Diarrhoea (scours) is the most common disease problem in the young unweaned calf. It is estimated that it affects, in varying degrees, over a third of all calves during their rearing period and is responsible for roughly half of all calf deaths (MDC & NADIS).
Calves are born with no protection against scour causing microorganisms. They must therefore receive initial protection via colostrum from their mother, known as passive immunity. After this they must develop their own active immunity.
Many things can negatively affect this process, some of which cannot be controlled. In approximately a quarter of all scours the pathogen cannot be identified and could be resistant. This can result in vaccinations and antibiotics being less effective.
However other things are within the control of the farmer such as hygiene and colostrum intake. Bedding for newborn calves should be dry; kneeling down on the bedding without feeling dampness is a good test for this. Adequate, good quality colostrum is essential for calves to get off to a good start. They should receive at least 2 litres as soon as possible after birth. Additionally colostrum should be tested to ensure it is good quality.
Protection for the newborn calf can be increased by using Provita Protect, an effective proven oral probiotic to control calf scour by 83%. It can also be used to bridge the immunity gap. This gap in the immune system occurs when the passive immunity from colostrum has decreased, and the active immunity from the calf itself has not increased quickly enough, see diagram. Most veterinarians recommend that quality vaccinated colostrum is fed to calves for the first two weeks, however on most dairy farms this does not happen.