In the present study MEO, YC and malate supplementation did not affect DMI, final body weight, ADG and FCR in growing lambs. Dietary YC supplementation increased CP and NDF digestibility. Dietary YC and malate supplementation increased ruminal propionate proportion without affecting total VFA and increased plasma glucose concentration. Further study is required to investigate the combined effect of essential oil, YC and malate on ruminal lactic acid producing and fermenting bacteria and on microbial protein synthesis in lambs fed high-concentrate diets.