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

The cyclodextrin (CD) complex with guest materials appears to be a promising solution to mitigate methane emissions without reducing energy intake. The purpose of this study was to determine the effects of caprylic acid (C8)-CD complex on methane production in vitro and in vivo. The C8-CD complex was added to diluted ruminal fluid (60 mL) at different levels (0, 0.17, 0.33, and 0.67 g/L) in triplicate and incubated anaerobically at 39 °C for 9 h. The pH (P < 0.001) and methane production (P < 0.05) decreased linearly but total VFA and total gas increased (P < 0.01) when the C8-CD complex supplementation was increased. Methane production decreased significantly (P < 0.05) by 28% at 0.67 g/L C8-CD complex when compared to the control. The effects of C8-CD complex supplementation at the level of 2% DMI on nutrient digestibility, energy balance, and methane production were further investigated using four Korean Hanwoo heifers (292 ± 3 kg) in a replicated 2 × 2 Latin square design. Each period consisted of 10 d of adaption and 4 d of measurement using four head hood respiratory chambers. Heifers were fed 4.8 kg of timothy hay and supplemented with 1.2 kg/d of ground corn grain and 130 g/d of corn gluten meal, on an as-fed basis, at 09:00 and 17:00 h. Nutrient digestibility and energy balance were not affected by the addition of the C8-CD complex. Supplementation of C8-CD complex decreased mean daily methane production up to 10%, but no significance compared to control. In conclusion, the effectiveness of C8-CD complex supplementation was observed in vitro but not in vivo. Therefore, further research is required to determine whether higher supplementation of C8-CD complex than 2.0% of DMI reduce methane production in vivo.