Effect of feeding low protein diet and biofloc on growth performance and survival of white Indian shrimp Fenneropenaeus indicus

This experiment was carried out to investigate the effect of feeding low protein diets (BFd_20.13; BFd_22.20 ; BFd_24.32 and BFd_26.44) in the presence of the biofloc on the growth performance and feed utilization of (Fenneropenaeus indicus) in comparison with commercial feed of 35% CP as control. The biofloc was developed in the low protein diet using molasses as a carbon source. 15 juveniles Fenneropenaeus indicus with an average body weight of 0.52 ± 0.03g were stocked in 50L plastic tanks. Low protein diets and the control were tested in three replicates over a 112 days feeding trial. There were no significant differences in final weight between control and experimental diet. Same trend was noted in the SGR, which did not vary significantly between low protein diets and control. However, the utilization of the biofloc by shrimp as a feed source was evident by the significant differences (P<0.05) in FCR between low protein diet and control. There was a significant difference in the shrimp survival (%) (P<0.05) between the low protein diet and the control which ranged between 69.12 % and 84.50 %. The development of biofloc significantly reduced the TAN, nitrate NO₃-N and nitrite NO₂-N levels in the low protein diet tanks. RAPD-PCR were used to study the epidemiology of V. parahaemolyticus responsible for early mortality syndrome (EMS) isolated from the water of culture system. The OPC5 (GATGACCGCC) primer produced bands ranged from 1-8 with sizes from 0.2 - 5.0 kb. The results showed that there were 5 different genetic patterns that were clustered into 3 groups with similarity between 0 to 52%. The high diversity may be due to the biofloc developed in each low protein diet acts as multiple sources of V. parahaemolyticus.

Keywords: Biofloc, low protein feed, shrimp, Fenneropenaeus indicus, growth performance; EMS; V. parahaemolyticus, RAPD-PCR.