Suchergebnisse

The great commercial potential of Nile tilapia is due to features such as its high production performance, its adaptability to different farming systems, and the development of genetic varieties with superior performance. Therefore, the objective of this study was to evaluate the performance of two varieties, GIFT (Genetic Improvement of Farmed Tilapia) and Supreme, grown in hapas in concrete tanks and grown in excavated ponds. Were used 200 and 1234 fingerlings of both varieties, GIFT and Supreme (average initial weight of 0.83 g), for farming in hapas and ponds, respectively. Biometric measurements were taken at four farming stages (fingerling, juvenile, growth, and fattening). Were measured weight (g), total length (cm), standard length (cm), trunk length (cm), head length (cm), head height (cm), body height (cm), weight gain (g) and head/edible-part ratio. For all parameters and in all stages, superior results were observed for tilapia reared in excavated ponds. When the varieties were compared, GIFT had the best performance for most parameters in the fingerling stage, and for weight, total length, and body height in the juvenile stage. Both varieties grew better in excavated ponds. Moreover, GIFT showed higher growth than Supreme during all stages when grown in excavated ponds. Supreme showed higher growth than GIFT in hapas only in the growth stage. Thus, it is concluded that the rearing in excavated ponds provided better results, with superiority of the GIFT variety, which was more able to take advantage of the favorable conditions of this system.

<p>As espécies nativas de peixes no Brasil tem alto potencial para utilização dentro da piscicultura, porém, seus estoques naturais vêm sofrendo redução nos últimos anos. Para diminuir esse impacto negativo, estudos voltados à conservação estão sendo realizados e cada vez mais, a obtenção de ferramentas genéticas que permitam a discriminação de parâmetros populacionais toma maior importância. Objetivou-se através do presente estudo avaliar um conjunto de <em>primers </em>microssatélites heterólogos em jundiá (<em>Rhamdia quelen</em>) e piapara (<em>Leporinus elongatus</em>). Foram analisadas amostras de nadadeira caudal de 15 reprodutores de cada espécie. A extração de DNA foi realizada utilizando o protocolo com NaCl. A integridade do DNA extraído foi checada em gel de agarose 1%. Foram avaliados 20 <em>primers </em>desenvolvidos para as espécies: <em>Piaractus mesopotamicus</em>, <em>Colossoma macropomum</em>, <em>Prochilodus lineatus</em>, <em>Brycon opalinus </em>e <em>Oreochromis niloticus. </em>Foi observada amplificação cruzada de quatro <em>primers </em>das espécies <em>B. opalinus </em>e <em>P. lineatus </em>(BoM12, Pli43 e Pli60 em <em>R. quelen </em>e BoM2, Pli43 e Pli60 em <em>L. elongatus</em>). Os <em>primers </em>de <em>P. mesopotamicus</em>, C<em>. macropomum </em>e <em>O. niloticus </em>não mostraram amplificação cruzada nas duas espécies analisadas. Os resultados indicaram a possibilidade de uso dos três <em>primers </em>heterólogos amplificados em estudos genéticos em <em>R. quelen </em>e <em>L. elongatus</em>.</p>

The genetic diversity of Piaractus mesopotamicus (pacu) and Leporinus elongatus (piapara) broodstocks used in restocking programs in the rivers Paraná and Paranapanema is analyzed. One hundred and twenty specimens (two broodstocks of each species) from fish ponds in Palotina PR Brazil and in Salto Grande SP Brazil were assessed. Ten primers produced 96 fragments, comprising 68 (70.83%) and 94 (97.92%) polymorphic fragments for P. mesopotamicus and L. elongatus broodstocks, respectively. Differences (p &lt; 0.05) in the frequency of 15 and 27 fragments were detected for each species, without exclusive fragments. Shannon Index (0.347 - 0.572) and the percentage of polymorphic fragments (57.3% - 94.8%) revealed high intra-population genetic variability for all broodstocks. Results of molecular variance analyses (AMOVA) showed that most variations do not lie between the broodstocks but within each broodstock (89%). Genetic (0.088 and 0.142) and identity (0.916 and 0.868) distance rates demonstrated similarity between the broodstocks of each species, corroborated by Fst (0.1023 and 010.27) and Nm (4.18 and 4.33) rates, with a slight genetic difference due to genic flux. High intrapopulation genetic variability and similarity between the broodstocks of each species was also detected, proving a common ancestry.