The effects of Eucalyptus globulus extract in diets of Nile tilapia (Oreochromis niloticus) were studied. The fishes were divided into 5 groups before being fed diets supplemented with 0 percent (T 0), 5 percent (T 5), 10 percent (T 10), 15 percent (T 15) and 20 percent (T 20) of E. globulus extract for 12 weeks. All the groups fed E. globulus extract recorded significantly higher levels of protein content in the whole body. Lipid content was significantly influenced by E. globulus extract levels. The highest lipid content was recorded in group fed diet T 10 and was significantly higher than all other groups (p<0.05). The best protein efficiency ratio and feed conversion ratio were observed in groups fed diets supplemented with E. globulus at 5 percent and 10 percent. Hemoglobin concentration increased with increasing levels of E. globulus extract up to T 10. Increasing E. globulus extract in diets of O. niloticus resulted in increasing levels of Alanine aminotransferase and aspartate aminotransferase. Also, the study showed both an increase in total protein and albumin concentration as E. globulus extract increased in diets. There was however a significant decline in globulin content when E. globulus extract was increased from T 5 to T 20. The total protein serum was significantly higher in fish fed on diet containing E. globulus extracts when compared to basal diet. Therefore, dietary administration of E. globulus can promotes growth performance and increases the main hematological and biochemical parameters of Nile tilapia (O. niloticus) fish. This study provides new applications of eucalyptus and at the same time, promotes rational development and utilization of eucalyptus resources.
Key words: Eucalyptus globulus, hematology parameters, growth performance, blood biochemistry, Nile tilapia