogallol.The antioxidant activity of ethanol,ethyl acetate and n-butanol extract from guava leaves was higher than that of vitamin C(P>0.05),while the antioxidant activity of petroleum ether extract was the weakest.In conclusion:the extracts of different polarity of guava leaves have antioxidant effect,and the higher content of total phenol in the extract is,the better antioxidant effect is.In order to study the bacteriostatic effect of different polarity extracts of guava leaves in vitro,the bacteriostatic effects of different polarity extracts of guava leaves on porcine Escherichia coli and Staphylococcus aureus were determined by tube doubling dilution method and inhibition circle perforation method.The results showed that the bacteriostatic effect of different polarity extracts of guava leaves on Staphylococcus aureus was better than that on Escherichia coli,and petroleum ether extract had the best bacteriostasis effect on Staphylococcus aureus.In Conclusion:different polarity extracts of guava leaf have bacteriostatic effect,and petroleum ether extract of guava leaf has the best bacteriostasis effect on swine Staphylococcus aureus.In order to explore the effect of guava leaf extract on growth performance,serum antioxidant capacity and blood parameters of weaned piglets.In this experiment,a total of thirty-six weaned piglets at 21-days of age were randomly divided into six groups with three replicates in each group and two pigs per replicat.Piglets were challenged with Escherichia coli(1×10g cell per head)during adaptation period.Basal diet for BC and NC groups,PC group added 50mg/kg quinolone to basal diet,group T50,T100 and T200 added 50 mg/kg,100 mg/kg and 200mg/kg of guava leaf extract in basal diet,respectively.All piglets except BC group were orally challenged with Escherichia coli,and the experiment period was 28 days.The results showed that the diarrhea rate of piglets in each test group decreased with the increase of extract concentration of guava leaf.Compared with the control group,supplementation the 50 mg/kg extract of guava leaf significantly increased the activity of glutathione peroxidase(GSH-PX)(P<0.05),decreased the content of malondialdehyde(MDA)(P>0.05),increased the contents of platelet number(PLT),total protein(TP)and glycerin trilaurate(TG)(P<0.05),and decreased the activity of alanine aminotransferase(ALT),aspartate aminotransferase(AST)and the content of cholesterol(CHOL)in serum.Compared with BC group and NC group,the total antioxidant capacity(T-AOC)in PC,T50,T100 and T200 group was significantly increased(P<0.05).In conclusion,the extract of guava leaf can reduce diarrhea rate and improve antioxidant ability of piglets.Meanwhile,it can improve the immunity of piglets,improve liver function and promote the protein synthesis and metabolism,and the effect is better than that of quallone.Therefore,it is concluded that guava leaf extract has the potential as a green feed additive to replace antibiotics and the appropriate addition level of guava leaf extract is 50 mg/kg in piglets diet.