This is one of those things that is going to be argued again and again and again and again . . .
When a calf is born, the abomasum is significantly larger than the rumen. An adult bovine has ratios of about 80% rumen, 5% reticulum, 8% omasum and 7% abomasum (% of total stomach volume). But at birth the figures for rumen and abomasum are almost reversed.
This is because of the oesophogeal groove (also known as the reticular groove) which pops up on these boards quite frequently, which ensures that milk goes directly to the abomasum, rather than the rumen where it will
a) be broken down completely giving very little nutrition to the calf, and
b) introduce bacterial into the rumen which ordinarily would not be there - rumen bacteria is ingested when the calf begins to nibble grass, and the population slowly grows and the rumen develops in conjunction with this. By introducing the 'wrong' bacteria, the 'right' bacteria are slower to develop.
When a calf drinks from a bucket, his head points down and he 'gulps' rather than 'sucks'. The oesophogeal groove does not open, and the milk enters the rumen, where it has the effects mentioned above ^^. The sucking action and the head tilted up to nurse is what opens the groove.
As a side point, it is also often asked on these boards "I've got a poddy calf, and I'm giving it milk. Do I need to supply water and feed?" and the answer is a resounding YES!
By withholding green feed, roughage etc from a calf's diet, you will delay development of both the rumen and the population of rumen bacteria, resulting in a growth and development setback for the calf.
I'm actually suprised at the riot caused by the bucket/bottle calf issue. Here in Australia, we call them poddy calves (or poddy lambs, kids, foals). But the terms bucket and bottle are also used. BUT, really, its just a management choice isnt it? They are all orphans, who cares what you call them?
Going back to the original post, a poddy is a great way to introduce your kids to showing! Hope you and they have fun and keep us updated with some photos when you get them