Growth Response of Rainbow Trout (Oncorhynchus Mykiss) on Substitution of Shrimp Meal by Different Protien Sources

Abstract

Nepal is rich in cold water resource, commercial rearing of indigenous cold water fish species is not yet in practice. Rainbow trout (Oncorhynchus mykiss) had been introduced in Nepal to expedite the comparative advantage of available suitable climatic conditions. As its farming is expanding, requirement of nutritionally formulated balanced feed has appeared as major bottleneck for sustainable trout production. Till now, shrimp meal (SM) is one of the major ingredients for protein content in trout feed in Nepal. The present work is aimed to develop low cost trout feed replacing SM by alternate locally available ingredients. The four diets were prepared iso-nitrogenous with 44.44 (±0.5) % protein. The feeds were tested in eight weeks experiment trial to determine the efficacy of different feeds on growth and survival of trout fry. Trout fry were kept in twelve cages (0.5m) 3 in a raceway pond with three replications for each diet in random block design. Fry of average 0.31g were stocked in cages in a density of 2000 fry m -2 and fed to satiation 8 to 10 times a day. Feed containing SWP showed significantly higher weight gain (p<0.5) and the highest mortality rate (77%) was observed in synthetic amino acid. Mortality rates of fry fed with feed containing SM, SPM and SMM were found statistically insignificant (p>0.05). Lowest feed conversion ratio (FCR) was 1.33 recorded in feed containing SWP. However, FCR was calculated statistically insignificant (p>0.05) in all four diets. Study concluded silkworm meal could be a proper substitute in rainbow trout feed if it is locally available.