Effects of Codium fragile Extract Additive on In Vitro and In Vivo Methane Production and Fermentation Characteristics of Korean Native Steers (Hanwoo)

The present study was conducted to demonstrate the effects of Codium fragile extract on methane production using in vitro and in vivo experiments. An in vitro batch experiment was conducted to evaluate different inclusion levels of Codium fragile extract (0, 0.25, and 0.5% of substrate dry matter). Methane production significantly decreased in the 0.5% treatment (p < 0.05), whereas dry matter digestibility and total volatile fatty acid concentration were not significantly affected (p > 0.05). Based on the in vitro results, an in vivo feeding experiment was conducted using a 0.5% inclusion level of Codium fragile extract on Hanwoo steers. Methane emissions were significantly decreased by approximately 10% in steers fed Codium fragile extract (p < 0.05). In contrast, rumen fermentation characteristics, feed intake, average daily gain, and blood parameters were not significantly different between the treatments (p > 0.05). These results demonstrate that a dietary additive with 0.5% Codium fragile extract effectively reduced methane emissions without negatively affecting rumen fermentation and growth performance in Hanwoo steers.