Addition of Lippia sidoides Essential Oil to Tilapia Diet: Performance Analysis, Blood Parameters, and Challenges of Air Exposure and Experimental Infection

This study evaluated the effects of Lippia sidoides essential oil (LSEO) as a growth and health promoter for juvenile tilapia subjected to stress induced by air exposure and experimental infection with Aeromonas hydrophila. Juvenile were allocated to 15 tanks (in triplicate) and fed diets containing 0.0% (Control), 0.05%, 0.1%, 0.2%, or 0.4% LSEO for 33 days. For the air exposure challenge, five fish from each tank were exposed to air for five minutes after the feeding period. Blood samples were collected for hematological analysis. For the infection challenge, six fish from each tank were intraperitoneally inoculated with 100 µL of A. hydrophila and monitored for ten days. Hematological and histomorphometric parameters were assessed. The results indicated that the 0.4% LSEO supplementation reduced feed conversion ratios (P < 0.05). Before the challenges, LSEO concentrations influenced total counts of neutrophils, basophils, and monocytes (P < 0.05). After the air exposure and infection challenges, no significant differences were observed among treatments for these parameters (P > 0.05). Regarding hematimetric indices, all parameters were affected by LSEO concentrations prior to the challenges (P < 0.05). Although LSEO supplementation improved feed conversion, it did not mitigate the hematological alterations caused by the stress challenges.

Key words
Aquaculture; Haematology; Immunity; Oreochromis niloticus; Phytotherapy