Risk Factors for Intramammary Infection at First Calving in Ontario Dairy Heifers

Abstract

It has been established that a significant number of heifers are infected prior to, and at calving, with both minor and major mastitis pathogens. Ontario is no exception, and has a significant proportion of heifers calving with quarters infected with mastitis pathogens including Staphylococcus aureus, coliform bacteria, environmental streptococci and coagulase-negative staphylococci. Because of the negative impact such infections may have on future milk production and udder health, it is important to identify risk factors for these intramammary infections (IMI) so that attempts can be made to control them. It is particularly important to investigate risk factors for S. aureus IMI, since infected heifers must experience a mode of transmission other than spread at milking time.