Effects of bioflocs on dietary protein requirement in juvenile whiteleg Shrimp, Litopenaeus vannamei

A feeding trial was carried out to determine the effects of bioflocs on dietary protein requirement in juvenile whiteleg shrimp, Litopenaeus vannamei. Four bioflocs treatments (BFT) and one control group were managed: BFT fed diets 25% of crude protein (CP) (BFT-25%), 30% CP (BFT-30%), 35% CP (BFT-35%) and 40% CP (BFT-40%), and clear water control without bioflocs fed with 40% CP (CW-40%). Triplicate groups of shrimp (initial body weight, 1.3 g) were fed one of the test diets at a ratio of 7% body weight daily for 8 weeks. At the end of the feeding trial, significantly (P < 0.05) higher weight gain and specific growth rate were obtained in shrimp fed BFT-35% and BFT-40% compared to BFT-25% and BFT-30%. Shrimp fed BFT-35% exhibited the lowest feed conversion ratio. Significantly higher muscle nucleic acid indices were also recorded such as DNA content in BFT-30%, RNA content in BFT-35% and RNA/DNA ratio than that of shrimp fed control. Total protein level in the haemolymph of shrimp fed BFT-40% was significantly higher than those of shrimp fed BFT-25% and BFT-30%. Therefore, the present results demonstrated that, when L. vannamei juveniles were reared in bioflocs- based tanks, dietary protein level could be reduced from 40% to 35% without any adverse effect on shrimp growth performance, body composition and haemolymph characteristics. [Correction added on 20 May 2015, after first online publication: sentence modified to clarify the reduction in dietary protein level.].