HEALTH-STATUS OF PREWEANED DAIRY HEIFERS IN THE UNITED-STATES

The first national estimates of mortality and morbidity for preweaned dairy heifers in the US were generated from monitoring heifers from 90 6 operations in 28 states prospectively using a daily diary card syste m. Results indicated that the cumulative mortality incidence risk from birth to 8 weeks of life was 6.3% with a peak of 1.9% during the firs t week of life. Season of birth was significantly associated with cumu lative mortality incidence risk, and mortality risk was highest in the periods January to March and October to December. Cumulative incidenc e risk of diarrhea to 8 weeks of age was 24.6% with a peak of 15.4% du ring the second week of life. Diarrhea incidence risk varied by region , with the West having the highest incidence risk (30.5%) and the Nort heast the lowest (19.2%), as well as by herd size, with the smallest h erd size having the lowest reported incidence risk of diarrhea to 8 we eks of age (18.8%). Other reported 8 week cumulative disease incidence risks included listlessness, 10.0%; respiratory disease, 8.4%; dehydr ation, 4.1%; lameness or joint problems, 1.1%.