Study On Enhancement Of Immunity Of Sichuan White Geese With Avian Influenza Vaccine By Hermetia Illucens Larvae Meal

Hermetia illucens is an insect of the diptera family.It has the obvious advantages of low feeding cost,fast breeding speed and high output.Because of its rich amino acids,antimicrobial peptides,chitin and other bioactive substances,Hermetia illucens has become one of the most potential sources of high quality insect protein.Many studies have confirmed that Hermetia illucens larvae meal(HILM)can improve the growth performance of livestock and poultry,enhance the body immunity and improve the intestinal flora.However,whether the addition of HILM to the diet enhances the immune effect of the vaccine has not been proven.In this study,Sichuan white geese were selected as the research object to explore the effects of dietary HILM on humoral immunity,cellular immunity,intestinal mucosal immunity and intestinal flora after inoculation with avian influenza vaccine.The purpose of this study is to provide theoretical basis for further development of immune enhancers for healthy poultry breeding.The main contents and results of this study are as follows:1.In order to explore the optimal dosage of HILM,64 one-day-old goslings were randomly divided into four groups.The control group was fed with the basic diet,and the experimental groups were fed with 1%,2% and 4% HILM,respectively.Feed intake,average daily gain,immune organ index,serum biochemical indicators,avian influenza antibody titers and avian influenza specific antibody levels were recorded.The results showed that compared with the control group,diet supplemented with 1% HILM significantly increased the content of ADG and serum GLB(P<0.05),and decreased the feed/gain(P>0.05).Adding 2% and 4% HILM significantly increased the serum TCHO content(P<0.05).The addition of 1% HILM significantly increased the thymus index and spleen index(P<0.05),and significantly increased the titers of antibodies against avian influenza H5-R14(P<0.01)and H7-R4(P<0.05)at 3 weeks after one dose of vaccination.The serum H5-R13 antibody titer at 1 week after second immunization was significantly increased(P<0.01).At the same time,the level of avian influenza specific antibody in 1% HILM group was higher than that in the other two groups at each time point after vaccination,but the difference was not statistically significant(P>0.05).These results suggest that feed containing 1% HILM can improve the performance of Sichuan white geese,and it has the best effect on enhancing the immunity against avian influenza vaccine.Therefore,the optimal dosage of HILM was determined as 1%.2.In order to explore the effects of 1% HILM supplementation on the expression of immune factors and spleen genes of Sichuan white geese.In this study,ELISA and q-PCR were used to detect the expression of serum immune factors and spleen related genes.The results showed that the supplementation of 1% HILM significantly increased serum Ig G,Ig G1,Ig G2 a,Ig G3 antibody levels and serum complement C3concentration(P<0.05).And significantly increased the expression of IL-6 gene in spleen(P<0.05)and CD4 gene expression was significantly increased(P<0.01).The results indicated that 1% HILM in the diet could improve the immune antibody level of avian influenza in Sichuan white geese.3.In order to explore the effects of 1% HILM supplementation on intestinal mucosal barrier and mucosal immune function of Sichuan White geese.Fixed tissues of duodenum,jejunum and ileum were used to make paraffin sections,and the intestinal morphology and structure were observed by HE staining.The expression level of barrier gene in jejunum tissue was determined by q RT-PCR.The results showed that supplementation of 1% HILM can significantly increase villus height in duodenum,jejunum and ileum of Sichuan white geese(P<0.05)and increased the ratio of villus height to crypt depth(P<0.05);And can significantly increase the secretory immunoglobulin A(SIg A)content in jejunum and jejunum Occludin gene expression level(P<0.05).The results indicated that HILM could enhance the intestinal mucosal physical barrier and enhance the intestinal mucosal immune function of Sichuan white geese.4.In order to explore the effect of 1% HILM supplementation on intestinal flora of Sichuan white geese,fresh cecum contents were collected for 16 s sequencing analysis.The results showed that 1% HILM could significantly increase the microflora OUT(P<0.05),chao1 index,Shannon index and Simpson index all showed an increasing trend,but the statistical difference was not significant(P>0.05);And the contents of Campilobacterota,Barnesiellaceae and Barnesiella were significantly reduced(P<0.05),and significantly increased the Lactobacillaceae content(P<0.05).The results indicate that HILM may improve intestinal health and enhance immune function by regulating intestinal flora structure.In conclusion,dietary 1% HILM can improve the performance of Sichuan white geese,reduce the ratio of feed to gain,promote serum immune function,improve the immune effect of avian influenza vaccine,improve intestinal barrier function and intestinal flora structure.