Factors Associated with the Incidence of Retained Placentas

Factors associated with the incidence of retained placentas in Holstein cows were determined from records of 298 calvSngs at the South Dakota State University research farm from 1968 to 1972.The incidence of retained placentas was 7.7% for cows with single births and 35.7?0 for cows with multiple births.Calving number and incidence were unrelated when multiple births were removed.Incidence was lower in August through November compared with other seasons.Gestation length was 3.3 days shorter for cows with retained placentas while calf birth weights were similar.Incidence of genital infection was higher in cows with retention although subsequent breeding efficiency was similar for all cows.Milk and fat production were higher from cows with retained placentas.Sex of the calf had no influence on incidence of retention or any of the variables.