If you teach your calves to drink from a bucket, much of the nutritional value of the milk is lost since it goes into the rumen, which is under developed in young calves (it does not begin to develop until calf eats solid food) ~ they function as a single stomach animal. Feed with a bottle, as the sucking reflex creates a direct pipeline to the true stomach.
Even after the calves start digesting hay and grass in the rumen, calves continue to digest milk in the true stomach. Digestion of milk in the true stomach is very important to health and growth of the calf. Is only accompolished by sucking/ sucking reflex.
I also think that calves that are bottle fed are less likely to scour. Some will say the are less likely to get lung infections as they are not inhaling milk through their nose.
Bottle feed. Aways clean bottles and nipples after feeding. We wrote names/ numbers on bottles. Each calf had its own bottle and only its bottle. Nipple stayed with the bottle.