Efeito do levamisol sobre o desempenho produtivo e como mitigador do estresse ao transporte em matrinxã (Brycon amazonicus)

Abstract

In the present work three experiments were carried out in order to evaluate the effects of dietary levamisole supplementation on growth performance and its efficacy to mitigate stress in matrinxã, Brycon amazonicus. In the first experiment (Chapter 2), the tolerance of matrinxã to Aeromonas hydrophila was verified, through the 96-h LD50 (lethal dose for 50% of the population in 96 hours), to be applied in the challenge test. The results suggest that matrinxã is tolerant to A. hydrophila infection, presenting a 96-h LD50 value of 6.66 x 1011 cells/mL of saline solution. A second study was done (Chapter 3) to evaluate the effects of levamisole ingestion on growth performance and on physiological responses of matrinxã under experimental conditions, and after the challenge with 60% of the 96-h LD50 of A. hydrophila. The results showed although levamisole has no effect on growth performance of matrinxã under experimental conditions, low dietary levels can stimulate part of the nonspecific immune system. However, the ingestion of levamisol does not mitigate the physiological alterations caused by the bacterial infection. In the third experiment (Chapter 4), the effects of supplementing 100 mg levamisole/kg diet, for different periods, on the stress responses of matrinxã after a 5-hour transport was evaluated. The results suggest that levamisole supplementation did not mitigate the negative effects caused by the transport stress. In addition, levamisole presented an immunosuppressive effect on leukocytes and trombocytes. However, the effects of stress observed in all the fish (from treatments with and without levamisole supplementation) demonstrated the adaptative capacity of this species, in which the most critical period was the first 24 hours after transport.