DIETARY SUPPLEMENTATION WITH MICROBIAL BIOMASS (NOVACQ™) IMPROVES WHITELEG SHRIMP GROWTH
The whiteleg shrimp (Litopenaeus vannamei) is the most widely cultivated penaeid shrimp in the world, and is a euryhaline species that can tolerate a wide range of salinities (0.5-45 ppt). As a result, i nland aquaculture of shrimp in low salinity (< 5 ppt ) waters is popular in many regions worldwide. In this study, we evaluated the effect of a microbial biomass (NovacoTM) on shrimp growth . Five experimental diets were formulated, including 20% fishmeal and 0, 5 or 10 % NovacoTM , or 15% fishmeal and 5 or 10 % NovacoTM. There were 4 thanks per treatment group with 20 juvenile whiteleg shrimp (initial body weight of ~0.5 g ) per tank (50 L water , 3-5 ppt salinity) . Shrimp were assigned randomly into one of the five treatment groups, and fed their respective diets to satiety twice per day. The feeding trial was conducted for 8 weeks. The results indicated that the survival of shrimp at the end of experiment did not differ among treatment groups (P = 0.96) . Shrimp fed t he 5% of NovacoTM diet exhibited improve ments in growth performance (+ 15.8 % , P = 0.01 ) and feed efficiency (+1 8.6 % , P = 0.04 ) when diets contained 20% fishmeal. The weight gain of shrimp fed the 15% fishmeal diet and 5% or 10% NovacoTM did not differ ( P = 0.95 or 0.80, respectively ) from that for shrimp fed the 20 % fishmeal diet without NovacoTM . Interestingly, the concentrations of some amino acids (including taurine and glutamine) in hemolymph were greater (P < 0.05) in shrimp fed the 5% NovacoTM diet, compared with the control diet. In conclusion, the appropriate supplementation with microbial biomass (NovacoTM ) to practical feeds enhanced the bioavailability of some dietary amino acids, growth performance, and feed efficiency in whiteleg shrimp raised under a low salinity water environment. We suggest that addition of 5 % NovacoTM to practical diets for whiteleg shrimp can reduce the inclusion level of fishmeal in the diet from 20 % to 15 % with benefits of decreasing nitrogen excretion and sustaining the environment.
Key Words: Whiteleg shrimp (Litopenaeus vannamei ); Growth ; Microbial biomass.
