Preliminary observations on growth and survival of Oreochromis spilurus x GIFT Oreochromis niloticus F1 reciprocal hybrids in fresh and seawater |
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| Authors: | Mohammad T Ridha |
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| Institution: | Mariculture and Fisheries Department, Food Resources and Marine Sciences Division, Kuwait Institute for Scientific Research, , Salmiyah, Kuwait |
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| Abstract: | Tilapia has a significant potential for culture in saline environments. There is an increasing demand among tilapia producers to develop a tilapia hybrid that can survive well in marine water conditions. This study compared mean weight (MWT), daily growth rate (DGR), specific growth rate (SGR), survival, feed conversion ratio (FCR), condition factor (K), production rate (PR) and rate of skin lesions, and tail and fin rot as well as eye cataract in the Genetically Improved Farmed Tilapia strain (GIFT) of the Nile tilapia, Oreochromis niloticus (NN) and the salt‐tolerant Oreochromis spilurus (SS), and their F1 reciprocal hybrids; O. niloticus ♀ x O. spilurus ♂ (NS) and O. spilurus ♀ x GIFT O. niloticus ♂ (SN) in freshwater (0 g L?1) and seawater (40 g L?1). Fish (3.5 g) were stocked at 150‐fish m?3 and fed with sea bream pellets (47% protein) for 180 days. Results showed that in seawater, the SN hybrid had the highest values for MWT (165.9 g), DGR (0.9 g fish?1 day?1), SGR (2.14% day?1), survival (96.3%), PR (23.9 kg m?3) and best FCR (1.53) followed by the NS hybrid and the NN parent. Both hybrids had significantly lower rates of skin lesions and fin and tail rot than the NN genotype. In freshwater, the NN had the highest values for MWT (255.1 g), DGR (1.40 g fish?1 day?1), SGR (2.38% day?1), K (2.13%) and PR (34.9 kg m?3) followed by the NS and SN hybrids. High estimate of heterosis for MWT (41.3%), DGR (42.5%), SGR (10.7%) and survival (22.1%) was obtained in the hybrids reared in seawater, indicating that a hybrid vigor was produced and the fast growth trait from the GIFT parent was successfully combined with the salinity tolerance trait from the O. spilurus parent. The better growth performance and survival of the SN hybrid in seawater indicate that this hybrid is more suitable for culture in seawater than its reciprocal hybrid. |
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| Keywords: | F1 hybrids GIFT strain Growth Heterosis hybrid vigor Nile tilapia O spilurus Seawater Skin lesions |
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