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.
These older calves may not be noticed to have scours at all as their case is very mild. But they begin to shed organisms in much bigger numbers into the environment. These bugs then get to calves that are born later in increasing number and at ever earlier ages. The next round of calves may just get dirty tails and be a little depressed.
As the process proceeds scours causing organisms build up in great numbers. Many calves with diarrhea now badly contaminate the calving area. Cows that are ready to calve may get the diarrhea fluids on their teats so that their newborn calves get a huge dose of organisms into their mouths within minutes of birth. This huge dose at a very early age results in calves that get so sick that they may die quickly without aggressive treatment.
Three major approaches to dealing with this scours scenario should be applied:
1. Move cows that have not calved into a separate calving pasture. An intensive version of this is called the Sandhills calving system. This Nebraska system is designed for large herds of cows and involves moving uncalved cows out every few days. Eventually the old calves are mixed with the next older group(s) so that a large number of pasture and feeding groups stays manageable. But even splitting the herd once can be very helpful in breaking the scours organism build up pattern.
2. Practice sanitation in the calving pasture. Rolling out hay in a different location every day moves cattle around so that calves and cow’s udders spend more time in uncontaminated areas. This delays the time it takes for calves to get infected and lowers the dose of disease-causing organisms that they consume. While calving cows in barns may be a necessity to prevent exposure when it is really cold, calving outside nearly always results in less exposure to disease organisms.
3. Have good health management systems in place to keep calf immunity as high as possible. Working to be sure all calves get a good feeding of colostrum is especially crucial
In time of high calf prices, spending extra effort to avoid losses due to scours is especially cost-effective.