Hiya,
Not that this is the last word, but I've never heard of only feeding oil
eight months out of the year, or of gut irritation caused by feeding
fat. It is true that if a large amount of fat goes through the gut when
you're unaccustomed to it, the gut will be unable to absorb all of it.
This will result in diarrhea, which could potentially be irritating to
the gut, but this is a short-term overload situation, not a long term
thing. Although I'm unaware of any formal studies that have determined
any long term effects of feeding fat, I do know of quite a few people
that have been feeding high fat levels for some time and only got good
results out of it. And believe me, these folks pay attention to what
shape the poop is in, which I would think would be a likely effect of an
irritated bowel. I've also assisted at several necropsies of horses
that incidentally were fed oil as part of their diet and the guts looked
fine---the horses were insured and death unexpected, so the DVM was
THOROUGH and I was taking notes for him.
If you still have access to the vet that told you this, I'd be
interested in hearing more, or maybe some of the DVMs on the list know
something about it. I've never heard of it, but that don't mean taint
necessarily true.
Susan