Comparison of methods for hatchery-scale triploidization of European catfish (Silurus glanis L.) |
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| Authors: | O Linhart P Haffray C Ozouf-Costaz M Flaj&#;hans & M Vandeputte |
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| Institution: | University of South Bohemia, Department of Fish Genetics and Breeding, Research Institute of Fish Culture and Hydrobiology, Vodňany, Czech Republic,;French Union of Poultry and Fish Breeders, Rennes Cedex, France,;Laboratoire d'Ichthyologie, National Museum of Natural History, Paris Cedex, France,;Laboratory of Fish Genetics, INRA, Jouy-en-Josas, France |
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| Abstract: | Heat-, cold- and hydrostatic pressure shocks were applied in order to improve triploidy induction in European catfish ( Silurus glanis L . ). A 41°C heat shock (45 s, starting 9 min after gamete activation) provided 88% triploids and a high percentage of malformation (38.8 ± 4.1%). The superior 6°C cold shock (20 min, starting 9 min after gamete activation) gave 100% triploids and a 33.4 ± 3.8% triploid yield. The earliest hydrostatic treatments (600 kg cm2), lasting 4 min and starting 3 min after gamete activation, gave 97.8 ± 1.8% triploids and a 33.7 ± 16.9% triploid yield. The ploidy level was investigated using four approaches: karyotyping, quantification of Ag-stained nucleoli per cell, flow cytometry, and erythrocyte nuclear sizing by computer-assisted image analysis. Induction of triploidy under mass conditions in three experiments gave triploid percentages of 74%, 83% and 66%. Five months later, the percentage of triploids significantly decreased to 12.4%, 8.2% and 21.4%. The growth performance of yearlings was better in diploids than in triploids. Differences between diploids and triploids were 13.5% (NS), 27.6% (P < 0.001) and 25.4% (P < 0.05) in the three experiments. Analysis of variance showed the influence of ploidy (P < 0.001) on growth rate, and multiple range analysis (LSD) assessed differences between total diploids (12.6 g) and total triploids (9.5 g) at the P < 0.01 level. |
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