Effect Of Dietary Sodium Butyrate On Growth, Immune And Intestinal Health In Rice Filed Eel (Monopterus Albus)

The study was conducted to study the effect of sodium butyrate inclusion in feed of rice filed eel (Monopterus albus) on the growth performance, partial blood parameters, intestinal mucosal morphology, glucose transport and the structure of intestinal flor. Two series of diets were formulated to contain the similar amounts of crude protein and crude lipid. Fish meal and soybean meal were used as the primary protein source, and fish oil as the lipid source in the diet. The high fish meal diet series contained 42% fish meal and 18% soybean meal. The low fish meal diet series contained 32% fish meal and 33% soybean meal, where soybean meal replaced 23.81% of fish meal. To each of these diet series, sodium butyrate was supplemented at 0,250,500,1000 mg·kg-1 dry diet. Each group had 3 replicates and each replicate had 100 fish. The experiment lasted for 8 weeks.1. Growth and immune responseThe results showed that the inclusion of sodium butyrate in low fish meal diet significantly improved WG, spleen index, the activities of SOD and LZM, TP, decreased FCR, the content of MDA, BUN and GLU. Inclusion of sodium butyrate in high fish meal diet significantly improved LZM activity, decreased GLU content. No significant differences were observed on other parameters. In conclusion, sodium butyrate could improve growth performance, feed conversion efficiency, and immune response of M. albus when fish meal was replaced with soybean meal.2. Intestinal mucosal structure and genes expressionThe inclusion of sodium butyrate in low fish meal diet repaired the intestinal mucosal structure, improved the value of villus height/crypt depth, decreased the crypt depth, and increased the expression of genes related to intestinal cell proliferation, including ornithine decarboxylase (ODC) and proliferating cell nuclear antigen (PCNA), genes related to glucose transport, including SGLT1 and GLUT2. No differents were observed on the inclusion of sodium butyrate in high fish meal diet.3. Bacterial community structure in the intestineThe bacterial community structure in the intestinal content of M.albus fed diets with different levels of sodium butyrate were investigated using a culture-independent methord of 16S rDNA PCR-DGGE fingerprinting, and the main advantages of the gel bands were cloned and sequenced. By the analysis of PCR-DGGE fingerprint, we found that the sodium butyrate inclusion in low fish meal diet improved the band amount and bacterial diversity. The similarity coefficient of DGGE fingerprint of the low fish meal diet with and without sodium butyrate was 48.5%?59.2%, and that of the high fish meal diet with and without sodium butyrate was 43.3%?58.2%. The major bands of PCR-DGGE fingerprinting were recovered, cloned and sequenced,26 sequences were obtained. By NCBI database homology analysis results showed that bacterial communities from M.albus contents mainly were Bacillus Cohn, Rhodopseudomonas, Acinetobacter and uncultured bacterial.