Buuuuut steering back to the thread's topic a sec. Just in case anyone reading feels alone. Yeah, being an olfactophile in general, I'll admit to enjoying the scent of animal mouths. Especially as OP says, the way this scent changes as you pull away and the air hits it in those first seconds. I can't scientifically explain what exactly happens there. Something about the normal flora bacteria and what they do when exposed to open air in those fleeting moments, as the two of you pull away, how their saliva scent morphs to something even better. Dunno. Dog has a much better nose than me. So ask a dog. Or a microbiologist.
But yeah. Love me a few huffs of that oral 'normal flora' in various species. Catching smell of their breaths when we're kissing, heavy petting makeouts, ratcheting up the passion by suckin' face, swapping spit, sharing breath, lapping and being lapped. So much attraction begins in the nose and mouth, both for them and us. Scent foreplay and tongue passion. It's what it's all about, man. I've even been known to just stop what I'm doing, swoop down and rake my nose along his jowl at random thru the day, just to take a hit of his salivary scent. Its almost a form of greeting in my pack, another way we have of saying "Hey there, you. C'mere and give me summa that." lol
Not so much cattle when they're ruminating tho. Chewing cud is a bad time to go kissing cows. Basically vomiting into their own mouths and burping up rumen gas while doing it. Smells bad and yes this is why they're blamed for methane -- it's not farts, it's belches; cows actually don't fart much, being four-stomached ruminants, the digestion is very complete. The only time they get gassy out the tailpipe is when they eat something they shouldn't have. Also, bovine tongues are like iron files and plenty strong. Take the hide right off a man, you ain't careful. They also tend to stubbornly keep licking the same damn spot on you. They're not much for spreading the love around.
Finally, jack donks win hands down in all things mouthy. As kissers, nibblers, biters, oral passion in general. Nothing else in the animal kingdom has the natural talent here like donks. From full-fledged frenching and tongue wrestling indefinitely til you have to pull away raw-gummed and sore-jawed, to the expert neck and shoulder biting, there just ain't nothing out there that knows a good game of make-out like donks. Their mouth game is second to none.
That is all. Carry on.