If a young calf is scouring, get it off milk FAST.
Milk is an ideal feed for young animals and equally ideal for bacteria.
For a day, give it only glucose in water at the rate of one desertspoon glucose in 1 pint water. This will provide sufficient energy for the calf and discourage the bacteria. If it's scouring really badly then add a couple of pinches of salt to each feed as well.
Next day give it half milk/half glucose. Goats milk would certainly be good.
If it seems better by third day, go back to normal feed.
Adding garlic powder to all it's feeds will also help against bacteria. It used to be added to one brand of milk substitute for that reason. (Don't know if they still do.)