Effects of Dietary Folic Acid Supplementation on Sex Differences in Oriental River Prawn, Macrobrachium nipponense

Abstract

To better understand the sex differences in the utilization of folic acid for male and female prawns, Macrobrachium nipponense, three experimental diets with graded folic acid contents (A: 1.22 mg/kg, B: 5.44 mg/kg, and C: 10.09 mg/kg) were provided to prawns for 8 weeks. The experimental study demonstrated that prawns fed diets containing 1.22 mg/kg showed the best values on body weight gain (BWG), specific growth rate (SGR), and individual weight for both males and females. Male prawns fed above 1.22 mg/kg of dietary folic acid significantly decreased the crude protein contents in their bodies (p < 0.05), while no significant differences were observed in females among all treatments (p > 0.05). The protease activity of the hepatopancreas in females was significantly (p < 0.05) improved by a dietary level of 10.09 mg/kg of folic acid. However, the opposite trend was observed in males, with the highest protease activity observed at a dietary level of 1.22 mg/kg folic acid. Increasing dietary folic acid levels did not suppress early maturation but led to an increase in the fecundity of females. Furthermore, prawns fed with 10.09 mg/kg of folic acid exhibited improved tolerance against thermal stress in both males and females. Transcriptome analysis revealed that during thermal stress, the “Oxidative phosphorylation” and “Pantothenate and CoA biosynthesis” signaling pathways were significantly enriched in females, and the “Fatty acid biosynthesis” signaling pathway was significantly enriched in males. The results of this study preliminarily evaluate the differences between male and female M. nipponense in response to different dietary folic acid levels and are helpful in promoting the health and growth of aquaculture production of this species.