With the upcoming calving season the threat of calf scours should always be given some consideration. Calf scours is the condition that baby calves in the first month of life deal with when they get a severe case of diarrhea that may be life-threatening. It is an infectious disease that may be caused by one or more of viruses, bacteria and tiny parasites.
For a number of years the approach to calf scours control was centered on the bugs that were identified as being involved in their cause. E. coli bacteria, Rota and corona viruses, cryptosporidia and others were all identified. Vaccines against the bugs and antibiotics to treat them were often at the center of control programs. Despite all this good science, results of these approaches were sometimes disappointing.
Finally, a group of scientists in a bit of a new field had a look at calf scours. These scientists belong to a field called epidemiology. This is the study of disease patterns. Prior to these studies, the thought tended to be that scours occurred on a farm because it was unlucky enough to have the scours-causing bug land on their farm.
When a group of researchers at Washington State University did a detailed study on calf scours they discovered a very interesting thing. When they looked hard enough, they found that nearly every farm had many or all of the scours causing organisms. Some of these farms had severe scours problems while others had none.
This finding caused the main researcher, Dr. Dale Hancock to make the following statement, “Saying that calves have scours and that cryptosporidia is the cause is like saying that the barn burned down, and oxygen was the cause.” Of course, the barn wouldn’t have burned if there had been no oxygen, but what were the odds of that? It can also be said that if the wind is blowing to provide additional oxygen, it will speed up the burning of the barn.
So if being unlucky enough to get the scours bugs on a particular farm isn’t the big cause of scours, what is? Many factors have been studied but several important ones include: 1) the age at which a calf gets exposed to scours agents; 2) whether the calf has had enough colostrum or not; 3) whether calves are getting enough nutrition; 4) the dose of exposure to the disease agents; 5) a healthy immune system for the calf due to having had good nutrition during gestation; and, 6) other stresses on calves such as wet or cold.
A very important concept has emerged from this line of research. The concept involves the pattern of transmission of the scours organisms to the calves. Many of the agents are probably present in most every cow herd. But since the cows are very immune to these bugs, the numbers that are being passed by the cows are very small. This means that, at the beginning of the calving season, the calves don’t get infected until they are several days to weeks old.