This study was conducted to report the census survey results of south Korean Chikso (Korean Brindle Cattle) distribution and to diagnose the current coat color expression patterns. Two years Chikso census showed that there were 2,413 Chikso in 2013 and 2,754 in 2014 in south Korea. Number of animals between 0 to 35 months of age was 1,632 heads in 2014 which comprised 59% of total Chikso population size. The percentages of animals between 36 ~ 71 months of age and over 6 years of age were 31% and 10% of total. Out of 2,416 animals with class numbers assessed by their coat colors, 1,249 heads (52%) were in group I (with black stripes, class no. 1 ~ 3) and the others (class no. 4 ~ 7) were in group II (1,167 heads, 48%). Among the 1,551 animals that were photographed twice in 2013 and in 2014, 226 animals were assessed different coat color class numbers, and round 90% of which were within the ages less than 48 months. The number of animals switched in coat color pattern groups over a year was 56, which was 3.6% of total number of animals on survey. And around 88% of the animals switched in group category was of the animals younger than 24 months of age. Therefore, we conclude that the coat color pattern becomes rather stable at around 24 months of age in Chikso populaion in south Korea.

The objective of this study was to identify the phenotypic relationships among calving difficulty, calf birth weight and gestation length of Holstein dairy cattle under the environment of Korea. A total of 1,834 calving records collected by Dairy Science Division of National Institute of Animal Science, RDA from 2000 to 2014 was analyzed. General linear multivariate models for calving difficulty scores (CD: 1=no assistance, 2=minor assistance, 3=two to three persons assisted, 4=more than three persons assisted, 5=cesarean section), calf body weight at birth (BW), and gestation length (GL) included fixed effects of year and season (spring, summer, autumn, winter) of births (YS), sex of calves, and parity. For GL and BW, all three fixed effects (YS, sex of calves, parity) were significant (p<0.05). For CD, the effects of YS and sex of calves were significant (p<0.05). Bull calves were born with heavier BW by 3.18 kg, with greater CD by 0.18 point and with longer GL by 0.6 days than heifer calves. The least squares mean of BW was the heaviest at the third parity (44.1 kg) compared to those at the first, the second and the fourth parities or later (41.3-41.9 kg). The least squares mean CD at the first parity was 1.74 point, which was higher than CD at the second and later parities (about 1.68 points). Phenotypic correlation (partial residual correlation) between GL and BW was 0.36. But those between GL and CD and between BW and CD were -0.03 and 0.04, almost zeros. To conclude, we observed higher incidence of calving difficulty in the first calving than in the later ones. Further investigation on the relationships between calf’s birth weight and calving difficulty is needed

케토시스 지표형질에 영향하는 환경요인을 살펴보기 위하여비유단계, 계절 및 착유시간에 대한 생산형질의 변화를 살펴보았다. 유량은 비유일수가 증가할수록 높아지는 추세를 보였고, 유지방 함량, 유단백 함량, 무지고형분 함량은 DIM1(비유초기)에서 가장 높게 나타났다. 계절에 따른 생산형질의 변화를 살펴보면 유량은 봄·겨울에 높게 나타났고, 유지방 함량과유당 함량, Acetone 및 BHBA 모두 가을에 높게 나타났다.또한 유량은 오전 착유시간이 높았고, 유지방 함량 및 유단백함량은 오후 시간대가 높게 나타났다. 환경요인에 따른 생산형질 및 케토시스 지표형질의 함량은 모두 유의적 차이를 보였으며, 분석모형을 설정함에 있어 위의 환경요인은 고려되어야 할 사항이다. 생산형질과 케토시스 지표형질의 상관관계 분석 결과 유량의 경우 Acetone 및 BHBA의 수치가 증가할수록 감소하는추세를 보였고, 유지방 함량은 반대로 Acetone 및 BHBA의수치가 증가할수록 증가하는 경향을 보였다. 비유단계와BHBA의 농도는 음의 상관관계를 보인다는 기존의 결과와 반대로 분석결과 양의 상관관계를 보였다. 유전력은 착유일5 ~ 20일에서 0.03 착유일 21 ~ 40일은 0.05 착유일 41 ~ 60일은 0.04 착유일 61 ~ 80일은 0.08 착유일 81 ~ 100일은 0.04의 유전력을 보였다. 이는 비유 5일째에 준임상형 케토시스의발병률이 가장 높게 나타난다는 기존의 연구결과에 비추어 볼때 유전력이 낮게 추정된 것으로 사료되며, 이는 1산차의 분석 자료수가 충분치 않은 결과로 추정된다. 케토시스 저항성개체 선발을 위한 유전평가모형에 적용가능한 선발지수를 개발하기 위해서는 여러해의 축적된 자료를 이용한 분석이 필요한 것으로 판단된다.