Influence of feeding regimes on the digestive enzyme profile and ultrastructure of digestive tract of first feeding catla catla(Hamilton) larvae

Abstract

The present investigation aimed to evaluate the effect of feeding regimes composed of various combinations of live food (LF), artificial food (AF) and mixed food (MF: LF and AF 50% each) on the digestive physiology of first feeding Catla catla (catla) larvae. Larvae (0.92 ± 0.21 mg) were cultured for 30 days under six different feeding regimes of LF, AF, MF, two groups were shifted from LF to AF on day-13 (LF-AF-13) and day-18 (LF-AF-18) and one group from LF to MF on day-12 (LF-MF-13). Significantly (p<0.05) higher survival and average weight of catla were found in MF, LF, and LF-MF-13, respectively compared to others. Chitinase and chitinobiase activities were significantly (p<0.05) higher in LF compared to others. This group was followed by LF-MF-13. Amylase, carboxypeptidase A and B activities were significantly (p<0.05) higher in LF-AF-18, MF and LF-AF-13, respectively compared to others. Total protease, trypsin, chymotrypsin and lipase activities were significantly (p<0.05) higher in LF-MF-13 compared to the other feeding regimes. SDS-PAGE and substrate SDS-PAGE showed the presence of 14 (14.34-97.57 kDa) and 8 (15.26-72.88 kDa) bands, respectively in the digestive tissue extract. The ultrastructure of the digestive tract viz. the height of microvilli, number and size of mitochondria, lipid droplet and goblet cell were influenced by the feeding regime of larvae. LF-MF-13 group was conspicuous by the abundance of mitochondria, nucleus and goblet cell and the absence of lipid droplet. Considering the digestive enzyme profile, survival and growth of larvae, it seems LFMF-13 feeding regime is suitable for catla larvae and co-feeding should be started after 12 days of hatching. © 2014 Meetei LI, et al.