RESUMO
The production of captive fish is only possible through artificial reproduction, but manipulation is a known stressor stimulus. Thus, the objective of the present study was to evaluate the effects of different eugenol concentrations (0, 30, 40, 50 and 60â¯mg/L) during reproductive management of Rhamdia quelen. Seventy-five mature male R. quelen were randomly distributed among the five treatments, and blood samples were collected at the time of semen collection to measure plasma cortisol. The following parameters were evaluated in the fresh semen samples: motility, motility duration, concentration and fertilization rate. The following parameters were evaluated in the frozen semen samples: motility, motility duration, morphology, membrane integrity, DNA integrity and mitochondrial functionality. The animals anesthetized with eugenol at concentrations of 40 and 50â¯mg/L had lower levels of plasma cortisol (88.4 and 83.3â¯ng/mL, respectively) than the control (147.1â¯ng/mL). For fresh semen, the control treatment presented the highest rate and time of motility but differed (Pâ¯<â¯0.05) only from the animals treated with 60â¯mg/L eugenol. For the cryopreserved semen the highest rates and motility time were observed in the control treatment and in the animals anesthetized with 40â¯mg/L eugenol, differing (Pâ¯<â¯0.05) from anesthetized animals with 50 and 60â¯mg/L. Mitochondrial functionality was higher in fish anesthetized with 30â¯mg/L eugenol differing only for animals anesthetized with 60â¯mg/L. There was no difference between treatments for sperm concentration and fertilization rate of fresh semen. There were no differences (Pâ¯>â¯0.05) between treatments in the parameters of membrane integrity, DNA integrity and% of normal spermatozoa after thawing of the cryopreserved semen samples. The use of 30, 40 and 50â¯mg/L eugenol maintained the seminal quality of the fresh semen, and the quality of the thawed semen was maintained with 30 and 40â¯mg/L eugenol. These results show that stress reduction can be reconciled with reproductive management without compromising reproductive performance.