Don't ask me - ask Roger Waters, David Gilmour, Richard Wright, Nick Mason and their avant-garde co-composer, Ron Geesin. They put it out there, I just happened along.
The 23:44 Atom Heart Mother suite in 6 parts from the album of the same name was another one of those songs that I played obsessively in my dorm room. (Only Shine On You Crazy Diamond and its 9 parts is longer.) It was profoundly comforting at a time in my life when very little was. It had an intoxicating quality that was helpful in numbing my anxieties, and in fact I often played it as I was going to sleep.
Co-creator Ron Geesin was an experimental musician who claims some his personal influences were Victor Borge, The Goons and Surrealism. That would explain a lot ... The suite was complete with an orchestral score, a smoking David Gilmour guitar solo that may or may not have been a slide guitar, a hefty component of brass, a choir, numerous inexplicable sound effects, both vocal and otherwise, and no real lyrics to speak of.
The album was actually Pink Floyd's first to go #1 (in the UK). Alan Parsons (later of the Alan Parsons Project) was one of the recording engineers on this, as he was for Abbey Road and Dark Side of the Moon. Most of the members of Pink Floyd have been quoted as saying they didn't like much about the album after it was finished, and from what I can tell, people who knew about it either loved it or hated it.
I think this is one of those songs where you just had to be there for it to make sense. I can't imagine how anyone hearing it today for the first time would react to it. I'm pretty sure the cow was part of the overall allure. The story goes that the group wanted the album cover to be as un-Floydian and ordinary as it could possibly be to throw people off so their photographer went out into the countryside and took a picture of the first thing he saw. Makes about as much sense as the song itself!