Growth characteristics of white prawn <i>Penaeus indicus</i> (Decapoda-Crustacea) under dietary administration of protein hormones

Abstract

The role of protein hormones on the growth characteristics of Penaeus indicus was evaluated with a view to improve the growth potential and production of the shrimp in aquaculture. The hormones, human chorionic gonadotropin (HCG) and L-thyroxine (T4) were incorporated into a prepared supplementary diet. HCG was administered at dosages of 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0 ppm while thyroxine was incorporated at the levels of 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, and 0.07 ppm. Growth, feed utilization, digestive enzymes activity, nucleic acid contents and proximate composition were monitored. All levels of the protein hormones were found to enhance growth. A diet containing 12.5 ppm of HCG or 0.04 ppm of thyroxine brought about the highest growth (12.68 g, 13.3 g respectively). Viscerosomatic index decreased while gonadosomatic index increased due to HCG treatment. Feed conversion efficiency, assimilation efficiency and apparent protein and lipid digestibility showed increase in the hormone supplemented shrimps. In the muscle and hepatopancreas of shrimps under hormone treatments, RNA/DNA ratio were higher than that of the control. The total dry matter and protein contents of the body increased (P<.01) while no significant change was noticed in the lipid content of the hormone treated shrimps. Protein hormones appear to promote growth by stimulating the feed conversion efficiency and nutrient digestibility through enhanced digestive enzymes activity and accelerated protein synthesis in P. indicus (M. Edwards).