In in vitro fermentation studies, feed samples can either be included in the in vitro rumen medium using filter bags or can be directly dispersed. The objective of this study was to investigate the effects of different pore sizes of filter bags on the rumen fermentation characteristics in an in vitro system. Corn, soybean meal, and timothy were ground to pass through a 1.0-mm screen and were formulated in the ratio of 70:7:23 based on DM, respectively. The formulated experimental diet (2g/DM) was put in F57 filter bags and R510 nylon bags (Ankom®) which pore sizes were 25 and 50 μm, respectively. An in vitro study was conducted to determine the rumen fermentation characteristics for 3, 6, 12, 24, and 48 h and rumen microbial community at 48 h of incubation. A significantly higher production of gas was observed in the R510 bags than in F57 at all the incubation times (p<0.01). IVDMD (p<0.01) and IVNDFD (p<0.01) were significantly higher, whereas pH (p<0.01) and NH3-N (p<0.01) were lower when R510 bags were used. In the VFA composition, acetate and butyrate were significantly higher (p<0.01) in R510 bags, and propionate and total VFA concentration did not differ (p=0.55 and 0.25, respectively) between F57 and R510 bags. The log copy numbers of bacteria and protozoa did not differ (p=0.69 and 0.94, respectively) between F57 and R510 bags, whereas those of fungi were significantly higher in R510 than in F57 bags (p<0.01). Therefore, the use of R510 may reflect actual rumen fermentation characteristics more precisely than those of F57 because increased gas production, nutrient digestibility and acetate, butyrate proportion were founded in R510.

ABSTRACT
Ⅰ. 서론
Ⅱ. 재료 및 방법
    1. 공시재료 및 공시동물
    2. 영양소 성분분석
    3. In vitro 발효 평가
    4. Genomic DNA 추출
    5. 재조합 plasmid의 제작
    6. Real-time PCR
    7. 통계 분석
Ⅲ. 결과
    1. In vitro 발효 평가
Ⅳ. 고찰
Ⅴ. 요약
Ⅵ. 참고문헌

• 문준범(부산대학교 생명자원과학대학 동물생명자원과학과) | Joon-Beom Moon (Department of Animal Science, Pusan National University)
• 김한빈(부산대학교 생명자원과학대학 동물생명자원과학과) | Han-Been Kim (Department of Animal Science, Pusan National University)
• 이정수(부산대학교 생명자원과학대학 동물생명자원과학과) | Jeong-Soo Lee (Department of Animal Science, Pusan National University)
• 박중국(농협사료) | Joong-Kook Park (Nonghyupfeed Co., Ltd)
• 신동은(농협사료) | Dong-Eun Shin (Nonghyupfeed Co., Ltd)
• 박병기(농협사료/강원대학교 동물생명과학대학) | Byung-Ki Park (Nonghyupfeed Co., Ltd/Department of Animal Science, Kangwon National University)
• 송재용(농협중앙회) | Jae-Yong Song (Institute of Livestock, Nonghyup Co. Ltd)
• 이세영(천안연암대학교 축산계열) | Se-Young Lee (Department of Animal Science, Yonam College)
• 서자겸(부산대학교 생명자원과학대학 동물생명자원과학과) | Ja-kyeom Seo (Department of Animal Science, Pusan National University) Corresponding Author