The effects of different protein levels in the diet on reproductive indexes of Rhamdia quelen females

The nutrition of broodstock is one of the least studied areas because biological mechanisms, such as gonadal maturation, are extremely complex processes and are affected by several nutrients, especially in continuous spawning fish with short vitellogenic periods as Rhamdia quelen. For the present experiment, 66, 14-month-old female R. quelen were randomly distributed in six cages and fed for 90 days with three isocaloric diets containing either 28%, 34%, or 40% crude protein. Data were collected at the beginning of the experiment (day zero) and after 45 and 90 days, for evaluation of several parameters as final weight, length, condition factor, hepatosomatic, gonadosomatic and visceral fat indexes, amino acids in the ovaries, plasma enzymes aspartate aminotransferase (AST) and alanine aminotransferase (ALT), total plasma protein, testosterone, 17β-estradiol, free amino acids (AAL), and triglycerides (TG). From these females, the reproductive cycle, egg characteristics and larval size were evaluated. The results showed that the different protein levels in diets had no effect on the main physiological and reproductive parameters. In conclusion, the 28% crude protein dietary level was sufficient for maintenance of the broodstock and the reproductive indexes of R. quelen females.