The objective of the present study was to investigate the effects of different red seaweeds on in vitro rumen fermentation characteristics and methane gas production. Five species of red seaweed (Chrysymenia wrughtii Yamada, CW; Hypnea sp., Hypnea sp.; Chondria crassicaulis, CC; Gelidium vagum Okamurae, GV; Hypnea saidana Holmes, HS) were obtained from National Institute of Fisheries Science (NIFS) in South Korea. The collected red seaweeds were washed for 3 minutes, and then samples were freeze-dried and ground to a size of a 1 millimeter. The buffered ruminal fluid (50 mL) was incubated with substrates and seaweeds (5% of substrates) at 39℃ for 48 hours. Total gas production was lower than red seaweed treatments excluding the CW treatment (p<0.05; 63.25 mL). Methane production was the lowest in CC treatment (p<0.05; 9.93 mL/g of digestible dry matter). The rumen pH of the red seaweed treatments ranged from 5.98 to 6.08, which was significantly the lowest in the GV treatment (p<0.05; 5.98). There was no significant difference in the total VFA concentration, but propionate (27.53%) was significantly highest in the CW treatment, whereas acetate (53.14%), iso-valerate (3.52%), valerate (1.72%), and A:P ratio (1.93) were significantly lowest (p<0.05). In conclusion, among the five species of red seaweeds, Chondria crassicaulis reduced in vitro methane production without negative effects on dry matter digestibility. Future studies will be needed to determine the optimal inclusion level of Chondria crassicaulis as feed additive to reduce enteric methane production.

ABSTRACT
Ⅰ. 서론
Ⅱ. 재료 및 방법
    1. 공시축 및 반추위액 채취
    2. 홍조류 채집 및 처리방법
    3. in vitro 배양
    4. in vitro 가스성상 및 반추위 발효성상 분석
    5. 통계분석
Ⅲ. 결과 및 고찰
    1. 총 가스 및 메탄 발생량 결과
    2. 반추위 발효성상 결과
Ⅳ. 요약
사사
Ⅴ. 참고문헌

• 김별(농촌진흥청 국립축산과학원 동물영양생리과 연구원) | Byul Kim (Researcher, Animal Nutrition and Physiology Division, National Institute of Animal Science, Rural Development Administration, Wanju 55368, Korea)
• 위지수(농촌진흥청 국립축산과학원 동물영양생리과 연구사) | Ji Soo Wi (Research Scientist, Animal Nutrition and Physiology Division, National Institute of Animal Science, Rural Development Administration, Wanju 55368, Korea)
• 이유경(농촌진흥청 국립축산과학원 동물영양생리과 연구사) | Yoo Kyung Lee (Research Scientist, Animal Nutrition and Physiology Division, National Institute of Animal Science, Rural Development Administration, Wanju 55368, Korea)
• 이성신(농촌진흥청 국립축산과학원 동물영양생리과 연구사) | Seong Shin Lee (Research Scientist, Animal Nutrition and Physiology Division, National Institute of Animal Science, Rural Development Administration, Wanju 55368, Korea) Corresponding author
• 김현상(농촌진흥청 국립축산과학원 동물영양생리과 전문연구원) | Hyun Sang Kim (Researcher, Animal Nutrition and Physiology Division, National Institute of Animal Science, Rural Development Administration, Wanju 55368, Korea)
• 이성대(농촌진흥청 국립축산과학원 동물영양생리과 연구관) | Sung Dae Lee (Senior Scientist, Animal Nutrition and Physiology Division, National Institute of Animal Science, Rural Development Administration, Wanju 55368, Korea)
• 황일기(해양수산부 국립수산과학원 수산식물품종관리센터 연구관) | Il Ki Hwang (Senior Scientist, Aquatic Plant Variety Center, National Institute of Fisheries Science, Mokpo 58746, Korea)