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Abstract
The experiment was conducted to evaluate the effects of hormone doses on reproductive performance of giant trevally cultured in Khanh Hoa province. Broodstocks were injected with three hormone doses including: (1) LHRHa 25 µg + HCG 800 IU/kg female; (2) LHRHa 35 µg + HCG 1100 IU/kg female and (3) LHRHa 45 µg + HCG 1400 IU/kg female. Then, the optimum hormone dose was applied to induce spawning of giant trevally under practical conditions. The results showed that there were significant effects of hormone doses on fertilization rate and hatching rate, in which the females injected with LHRHa 35 µg + HCG 1100 IU/kg had significantly higher fertilisation rate and hatching rate than those injected with the highest hormone dose (P < 0,05). There were no effects of hormone doses on the deformity, larval length, yolk-sac size, oil droplet size and survival of 3 day after hatching (3DAH) larvae. Under practical conditions, the results indicated that females that received with single injection showed relatively lower egg fecundity and fertilisation rate, 69.93 g/kg and 51.80% in comparison to those injected with two injection times, 81.97 g/kg and 74.12% respectively. Generally, the hormone dose of LHRHa 35 µg + HCG 1100 IU/kg with two injected times should be recommended for breeding of giant trevally.
Key words: hormone, giant trevally, reproduction, larvae, survival