Growth performance of genetically improved farmed tilapia fry reared in a cage culture system on three experimental feeds

Abstract

The growth performance of Genetically Improved Farmed Tilapia (GIFT) fry reared under three artificial feeds were evaluated for final weight gain (FWG) and specific growth rate (SGR) over a period of 45 days in a cage culture system. Two laboratory-formulated diets having crude protein (CP) levels of 26% and 30% respectively and a commercially available feed for fry having 36% CP were used in this study. A total of 6660 fry having an average initial weight of 0.43 ± 0.02 g were stocked in nine cages (each with 2 m3 water capacity), with three replicates for each feed, at a stocking density of 370/ m³. At the end of the study period, the final weights of fingerlings (30% of the total from each cage) were recorded using an electronic balance and the FWG, SGR and cost effectiveness were calculated. The data were analysed using a one-way analysis of variance and post hoc tests. The average weight gains with 36%, 30%, 26% dietary CP was 2.83 ± 0.14 g, 2.46 ± 0.15 g and 2.23 ± 0.08 g respectively. Although the growth performance was comparatively better in fry fed with commercial feed, there was no significant difference (p ≥ 0.05) in FWG and SGR between the commercial feed and the 30% CP feed. Feed having 26% CP also had a reasonable SGR and FWG but these parameters were significantly lower than with the 36% CP feed. The mean survival rate of fingerlings for feed with 36%, 30% and 26% of CP were 83%, 82% and 84.5% respectively. The cost of commercial feed used in this study was approximately 1.5 times higher than the experimental feeds. Since the growth performance in GIFT fed with 30% CP feed was not significantly different from those fed with the commercial feed, the 30% CP formulation could be recommended over the commercial feed for comparable growth and economic gain.