CgGH and IGF-1 expression level and growth response of G4 transgenic mutiara strain catfish (Clarias gariepinus) reared at different stocking densities.

This study aimed to evaluate the growth response of G4 transgenic mutiara catfish reared at different stocking densities. The relative expression ratio levels of CgGH/ß-actin and IGF-1/ß-actin mRNA was measured using quantitative real-time PCR (qRT-P CR) in G4 mutiara catfish. Fish were kept for 8 weeks at different stocking densities (treatment A, 15 fish/100 L; B, 12 fish/100 L; C, 10 fish/100 L for transgenic fish; and A*, 15 fish/100 L for non-transgenic fish). The average increase in body weight of G4 mutiara catfish was 1.9–2.3 times higher compared to non-transgenic mutiara catfish at the same stocking densities. The growth response indicates an overexpression of the growth hormone (GH) in G4 mutiara catfish, displaying expression levels 1.3–2.9 higher than in non-transgenic fish. The use of high stocking density (treatment A, 15 fish/100 L) induced overexpression of the exogenous GH (CgGH) and increased the body protein content, as well as improved the feed conversion ratio, protein retention value, and fish protein efficiency ratio, leading to faster body weight gain of G4 transgenic versus non-transgenic mutiara catfish. The growth of G4 catfish in treatments B and C remained higher than in treatment A* (non-transgenic fish), but the growth of non-transgenic catfish was slower. The induction of the CgGH expression level caused an increase in the growth, protein retention, protein efficiency ratio, and IGF-1 expression level of G4 transgenic mutiara catfish. The permanent inheritance of CgGH in G4 fish has the potential to increase the mass production of commercial catfish culture. [ABSTRACT FROM AUTHOR]