Effect of Olive Leaves and Propolis Extracts on Growth Performance, Immunological Parameters and Economic Efficiency using Nile Tilapia (Oreochromis niloticus)

Abstract

This study aimed to evaluate the effects of olive leaves ether extract (EEOL) and ethanol extract of propolis (EEP) on growth performance, body composition, nutrient digestibility, immunological parameters and economic efficiency in Nile tilapia, Oreochromis niloticus. Three Isonitrogenous (crude protein 35%), isocaloric (Digestable energy, 2900kcal) diets were fed to Nile tilapia averaging 19.7 ±0.94 g. A basal control diet had no additives, second and third diets containing 0.1% EEOL (1g/kg) and 0.4% EEP (4 g/kg) for successive 12 weeks. Results revealed that the dietary addition of EEOL and EEP had significant effects on growth performance parameters and protein utilization (P≤0.029). In addition, dietary supplement of EEP was more prominent than with EEOL and propolis extracts on fish final body gain and protein utilization. The carcass content from dry matter, protein and fat contents recorded higher values in EEOL or EEP supplemented groups. Furthermore, nutrient digestibility was improved by adding EEOL and EEP. The total leucocytes count, lymphocytes %, monocytes %, phagocytic activity, plasma total protein and globulin showed higher levels in fish groups with dietary addition of EEOL and EEP extracts than in fish fed the control diet. In terms of economic analysis, EEOL and EEP extract diet revealed the lowest cost per kg live weight of fish, along with the highest economic return and net profit. Addition of EEOL or EEP extracts to diet resulted in a more economically efficient production than in fish fed the control diet. Our results suggested that the dietary inclusion of EEOL (1g/kg) or EEP extracts (4g/kg) markedly enhanced growth performance, body composition, feed digestibility, immune status and economic efficiency using Nile tilapia.