Optimization of weaning age for striped murrel (Channa striata) based on expression and activity of proteases

The pattern of gene expression and the activity of three proteases - trypsin, chymotrypsin, and pepsin - were investigated from yolk sac stage to 35 days post hatching (dph) in larvae and juveniles of striped murrel (Channa striata), a high-value fish species with a great potential for aquaculture. The mRNA expression level of trypsin increased from 3 dph onwards and concurrently with absorption of the yolk sac, peaking at 12 dph and 25 dph (p < 0.05). Chymotrypsin expression peaked at 21 dph. In pepsin, mRNA levels were not detectable from hatching to 3 dph but increased significantly at 25 dph (p < 0.05). Maximum specific activity of trypsin was observed at 18 dph, while chymotrypsin showed significantly higher (p<0.05) activity at 21 dph. Specific activity of pepsin increased from 18 dph onwards and peaked at 30 dph. These patterns suggest that larvae/juveniles of C. striata are best weaned between 18 dph and 25 dph to coincide with functional development of the exocrine pancreas and stomach.

Automated summary

The pattern of gene expression and the activity of three proteases were investigated in larvae and juveniles of striped murrel. The study found that the expression levels and activities of trypsin, chymotrypsin, and pepsin varied during the growth stages, suggesting the optimal weaning period for larvae/juveniles of C. striata.