Evaluation of a single-cell protein as a dietary fish meal substitute for whiteleg shrimp Litopenaeus vannamei

A 9-week feeding trial was conducted to evaluate the optimum dietary level of PROTIDE (PRO), a single-cell protein obtained from the bacteria Corynebacterium ammoniagenes, as a substitute for fish meal in the diet of whiteleg shrimp Litopenaeus vannamei. Five diets were formulated that replaced fish meal at 0% (PRO0), 10% (PRO2), 20% (PRO4), 30% (PRO6) and 40% (PRO8). Fifty shrimp averaging 0.15 +/- 0.02g (mean +/- SD) body weight were randomly distributed between 20 experimental tanks and fed one of the five experimental diets. At the end of the experiment, final weight, weight gain, specific growth rate and feed conversion ratio of shrimp fed PRO0 and PRO2 diets were significantly improved compared to those fed PRO6 and PRO8 diets (P<0.05). The proximate composition of muscle and the whole body indicated an increase in crude protein content with an increase in dietary PRO level. These results suggest that, for whiteleg shrimp, the optimum dietary level of PRO when used as a replacement for fish meal should be greater than 10% (PRO2) but less than 20% (PRO4) without any additional dietary amino acid supplementation.