Abstract
The aim of the present study was to investigate the growth performance of Nile tilapia immersed in 17α-methyltestosterone (MT) and recombinant giant grouper growth hormone (rElGH), and fed a rElGH-enriched diet. A total of 200 tilapia larvae aged 10 days and 14 days post hatching was immersed in 1 liter of 30 g/L saline water for 3 minutes, then in freshwater containing either MT, MT+rElGH, or rElGH for 4 hours. The MT dose was 2.0 mg/L and rElGH was 2.5 mg/L. As control was treatment without MT and rElGH. Fish were maintained in 250-L aquariums for 6 weeks and then moved to net cages for 8 weeks of rearing. The rElGH-enriched diet was fed to the 6-week-old fish for a month, and then fed a non-enriched diet. Each treatment was triplicates. The result showed that the daily growth rate (DGR), biomass gain (BM), survival (SR) and feed (artemia nauplii) consumption during maintenance in the aquariums in the rElGH and MT+rElGH treatments were higher (P<0.05) than in the control. The higher DGR and BM at net cage rearing and lower feed conversion ratio (P<0.05) were also found in MT and MT+rElGH treatments. None of the treatments showed any difference in survival (P>0.05). Profits estimation in the MT and MT+rElGH treatments were 63.38% and 57.91% higher than the control. The present study concluded that higher Nile tilapia farming performance could be obtanied by MT immersion in the larval phase and feeding juvenile on the rElGH-enriched diet.
Highlights
The growth of male Nile tilapia is faster than that of females (Sudrajat et al, 2007; Chakraborty 2011), making the cultivation productivity of monosex male Nile tilapia is higher and more profitable
Results showed that the daily growth rate (DGR) of fish treated with rElGH and those treated with MT+rElGH were the same and both were higher (P
The results of this study were in line with the results reported in Wassermann and Afonso, (2003) that the use of MT through the immersion of Nile tilapia larvae has been proven to increase the percentage of males by 91.6%; even though there were no differences in DGR in the first month post treatment (Chakraborty et al, 2011)
Summary
The growth of male Nile tilapia is faster than that of females (Sudrajat et al, 2007; Chakraborty 2011), making the cultivation productivity of monosex male Nile tilapia is higher and more profitable. Administration of rGH through immersion has been proven to increase gourami larvae biomass by 79.8% compared to the control (Irmawati et al, 2012). In Nile tilapia larvae, using the same method at a dose of 2.5 mg L-1, it could increase growth by 49.6% compared to the control (Setyawan et al, 2014). In the previous study, the productivity and potential profit of aquaculture using feeds with different protein concentrations and enrichment with rElGH in Nile tilapia rearing in ponds was tested (unpublished data). The best performance was found in treatment using feed with a protein content of 28% and enriched with giant grouper recombinant growth hormone (rElGH)
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