Application of Recombinant Growth Hormone for Growth Stimulation in Giant Gourami Juvenile (Osphronemus goramy) by Immersion

Abstract

This study aimed to determine the immersion frequency of recombinant common carp (CcGH) and giant gourami (OgGH) growth hormone in the growth stimulation of giant gourami juvenile. A total of 50 larvae at second day after first feeding, were immersed in 30 ppt salt water for 2 minutes, then transferred into 200 mL of 9 ppt saline water containing 30 mg/L CcGH in inclusion bodies form. Immersion was performed for 60 minutes with a frequency of 2, 3, 4 and 5 times at interval 7 days. The results showed that the highest (p<0.05) average body weight of giant gourami juvenile (2.232±0.190 g) was obtained at 4 times immersion treatment. The total dosage of 4 times immersion (120 mg/L OgGH) from the first experiment was then used in the second experiment to determine whether immersion frequency could be minimized. Fish larvae were immersed once a week, twice a week, and once a week for 2 weeks. The results showed that the highest (p<0.05) biomass (5482.58±110.70 g), and survival rate (87.38±8.84%) were obtained by once immersion time. Hence, both CcGH and OgGH could improve growth of giant gourami juvenile. The IGF-I mRNA expression level was increased significantly at 24 hours after OgGH immersion, and this suggested that IGF-I was involved in growth stimulation. Lower plasma cortisol levels in OgGH-treated fish after 180 minutes may also plays important role in growth induction. Thus, immersion of juvenile once a week in 120 mg/L OgGH solution can be applied to enhance the growth of giant gourami with a high survival rate.