Abstract
The purpose of this study was to investigate the effect of inbreeding and other phenotypic factor for stillbirth in Japanese Black cattle. We used 2,878 calving records from January 2009 to February 2012 in Hokkaido and their pedigree records. Analysis was conducted by logistic regression analysis with fixed effects (season, sex, twin, parity, gestation length, inbreeding coefficient of calf). Average stillbirth rate was 2.12%. From logistic regression analysis, twin, parity, gestation length and inbreeding affect stillbirth. Especially, odds ratio of twinning birth is high (vs. single birth is 10.66). For the effect of parity, class of 3th-4th parity is low risk of stillbirth (vs. 1st parity is 0.28). Risk of stillbirth become high when gestation length is less or more than 11 days from average (289 days). Also calves have over 15% inbreeding coefficient, stillbirth risk increase.
