The objective of this study was to determine the effect of different pregnancy stages on the eating and ruminating behavior of Hanwoo heifers (Bos taurus coreanae). A total of twelve Hanwoo heifers were divided into four groups depending on pregnancy stage: C: before pregnancy, 9 months old, T1: 3 months pregnant, 16 months old, T2: 6 months pregnant, 19 months old, T3: 9 months pregnant, 22 months old (3 replicates per group). Concentrate of 1% of the body weight was fed to them. Roughage was provided at ad libitum to all treatments. Our results revealed that the intake of roughage was the highest in the T3 group (at 3.68 kg) and the lowest in the C group (at 1.02 kg, p<0.05). Total intake in the order from high to low was: T3 > T2 > T1 > C (p<0.05). The rate of dry matter intake compared to body weight (DMI/BW, %) from high to low order was: T3 > T2 > T1 > C (p<0.05). Eating time, ruminating time, and chewing time were the highest in T3 group (p<0.05). Resting time was the highest in C group (p<0.05). The number of bolus and the number of total chews were significantly higher in T3 compared to those in other groups. However, ruminating time per bolus was not significantly difference among groups. The number of chews per bolus from high to low order was: C > T1 > T3 > T2 (p<0.05). The number of bolus per minute was not significantly different among groups. The number of drinking and the number of defecating were significantly higher in C and T1, respectively (p<0.05). However, the number of urinating had no effect according to pregnancy stage. Eating rate and chewing efficiency were significantly higher (p<0.05) in accordance with pregnancy stage (T3 > T2 > T1 > C). Ruminating efficiency was significantly (p<0.05) higher T1 than that in other groups.

Ⅰ. 서 론
 Ⅱ. 재료 및 방법
  1. 실험기간 및 장소
  2. 공시가축 체중
  3. 실험설계
  4. 실험사료 성분 및 배합비
  5. 사양관리
  6. 조사방법
  7. 통계처리
 Ⅲ. 결과 및 고찰
  1. 임신 단계가 채식량에 미치는 영향
  2. 임신 단계가 저작 및 휴식행동에 미치는 영향
  3. 임신기간 경과가 반추행동에 미치는 영향
  4. 임신 단계가 음수 및 배설행동에 미치는 영향
  5. 임신 단계가 채식율, 반추효율 및 저작효율에 미치는 영향
 Ⅳ. 요 약
 Ⅴ. REFERENCES

• 변병현(경북대학교 축산학과) | Byung Hyun Byoun
• 이재훈(경북대학교 축산학과) | Jae Hun Lee
• 이상무(경북대학교 축산학과) | Sang Moo Lee Corresponding author