Effects of the apple mangrove (Sonneratia caseolaris) on growth, nutrient utilization and digestive enzyme activities of the black tiger Penaeus monodon postlarvae

A growth trial was conducted to evaluate the twig extracts of the apple mangrove (Sonneratia caseolaris) as growthpromoting agent of Penaeus monodon since it was shown previously to promote immune responses in this species. The twig methanolic extract was incorporated in the basal diet (commercially available shrimp starter feed) and was tested at three feeding frequencies (twice, three and four times daily) for its effects on growth, conversion efficiency and survival against a control treatment (pure basal diet) fed three times daily. Final average body weight (ABW) and length, specific growth rate (SGR) and food conversion ratio (FCR) of shrimps fed the medicated diets were all statistically similar with those fed the control diet with except those fed the medicated diet twice daily which exhibited poorest in all three parameters. Survival of shrimps fed medicated diets were all significantly higher than in those fed the control diet. Activities of amylase, total protease were measured following a 60-day feeding trial of the control diet fed 3 times daily and medicated diets at 2 times, 3 times and 4 times daily. Amylase activity was significantly the highest in shrimps fed medicated diet at 4 times daily while those fed the control and medicated diets at 2 and 3 times daily were statistically similar. Shrimps fed medicated diets at 3 and 4 times daily exhibited significantly the highest and statistically similar protease activities; those fed the control and medicated diets at 2 times daily were inferior and statistically similar