Análise da porcentagem de fertilização em diferentes tempos de exposição ao choque térmico na indução à triploidia em jundiá (Rhamdia quelen)

Abstract

The objective of this study was to analyze the percentage of fertilization at different times of fecundation and exposure to heat shock induction of triploidy in silver catfish (Rhamdia quelen). The experiment was conducted during the month of december, using six males and six females. Fish passed through a 24 h fast, and were selected for carrying out the initial biometric which has been taken the measure of total weight (g). After weighing, the animals were subjected to a priming dose of HCG (Human Chorionic Gonadotropin), with the amount of 40 IU/kg and after 12 hours were submitted to a second dose of 360 IU/kg males received only one dose of 200u UI/kg at the second dose females. It was subsequently carried out the extrusion process for the collection of materials sex of male and female, which were homogenized and added to 10% water for fertilization. To obtain the triploid batch oocytes were placed in immersion in a water bath controlled and after 1 and 5 minutes of fecundation subjected to a thermal shock lasting 5, 10 and 15 minutes in a present temperature (36 °C) and subsequently conducted boxes polypropylene temperature compatible with the species (24 °C). After six hours, three random samples were collected from each treatment, 100 of each repetition, and analyzed on the magnifying glass. Fertilized eggs were separated from unfertilized eggs. Later, the two groups were accounted for and put back in polypropylene boxes. It was observed through statistical significant difference between treatment corresponding to 15 minutes of exposure (92.33% of eggs fertilized) compared to other treatments corresponding to five (73.33 %) and 10 minutes of exposure (63.33%) at 1 minute of fecundation. For the results obtained for different exposure times (5, 10 and 15 minutes) at 5 minutes of fecundation, through statistical analysis, no significant difference between treatments, concluding that fertilizing with 1 minute and 15 minute exposure yielded the highest fertilization rate of oocytes of silver catfish (Rhamdia quelen).