O lambari, Astyanax bimaculatus, é uma das espécies nativas com potencial zootécnico para a aquicultura, e se destaca com características desejáveis para o cultivo, logo, estudos referentes à quantidade ideal de alimento são necessários para melhorar o desempenho zootécnico da espécie. Sendo assim, objetivou-se avaliar e descrever a influência da frequência alimentar sobre o crescimento do A. bimaculatus. Matrizes de A.bimaculatus foram capturadas em uma piscicultura maranhense, hipofisadas em laboratório com hormonôno sintético e em seguida casais foram estocados em sistema de desova semi-induzida. Após a eclosão as pós-larvas foram transferidas para um tanque berçário, para o treinamento alimentar com ração comercial durante 20 dias. Posteriormente os alevinos foram submetidos à biometria e transferidos para unidades experimentais com tratamentos pré-estabelecidos, com três diferentes frequências alimentares, sendo duas, três e quatros vezes ao dia, até a saciedade aparente, o monitoramento da água foi realizado semanalmente. Os resultados demonstraram que a alimentação natural juntamente com a ração comercial 45%PB influenciaram signficamente. Os parâmetros físico-químicos da água mantiveram-se dentro dos padrões aceitáveis para a espécie durante toda a pesquisa, e os índices zootécnicos apresentaram crescimento linear. Concluiu-se que o crescimento do A. bimaculatus é influenciado pela frequência alimentar. Considerando o ganho de peso, indica-se que os alevinos de A. bimaculatus podem atingir o melhor desempenho zootécnico quando alimentados quatro vezes ao dia. Ressaltando o favorecimento na conversão alimentar proveniente do aumento na frequência alimentar.
Conservation of fish gametes is critical to increasing the success of induced reproduction and is widely used in aquaculture farming . Refrigeration at temperatures close to 4°C is one of the techniques commonly adopted to preserve semen for short periods, to keep semen quality feasible for hours, days and even weeks, maintaining its fertilization capacity (Contreras et al., 2019;Shaliutina et al., 2013). For this to occur, it is necessary to use diluting solutions that provide a protective medium, while both nourishing and reducing cell metabolism of sperm during storage conditions (Silva et al., 2018).Studies with fish have demonstrated the positive effects of refrigeration associated with the use of cryoprotectants among which
The aim of the current study is to evaluate gene expression patterns of LH (lhr) and estrogen (er) receptors and plasma steroid levels during testicular development in Genyatremus luteus. Males were histologically classified as immature (n=7), maturing (n=7) and mature (n=7), based on the cellular structure of their testes. Plasma 11-KT concentration recorded peak at the final maturation stage. The highest plasma 17α-OHP concentrations were observed at the immature stage; they decreased at the maturation and mature stages. On the other hand, 17β-estradiol (E2) recorded higher concentrations at the maturation stage. Er expression has significantly increased along the maturational development of animals’ testes. The mRNA observed for the LH receptor has decreased from immature to maturing stage; it presented expression peak at the mature stage. There was high association between receptor gene expression and plasma steroid levels, mainly E2. The current study was the first to feature different reproductive maturation stages in male G. luteus specimens, based on cellular, endocrine and molecular aspects. In addition, it has shown that the gene expression profile for er and lhr receptors, as well as plasma 11-KT and E2 concentrations, are directly linked to testicular maturation, although they are not necessarily associated with the gonadosomatic index.
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