Analysis of changes in intestinal structure and microbial composition in Elentheronema tetradactylum juvenile at different days of age

In order to explore the intestinal development and microbial communities of Elentheronema tetradactylum juvenile, and to provide a scientific basis for its healthy breeding and feeding management, we investigated the growth performance, intestinal structure and gut microbiota of the juveniles at different days of age (37, 44, 58, 72, 86, 114). The results show that there were significant differences in the growth performance among different days of age (p<0.05). As the age of the juveniles increased, the length and width of the villi, the thickness of the myenteric layer, and the number of cup-shaped cells increased gradually and became more complete. On Day 58, the morphological structure of the intestinal tract was relatively well-developed. A total of 40 microbial phylum and 521 microbial genus were identified in the intestine. Proteobacteria, Actinobacteria and Firmicutes were the dominant phylum, which accounted for 78.69% of the total intestinal microbiota. On the genus level, there were significant differences in the relative abundances of microbial genus at different days of age (p<0.05), with large variations in abundance. Pearson correlation analysis reveals that the villus length, width, and muscular thickness were negatively correlated with Gemmobacter and Defluviimonas (p<0.05), but positively correlated with Burkholderia, Vibrio and Ralstonia (p<0.05). The relative abundances of pathogenic genus (Ralstonia, Vibrio) exhibited an increase after feeding with the pellet feed. It is not advisable to feed E. tetradactylum juvenile with an excessive amount of pellet feed at the early stage, and it should enhance the water quality monitoring and pathogen prevention during the feed transition period.