Yes, it is true. This is because Calol® can safely mobilise the body calcium (from bones) of the cow, so she can correct her own problem. This action is much quicker than actual calcium absorption from the gut.
I find Calol® does not pour as quickly as some other products.
This comparison is very much overrated, but Calol® is deliberately thick for safety reasons. Milk fever cows can have difficulty swallowing liquids. However action is much more rapid and there is more than enough in a bottle for one treatment. Do not waste time squeezing out the last drop, keep it and store for future use. If you use a lot you will eventually get a free bottle. I hope the suppliers do not read this!