Effects of caprylic acid and β-cyclodextrin complexes on digestibility, energy balance, and methane production in Korean Hanwoo heifers

•Optimum dose level of caprylic acid (C8) and β-cyclodextrin (CD) complex in vitro was 0.67g/L which is 50 times lower than tested in previous in vitro experiments.•In vivo, C8-CD supplemented at 2% DMI did not modify total tract digestibility of nutrients and methane production.•It should be important to define the critical level of MCFA-CD complex in the diet beyond which MCFA influences methanogenesis in vivo.