The efficacy of using olive cake as a by-product in broiler feeding with or without yeast

The effects of inclusion of olive cake (OC) at 0, 5 and 10% in broiler diets were investigated during 1-28 d of age. Each level of OC was fed with or without yeast (Saccharomyces cerevisiae) at 0.2 and 0.4 g/kg. Thus, the experimental design had a factorial arrangement that included three concentrations of OC by three concentrations of yeast (unsupplemented control, 0.2 and 0.4 g/kg yeast supplementations). Each diet was fed to eight replicates of five male chickens each. Growth performance, European production efficiency index (EPEI), blood lipid constituents, inner body and lymphoid organs were studied. The results indicate that OC can be fed at 5% with yeast supplementation at 0.4 g/kg to broiler chickens during 1-28 d of age, resulting in the best body weight gain (BWG), feed conversion ratio (FCR), and EPEI. Yeast supplementation at 0.2 g/kg to diets containing 0% and 5% OC and at 0.4 g/kg to diets containing 10% OC resulted in the highest survivability rate (100%). In addition, OC in broiler diets up to 10% did not adversely affect carcass traits and inner organs. In conclusion, OC can be safely fed to broiler chickens during 1-28 d of age up to 10%, while reducing the environmental pollution caused by the accumulation of OC after the expansion in the cultivation of olives for oil extraction for human consumption. However, the best productive performance and production index were obtained when 5% OC was supplemented with 0.4 g/kg yeast.