Survival and hematological profile of Nile tilapia Oreochromis niloticus fed diet with oregano Oreganum vulgare L. leaf extract at different concentrations challenged with Pseudomonas aeruginosa

Thisrnstudy assessed the survival and hematological profile of Nile Tilapia Oreochromisrnniloticus fed with different concentrations of oregano leaf extract (OLE)rnafter 24 hours of bacterial stress challenge. The fish were fed with oreganornleaf extract at 1 ml, 2 ml, 3 ml, and 0 ml, served as the control. Fish bloodrnsamples were collected 6 weeks after rearing and 24 hours after the bacterialrnstress challenge. The fish were injected with 0.2 ml of Pseudomonas aeruginosarnintraperitoneally. As a result, Pseudomonas aeruginosa had arnsignificant effect on the blood parameters of the fish after the experimentalrnchallenge. RBC counts of Nile tilapia fed with a commercial diet decreasedrnwhile the fish fed with OLE were maintained. This result showed that OLErnprotected the fish from infection during the bacterial stress challenge. Thus,rnit can be concluded that at 3ml/kg, oregano leaf extract acts as anrnimmunostimulant for Oreochromis niloticus against Pseudomonasrnaeruginosa. Further studies on the different fish species challenge arernrecommended.