초록
This study was performed to evaluate the rate of twin pregnancy and parturition in dairy cows. Calving records of Holstein dairy cows from 1998 to 2009 comprising Goyang and Paju cities herd with 20,990 calving events representing 820 twin births were used to evaluate twinning rate, calf sex ratio, periods of pregnancy and complication after parturition in single and twin births. Overall, the reported twinning rate was 3.9% in Holstein dairy cows. Rate of bicornual pregnancy (75%) was larger than that of unicornual pregnancy (25%) among cows having twin. Regardless of parity, the greatest twinning rate was observed in fall season from September to November. Calf sex ratios (male, M; female, F) were 48.0% FM, 28.9% MM, 21.5% FF and 0.9% mummifications for twin calves. Parturition type among cows having twins included normal (4.7%), premature (66.9%), delayed (9.2%), abortion (18.4%) and mummification (0.8%). The period of pregnancy in twin pregnancy (mean 272.6 days) was shorter than single pregnancy (mean 278.1 days). The retained placenta after parturition was over fourth times such as twin parturition (34.8%) higher than single parturition (8.5%) and the abomasal displacement was over two times such as twin parturition (10.2%) higher than single parturition (4.9%). The distribution of twin pregnancy with parities was high rate during the 2~3 parities. The prevalence of complication such as retained placenta and abomasal displacement with twin parturition revealed higher than single parturition.
