Objective A microencapsulated forage was evaluated to replace live worms for feeding at early development stage of the carnivorous Lanzhou catfish (Silurus lanzhouensis Chen) based on the resulting larval weaning, juvenile growth, and enzyme activities in digestive tracts.
Method Two experiments were conducted with the microencapsulated forage (MF) introduced to the fish at different ages. In the first experiment, 3 groups of randomly divided catfish larvae were fed with either MF (WW), a combination of MF and live worms (WL) or live preys (LL). Larval survive rate and growth in 30 d were monitored following the feeding. The second experiment examined the effects of WW versus minced meat (RR) for feed on the growth and metabolism of the juveniles for 115 d.
Result (1) Domesticating the fish in the WW group was significantly the least effective among all. However, the survival rate of (94.3±0.9)% on the fish fed with WW was significantly higher than the other two forages (P ＜0.05). And the body weight increase of the catfish in the WL group were the fastest (P ＜0.05). Significant differences in SGR and AGR of LL group were observed compared with the other two treatments (P ＜0.05) . (2) MF appeared to significantly promote the growth from larval to juvenile stage of the catfish. There were significant differences on the performances by the different forages (P ＜0.05). Except for no difference between 2 treatments for the enzymatic activities of pepsin in the midgut, hindgut and stomach, the enzymatic activities of lipase, amylase, and pepsin in the pancreas, stomach, foregut, midgut, and hindgut of the fish tended to be higher in the WW group fed on WF than on RR.
Conclusion MF significantly improved the growth and maintain a relatively uniform size of catfish at early development stages. The use of MF for catfish aquaculture was highly recommended.
DownLoad: