Plant protein-based ingredients usually contain a high amount of phytic acid, which combines with phosphorus to form phytate phosphorus. Shrimp have a low utilization rate of phytate phosphorus because their digestive system does not produce significant amounts of the phytase enzyme; therefore, inorganic phosphorus (IP) is added to the feed to meet the phosphorus requirement. It is crucial to reduce the amount of IP in shrimp feed. Phytase hydrolyzes the phosphate group from phytic acid, lowers the affinity of phytic acid, and makes phytic acid release nutrients to improve the utilization rate of nutrients and reduce environmental pollution. The study was to determine the effects of inositol, phosphorus, and exogenous phytase enzyme on shrimp performance.
A basal diet was formulated to contain 35% crude protein and 8% lipids; phosphorus (P) and phytase levels were adjusted as follows: a positive control (PC) with 1.25% phosphorus (P) and myo-inositol (0.1%); a negative control (NC1) with 1.25% P with none, 1,000, 3,000, and 9,000 FTU of phytase/kg of feed; a second negative control (NC2) with 0.25% P and 0.75% P with none, 1,000, 3,000, and 9,000 FTU of phytase/kg of. A total of 10 diets were made: PC-1.25, NC1-1.25, NC1-1.25+1000, NC1-1.25 +3000, NC1-1.25+9000, NC2-0.25, NC2-0.75, NC2-0.75+1000, NC2-0.75+3000 and NC2-0.75+9000. Each diet consisted of 6 replicates randomly assigned. Shrimp were hand-fed 4 times a day for 47 days. The experiment was conducted in an indoor clear water recirculating system (RAS) in the wet lab at E. W. Shell Fisheries Center (Auburn, AL. USA). At the end of the experiment, data were collected for survival, growth performance, and feed utilization. The whole body, hemolymph, and hepatopancreas were collected for the proximate composition, mineral content, and gene expression for the mineral utilization. Data was analyzed by one-way ANOVA followed by Student-Newman-Keuls Test to determine the difference between means.
The results showed that there was no significant difference in growth performance, survival, and feed conversion ratio among the dietary groups (p > 0.05).
Results of proximate composition, mineral content, hepatopancreas histology and gene related to mineral metabolism will be presented.