Dietary supplementation with essential oils of Lippia sidoides, Ocimum gratissimum and Zingiber officinale on the growth and hemato-immunological parameters of Colossoma macropomum challenged with Aeromonas hydrophila

This study aimed to evaluate the effects of essential oil (EO) of Lippia sidoides, Ocimum gratissimum, and Zingiber officinale in the diet of tambaqui (Colossoma macropomum) growth, hematological and immunological parameters. The survival rate was also calculated after challenge with Aeromonas hydrophila. Seven diets containing 32 % crude protein were formulated as follows: control (0 g/kg of EO), 0.625 and 1.25 g/kg of L. sidoides EO; 1.25 and 5.0 g/kg of O. gratissimum EO; 1.25 and 5.0 g/kg of Z. officinale EO, in triplicate. Tambaqui fed diets supplemented with EO of L. sidoides, O. gratissimum, and Z. officinale did not present significant differences in the growth parameters. After 30 and 60 days of feeding, performance and hematological parameters were evaluated. Reductions in total thrombocytes number occurred after 30 days of feeding with 1.25 g/kg and 5.0 g/kg O. gratissimum EO. After 60 days of feeding, fish were challenged with A. hydrophila (1.6 x 108 UFC mL(-1)) and were observed for 10 days. Fish fed with diets supplemented with L. sidoides EO at 0.625 g/kg and 1.25 g/kg showed a higher nonspecific immune response through the increased respiratory activity of leukocytes after challenge. Additionally, there was a decrease in plasma glucose levels and no alteration of the total protein levels. Moreover, after the challenge, the highest survival rate occurred among fish fed 0.625 g/kg L. sidoides EO, while treatments with O. gratissimum and Z. officinale EO did not affect fish survival. This is the first report of L. sidoides EO in tambaqui diets. More studies are warranted to adjust the concentration and periods of treatment regarding diets supplemented with L. sidoides EO or thymol in treatment of bacterial fish diseases.