Effects of Eucalyptus globulus leaf extract on growth performance, feed utilization and blood biochemistry of Nile tilapia, Oreochromis niloticus

Abstract

The effects of Eucalyptus globulus Labill. extract in diets of Nile tilapia (Oreochromis niloticus Linnaeus, 1758) were studied. Five diets (500 g each) supplemented with 0 ml (T 0), 5ml (T 5), 10 ml (T 10), 15 ml (T 15) and 20 ml (T 20) of E. globulus extract were fed to O. niloticus for 12 weeks. Group fed diet T 10 recorded the highest final weight (42.27 g), weight gain (36.97 g) and specific growth rate (3.72). The highest protein efficiency ratio (2.36), feed efficiency (0.70) and condition factor (1.31) were observed in group fed diet T 10. Compared to fish fed diet T 0, all groups fed E. globulus extract recorded significantly higher levels of crude protein content in the whole body. Hemoglobin concentration increased with increasing levels of E. globulus extract up to T 10 but decreased after further increase in E. globulus extract in diets. Increasing E. globulus extract levels in diets resulted in a significant decrease in aspartate aminotransferase. Group fed diet T 5 recorded the least (17.50) alkaline phosphate and was significantly lower than all other groups. Globulin concentration decreased with increasing E. globulus extract in diets. This study concludes that dietary administration of E. globulus promotes growth performance, feed utilization and increases the main hematological and biochemical parameters of O. niloticus fish. For optimum growth, 10 ml per 500 g (T 10) feed is recommended. This study provides new information on applications of eucalyptus and, at the same time, promotes rational development and utilization of eucalyptus resources.