Response of Eel fingerling on Recombinant Giant Grouper Growth Hormone by immersion and oral administration

Abstract

This study was aimed to determine an appropriate administration method and observe the response of eel fingerling on recombinant giant grouper growth hormone (rElGH). First study aimed to determine the immersion dose of rElGH to increase growth of eel juvenile (glass eel). After shock salinity treatment (NaCl 3% for 2 min), glass eel were immersed in water containing 0.9% NaCl, 0.01% bovine serum albumin, and different of dose of rElGH (0, 0.12, 1.2, 12 and 120 mg/L). The results showed that higher in growth body weight was obtained in treatment 12 mg/L (101.2±0.8), by increment of about 37.4% higher compared to that of control (72.93±1.8). Second study was aimed to determine the dose of rElGH mixed in artificial diet to increase growth of eel elver. HP55-coated rElGH was mixed to diet at different doses (0, 0.3, 3, and 30 mg/kg). Elver was fed on diet containing rElGH twice daily, 6% fish biomass. The result showed that higher in growth body weight was obtained in treatment 30 mg/kg (60.18±1.38), by increment of about 65.7% compared to control (36.32±0.97). Third study was aimed to compared of three administration method, namely immersion, oral, and combination of immersion and oral. The dosage of rElGH by immersion (12 mg/L) and oral administration (30 mg/kg feed) was obtained in previous study. Fish were maintained in 23-L glass aquaria for 120 days, at density of 45 fish per aquarium. The results showed that higher (P<0.05) biomass of harvest (73.68±2.07 g) was obtained in immersion and oral combination treatment, by increment of about 102.9% compared to control (36.32±0.97 g). Administration of rElGH also improved protein and lipid retentions by 142.5%, and 720% compared to that of control, respectively (P<0.05). In addition, rElGH treatment increased appetite, while artificial feed conversion ratio (4.75) was lower (P<0.05) by 55.15% compared to that of control (7.37). Combination of rElGH immersion and oral administrations also increased hepatosomatic index, reduced ammonia excretion and increased insuline-like growth factor-1/IGF-1 gene expression. Thus, rElGH administration via immersion and oral was a proper method to improve performance of eel fingerling, and application of rElGH can be useful to increase aquaculture production.