RECOMBINANT GROWTH HORMONE APLICATION FOR GROWTH AND IMMUNITY IMPROVEMENT OF HUMPBACK GROUPER CULTURE
Humpback grouper Cromileptes altivelis (Valenciennes, 1828) take a long time to grow to marketable size. In this study, 50 mg of crude recombinant Epinephelus lanceolatus growth hormone (rElGH) was added in each kg of pellet feed and applied as daily feed for humpback grouper culture. The objective of this study is to evaluate the effect of rElGH application in accelerate their growth and immunity.
The single dose of crude rElGH in commercial diet was applied daily for 120 days of nursery culture. The stocking density was 233 fish per m3 in fiber glass tank with continuous flowing water. Feed consumption and mortality was recorded daily and total body weight sampling was recorded for every 2 weeks. At the end of the treatment, the LD50 challenge test of pathogenic bacteria Vibrio fulnificus was conducted to measure the immunity level of fish studied.
Survival rate (SR), specific growth rate (SGR), feed efficiency (FE) and finally relative weight gain of the treatment group after feed rElGH was higher than control group (Table 1). Relative weight gain of the treatment group (%∆W:C) was 18.25% higher than control. SR of rElGH orally treatment after challenge test with LD50 of pathogenic bacteria V. fulnificus was 55% higher than control which was only 30% (Figure 2).
These results suggested that orally treatment of the rElGH able to stimulate growth and immunity. However, this treatment need to be continued until consumption size so the culture efficiency can be calculate in order to minimize cost and maximize profit.