Genetic, nutritional and pathological investigations on the effect of feeding low protein diet and biofloc on growth performance, survival and disease prevention of Indian white shrimp Fenneropenaeus indicus

Abstract

This experiment was carried out to investigate the effect of feeding low protein diets (~20BFd20.13; ~22BFd22.20; ~24BFd24.32, and ~26BFd26.44) 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 present study was based on application of genetic, nutritional and pathological tools. The biofloc was developed in the low protein diet using molasses as a carbon source. Fifty juveniles F. indicus with an average body weight of 0.52 ± 0.03 g were stocked in 50 L plastic tanks. Low protein diets and the control were tested in three replicates over a 112 days feeding trial. There were significant differences in protein, amino acids profile, lipids and fatty acids profile between the control and low diets group in the presence of the biofloc. However, less variation was noticed in the whole body composition (protein, amino acid profile, lipids and fatty acid profiles) of the shrimp between the control and low diets groups in the presence of the biofloc. There were no significant differences in final weight between control and low diets groups. 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 diets and control. There was a significant difference in the shrimp survival (%) (P< 0.05) between the low protein diets and the control which ranged between 86.66 % and 66.66 %, respectively. The development of biofloc significantly reduced the TAN, nitrate NO3-N and nitrite NO2-N levels in the low protein diets tanks. Diagnostic of mortality cases revealed that biofloc can serve as a biosecurity system for shrimp farmimg. RAPD-PCR were used to study the epidemiology of Vibrio parahaemolyticus responsible for early mortality syndrome (EMS) isolated from the water of culture system. The OPC5 (GATGACCGCC) primer produced bands ranged from 1 to 8 with sizes from 0.2–5.0 kb.