Risk factors for stillbirths and mortality during the first 24 h of life on dairy farms in Hokkaido, Japan 2005-2009

Abstract

This was a retrospective cohort study using data from the insurance scheme provided by the Japanese Mutual Aid Association (NOSAI). The population of interest comprised all cattle born on NOSAI-client farms in the Japanese prefecture of Hokkaido, Japan for the period 1 April 2005-31 March 2009. The outcome of interest was whether or not at least one calf was stillborn, had died during delivery or died during the first 24 hours of life for a given calving event, termed first 24 h mortality risk.A mixed-effects logistic regression model was developed to identify explanatory variables associated with first 24 h mortality risk. The final data set comprised details of 1,281,737 calving events on ..