This writer has been around livestock for 25+ years. Every spring and summer you have to go through bouts of scours with the calves. The most common causes have been Nutritional Scours, E. Coli Bacteria Scours, Coccidia, and mothering ability for the cow. Usually there were no problems until the rain really started pouring down and water started sitting in the calving lot. This would be cleaned up using the tractors to dig small trenches to let the water run off, and by pushing the mud off to the side of the lot to try to keep bacteria from growing and spreading.
E. Coli bacteria spreads very quickly through the herd, so if you aren't keeping up with it daily you'll end up with 50-75 percent of the herd coming down with it. Coccidia is very common as well. It is a virus that calves along with many other animals get. This writer has had dogs with this as well and it is the same treatment for E. Coli, just keep pushing fluids.
Nutritional Scours comes from the cow having very rich milk and the calves drinking more than they need of it. Generally you can push electrolytes through the calves and give Sulfa tablets to correct this. The biggest issue with calf scours is making sure the calves have plenty of electrolytes. If they do not, you will lose calves due to dehydration.
Calf scours develop as well through the lack of mothering ability from the cow. This problem usually occurs with first-calf heifers, meaning this is the first time the cow has had a calf. Sometimes first-calf heifers do not produce the required amount of milk needed for healthy growth and nourishment for the calf. If this happens, you may need to get a milk replacer for the calf. It has been found using raw eggs as a supplement is also helpful. Raw eggs add more protein to the calves diet.
The quality of milk also depends on the cow's quality of colostrum. Every calf needs colostrum as soon as it is born. If a calf does not get this colostrum you may lose the calf. Raw eggs also help with this, if you have a cow that is not producing enough colostrum. You can usually go to the vet to get frozen colostrum, or if you have a milk cow, her very first milking after the calf is born will have colostrum that you can save and put into the freezer.
If a calf is not running around and feeding regularly chances are it is sick. Common symptoms are fever, weakness, separating themselves from the herd and laying down, as well as dehydration. You can tell if a calf has dehydration by pinching the skin on the calf's neck, if it does not immediately go back to the body of the calf then the calf is dehydrated.
Never mix water and milk together to give the the calves while they have scours. The water will prevent the milk from transforming into curds. If the milk does not curdle in the calves stomachs they will not be able to digest the milk. When using electrolytes give the calf orally a little over two quarts one to three times per day. You can also feed one or two raw eggs with each electrolyte cycle.
Please make sure that you take care of all of the healthy calves before moving on to provide care for the sick ones. This will help prevent the spreading of calf scours. Always wash your hands immediately with antibacterial soap after you handle these calves. If you do not, you could spread the cause of the scours to yourself, your family, or household pets.