The aim of this study was to compare ultrasonic measured traits (Eye muscle area : EMA, backfat thickness : BF and marbling score : MS) of Hanwoo cows by months of age and periods around 1st calving. The data used in this study were taken 2,636 cows which were measured from 20 months old to 28 months old and within 5 months around 1st calving. According to comparison of cows' month of age, ultrasonic measured EMA, BF and MS were not significantly different between 21 months old and 26 months old, 21 months old and 25 months old and 23 months old and 27 months old, respectively. According to comparison of periods around 1st calving, ultrasonic measured EMA, BF and MS were not significantly different between -45 days and 30 days, -15 days and 75 days, -105 days and 90 days around 1st calving, respectively. The selection of cows could be possible based on the phenotypic ultrasonic measurement performance if the traits are measured between 23-month old and 25-month old and between - 15 days and 30 days around 1st calving.

• 최태정(농촌진흥청 국립축산과학원) | Tae Jeong Choi
• 최연호(농촌진흥청 국립축산과학원) | Yun Ho Choy
• 조광현(농촌진흥청 국립축산과학원) | Kwang Hyun Cho
• 최재관(농촌진흥청 국립축산과학원) | Jae Gwan Choi
• 이승수(농촌진흥청 국립축산과학원) | Seung Soo Lee
• 박미나(농촌진흥청 국립축산과학원) | Mi Na Park
• 김시동(농촌진흥청 국립축산과학원) | Sidong Kim
• 조용민(농촌진흥청 국립축산과학원) | Yong Min Cho
• 구양모(한국종축개량협회) | Yang Mo Koo
• 박병호(농촌진흥청 국립축산과학원) | Byoungho Park Corresponding author