Author(s): Rakesh Prasad Bhagat and Sudip Barat

Abstract: Low cost, alternative, and unconventional animal protein in replacement to costly shrimp meals were formulated in the artificial feed and their effect on survival and growth of rainbow trout, Oncorhynchus mykiss (Walbaum) during exogenous feeding in farmer’s raceways were compared. Three feed formulations, two with animal protein of silkworm pupae (Treatment-1) and silkworm moths (Treatment-2) and one with synthetic amino acids of lysine and methionine (Treatment-3) were evaluated through survival and growth along with feed efficiency indicators against shrimp meals acting as control (Treatment-4). All the four diets (three formulated and one control) were fed to the free swimming fries, fries, and fingerlings for 150 days (5 months). There was a significant difference on survival (P<0.01) and growth (P<0.01) of above mentioned stages with all the diets. Survival rate with shrimp meals diet fed stages revealed superiority (P<0.01) over other feed formulations, silkworm pupae diet lesser survival, silkworm moths diet less survival, and synthetic amino acids diet least survival. However, survival due to shrimp meals diet was insignificant (P>0.05) with that of silkworm pupae diet. Growth with silkworm pupae diet fed stages showed superiority (P<0.01) over all the diets and synthetic amino acids diet lowest whereas shrimp meals diet and silkworm moths diet exhibited low and lower growth respectively. However, growth due to silkworm pupae diet was highly significant (P<0.01) with that of shrimp meals diet. So, total feed intake, total protein intake, and feed efficiency indicators of feed efficiency, protein efficiency ratio, absolute growth rate, specific growth rate, and relative growth rate were highest due to silkworm pupae diet, higher due to shrimp meals diet, high due to silkworm moths diet, and lowest due to synthetic amino acids diet. However, condition factor was highest due to silkworm pupae diet, higher due to shrimp meals diet, low due to synthetic amino acids diet and lowest due to silkworm moths diet. Unlike other feed indicators, feed conversion ratio exhibited highest due to synthetic amino acids diet, higher due to silkworm moths diet, low due to shrimp meals diet, and lowest due to silkworm pupae diet. Further, protein productive value percentage resembled crude proteins percentage present in the diets. The highest growth period was observed during May and lowest during December to January in all the diets during 2011 and 2012. Cost analyses revealed silkworm moths diet cheapest with low production cost, silkworm pupae diet cheaper with lowest, synthetic amino acids diet cheap with highest, and shrimp meals diet costly with high production cost. Results also indicated that natural and animal protein of silkworm pupae diet, shrimp meals diet, and silkworm moths diet was superior to synthetic amino acids diet. The results finally confirmed that cost effective silkworm pupae diet could be used as better alternative to completely replaced shrimp meals diet without compromising survival and growth.

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