Comparative Analysis of Gut Microbiota and Methanogenic Archaea in Korean Cattle Based on Age and Feed with Ulva sp. Additive

The growing interest in regulating methane production in ruminants has highlighted the importance of elucidating the blueprint of gastrointestinal microbiota. Despite advancements in analytical techniques, data on the microbial communities in ruminants' gastrointestinal systems remain limited. This study aimed to investigate the microbial communities in the gastrointestinal tract of Korean native cattle (Hanwoo) by analyzing rumen fluid, feces, and the impact of dietary Ulva sp. supplementation. Results revealed that Firmicutes dominated across all rumen fluid and fecal samples. However, differences in dominant microbial taxa were observed between rumen fluid and fecal samples, as well as between calves and growing cattle. In calves, Spirochetes and Methanocorpusculum were predominant, indicating age-dependent differences in the microbial community structure. The prevalence of Paeniclostridium ghonii in feces provided indirect insights into the digestive capacity influenced by carbohydrate content. Notably, Methanosphaera_uc was detected at very low levels in Ulva sp.-supplemented cattle, suggesting that dietary conditions can alter the composition of methanogenic archaeal communities. These findings offer foundational data for the exploration of microbial communities in response to environmental and life cycle variables in cattle. Furthermore, this study could be useful data for the development of green seaweed(Ulva sp.)-based additives, to regulate methanogenic archaea in ruminants.