Changes revealed by histology, physiology, enteric microbiota, and transcriptome after ovarian ripening of shrimp, Litopenaeus vannamei, through using fresh baits support the innovation of artificial ripening of shrimps

Litopenaeus vannamei is the most economically important aquaculture shrimp species, and feeding normal feeds cannot ripen the ovaries of female shrimp during the farming process. In production practice, eyestalk ablation (ESA) in combination with the feeding of fresh baits is widely used to accelerate ovarian maturation. However, this method is considered cruel and results in some issues such as reduced parental immunity and low egg quality. Recently, we found that ovary maturation can also be rapidly induced by using only fresh baits, but the mechanism behind this is still unclear. In this study, we integrated the results of histological assays, biochemical analysis, ovarian transcriptome and intestinal microbiota to reveal that fresh baits can promote ovarian maturation by modulating ovarian and hepatopancreatic lipid metabolism, promoting vitamin K metabolism, the tricarboxylic acid cycle, and the proliferation of beneficial bacteria, as well as increasing vitamin B metabolism in the ovary. The present study is of great significance for the development of functional compound feeds for parent shrimps and for developing non-ESA methods for artificial gonad ripening of shrimps. • Fresh baits can completely ripen the ovaries of shrimp, Litopenaeus vannamei . • Fresh baits promote positive changes of biochemical indexes of the hepatopancreas. • Fresh baits up-regulate the pathways related to lipid metabolism and vitamin metabolism in the ovary. • Some microbial groups responsible for the metabolisms related to ovarian mature were enriched after feeding fresh baits.