Effects Of Fish Meal From Different Sources On Growth,serum Indexes And Intestinal Health Of Monopterus Albus

An 8-week feeding experiment was conducted to evaluate the effects of fish meal from different source on the growth performance,serum indexes and intestinal health of Monopterus albus[initial body weight(55.00±0.10)g].Five experimental diets consisted of fish meal from different source,corresponding to dietary inclusion levels of Peruvian red fish meal(PRF),New Zealand white fish meal(NZWF),North Pacific white fish meal(NPWF),Russian white fish meal(RWF),Danish white fish meal(DWF).The breeding experiment was carried out in a pond cage(1.5 m×2.0 m×1.5 m)for 8 weeks.After the breeding experiment,the physical indexes of Monopterus albus were measured and the contents of the intestine were collected.After fasting for 24 hours,the blood and intestinal slices were taken.The results are as follows:1、Effects of fish meal from different sources on growth and serum indexes of Monopterus albusFish meal from different sources had no significant effect on the SR,HSI and VSI(P>0.05).Compared with red fish meal group,white fish meal group can improve the W_t,WGR and CF,and reduce the FCR.Compared with PRF,RWF and DWF group,the WGR and CF in NZWF and NPWF group increased significantly(P<0.05),FCR and WGC in NZWF group and NPWF group decreased significantly(P<0.05).There was no significant difference in the contents of water,crude protein and crude ash from different sources(P>0.05).The crude fat in red fish meal group was higher than that in white fish meal group,but the difference was not significant(P>0.05).Fish meal from different sources had no significant effect on the contents of serum C3 and C4(P>0.05).Compared with PRF group,the contents of serum HDL-C,BUN,GLU,Ig M and Ig A in NZWF,NPWF and DWF group increased significantly(P<0.05),while the contents of TG,TC and LDL-C decreased significantly(P<0.05).Compared with PRF group,the content of Ig A in RWF group increased significantly(P<0.05),and TG and TC decreased significantly(P<0.05).The content of serum Ig M in NZWF,NPWF and DWF group was significantly higher than that in RWF group(P<0.05).2、Effects of fish meal from different sources on intestinal tissue structure and intestinal immune barrier related gene expression in Monopterus albusCompared with red fish meal group,the height of intestinal villi in white fish meal group was significantly higher(P<0.05),and the number of intestinal villi goblet cells in NZWF,NPWF and DWF group was significantly higher than that in PRF group(P<0.05).Compared with PRF group,the NZWF,NPWF and DWF groups significantly downregulated the IL-1β,IL-6,IL-8 and IL-12βm RNA levels in the intestine(P<0.05),upregulated the IL-10,TGF-β1 m RNA levels,but the difference was not significant(P>0.05).Compared with PRF group,NZWF,NPWF group significantly downregulated NF-κB m RNA levels(P<0.05),NPWF,RWF and DWF groups significantly downregulated TLR-7m RNA levels(P<0.05).3、Effects of fish meal from different sources on intestinal flora of Monopterus albusThe samples of each group were statistically analyzed and the petal diagram was constructed.It was found that the total number of out in each group was 76,and the unique number of out in PRF,NPWF,NZWF,RWF and DWF group were 305,60,82,79 and 123respectively.There was no significant difference in good’s coverage,observed species,Shannon,Chao1,Simpson and PD whole tree index among the groups.The composition similarity intestinal flora in PRF group with NPWF and NZWF group was lower than that in PRF group with RWF and DWF group.The results showed that the intestinal flora was mainly composed of Firmicutes,Fusobacteriota,Proteobacteria and Bacteroidota at the phylum level.The relative abundance of Firmicutes in the intestine in NZWF,NPWF and RWF groups was higher than that in PRF and DWF groups,and the relative abundance of Fusobacteriota was lower than that in PRF and DWF groups.The relative abundance of intestinal Proteobacteria in NPWF group was higher than that in other groups,and the relative abundance of intestinal Bacteroidota in RWF group was higher than that in other groups.The results showed that the intestinal flora was mainly composed of Cetobacterium,Clostridium＿sensu＿stricto＿1 and Plesiomonas at the genus level.The relative abundance of Cetobacterium in PRF and DWF group was higher than that in NZWF,NPWF and RWF group.The relative abundance of Clostridium＿sensu＿stricto＿1 in the intestine flora in NZWF and NPWF group was higher than that in other groups.Conclusion:(1)compared with red fish meal,white fish meal can significantly increase the weight gain rate,reduce the feed coefficient,reduce the content of body crude lipid.At the same time,it can increase the content of serum immune index and enhance the non-specific immune ability of the body;(2)The mechanism of white fish meal to improve the nonspecific immune indexes may be the down regulation of TLRs/NF-κB expression of signaling pathway,thereby down regulating pro-inflammatory cytokines and increasing gene expression of anti-inflammatory cytokines;(3)In addition,white fish meal feed can improve the intestinal tissue structure and enhance the intestinal digestion ability.At the same time,improve the composition of flora and enhance the species abundance of Firmicutes and Proteobacteria.Under the experimental conditions,the effects of New Zealand white fish meal and North Pacific white fish meal were the better.