Planning to prevent diarrhea and scours in calves

By Gary Sliworsky
OMAFRA Rep.

In consultation with your veterinarian, producers should begin planning a program to prevent diarrhea or scours in calves about 2 months before the start of calving. In calves, scours is usually caused by any of several infectious agents, and often is caused by more than one of these causes acting together. The bacteria, viruses and protozoa that cause diarrhea are usually carried by adult cattle who contaminate the barn with their manure.
The balance between the calf’s ability to resist infection and it’s exposure to the infectious agent causing diarrhea determines whether it develops scours or not. Scour prevention programs are made up of strategies aimed at increasing the calf’s ability to resist the infection and at reducing the calf’s chances of becoming infected.
For newborn calves, antibody in colostrum or first milk is the most important source of immunity. When colostrum is fed within 18 hours of birth, the antibody in colostrum is directly absorbed from the intestines and transferred to the calf’s bloodstream. Antibody in colostrum also works within the intestine to block infection by the bacteria and viruses that cause diarrhea. Many calves become infected with scour-causing bacteria and viruses within a short time after birth so ensuring that they get colostrum soon after birth is an important part of all scour prevention programs.
There are several ways to improve a calf’s immunity to scours. Vaccinating pregnant cows or heifers boosts the antibody that is transferred to the calf in colostrum. There are also vaccines and products that contain antibody against some causes of diarrhea. As with colostrum, the greatest benefit from these products is obtained when they are given within a few hours of birth. All these strategies will work only against E. coli, rotavirus or coronavirus. They won’t work if the scours is caused by something else and they can’t work unless you are able to make sure calves get treated or get colostrum within a few hours after they are born.
You can reduce exposure to the infectious agents that cause diarrhea by maintaining clean, dry calving areas. If a scouring problem develops, moving calving to a new area may reduce chances of newborn calves becoming infected.
If you want to determine the cause of scours in your situation, contact your veterinarian.