Stress evaluation in dourado females (Salminus brasiliensis) submitted to two different methods of induced spawning

Abstract

The goals of this study were to evaluate dourado female egg viability submitted to stress condition caused by two different reproductive induction methods, extruded and semi-natural. Sixteen females randomly chosen were induced with pituitary extract and allocated in two groups; the first, in which oocytes were manually extruded and the second group, females were allowed to naturally spaw. Blood samples were collected for glucose, cortisol and hematocrit determinations as well as for red blood cells and white blood cells smears evaluations. A control group had its blood collected before hormonal induction. Fertilization rate was 40.6 and 91.7% for extruded and semi-natural methods, respectively, and the survival rate was higher in semi-natural groups. Both experimental groups showed higher glucose and cortisol levels compared to control group. The results for hematocrit, hemoglobin concentration and erythrocytes numbers did not differ among groups. Extruded and semi-natural procedures elevated monocytes percentage. In conclusion, the semi-natural procedures are more efficient than extruded method and should be taken into account for Salminus brasiliensis handling of breeders. Key words: Fish breeders, reproductive methodology, hematological parameters.