Do female centaurs have two sets of mammary glands?
Your question just let me figure out something I’ve wondered about for decades.
Of course they only need one set of functioning mammary glands, where a foal would be able to reach them.
And that’s why there are no nipples on the other set. They are purely decorative. It’s obvious when you think about it!
I would suppose Fillies to have 6 teets. 4 under two to top.
Horses only have two underneath.
Yes, but centaurs have six, it is a chimeric hexagonal understanding. The number of the beast and all that. A Centaur usually has three foals.
A Centaur Stallion has two (human) teets. Dormant, but nevertheless nipplage. The female is thrice.
Okay… but where is that? If you’ve got a short but upright centaur foal, neither the usual ‘horse’ spot nor the usual ‘woman’ spot seems terribly convenient to suckle at. Centaurs of any size don’t seem especially bendy, so being able to reach down and put your face under mom’s horse body…
Damn, this is gonna bug me now. 
I think the torso mammaries make more sense since the mother can easilly lean down at the neck/waist junction.
I’m fairly sure that a centaur wouldn’t have more than one (or occasionally two) babies at once. generally the larger a mammal is, the fewer offspring they have at once.
There was an SNL sketch where a centaur was being interviewed for a job and the interviewer (played by Christopher Walken) couldn’t stop asking rude non-job-related questions.
Example:
“How do you wipe your ass?”
In one of CS Lewis’ Narnia books, a Centaur points out that he has two stomachs - a horse and a human one - so he eats hay and grass before tucking into a full english as well.
So I am going with functional horse and human nipples - for the two different stomachs of the foal.
Si
My first thought is that nipples have no obvious connection to stomachs.
My second thought is that the CS Lewis explanation doesn’t really make much sense either. Better to have one long digestive tract that shares some of the properties of human and horse - possibly multiple stomachs, for the same reasons that certain grass-eating animals have them, (do horses have multiple stomachs, or is that just cows I’m thinking of?)
Um - I think thats what Lewis was suggesting. A Centaur has one mouth and one anus (a single digestive tract) with a man-stomach and a horse stomach. Man-food goes in one stomach, and horse-food in the other. Both need to be fed to meet the nutritional requirements of a half-man/half-horse.
A foal will need feeding via both stomachs - so the mother needs to provide human milk, via breast nipples, for the human stomach, and horse milk via udders for the foals horse stomach.
Si
Horses have one stomach, cows (and other ruminants) have four stomachs (rumen, reticulum, omasum, abomasum, the last one being the equivalent of our stomach).
One thing to note about that, calves, while they are still drinking milk, only use one of their stomachs (abomasum). All the milk is directed away from the rumen and goes straight to the abomasum. As they grow older and start eating grass, that shortcut stops functioning and the food starts to pass through all stomach compartments.
Centaurs would then need only one stomach, because only one stomach is needed to handle milk.
Newborn centaurs are much more precocial than human infants, and the human torso is more the size of a three-year-old, with attendant muscle development. A centaur cannot carry her offspring around the way a human mother can; the newborn must be able to stand and walk within hours of birth.
Therefore, given the size and developmental specifics, the human torso mammary glands are the ones that are functional, and are almost exactly at the proper height for the foal.
Never mind stomachs, I think the key issue is the mouth. A human mouth would nurse much more easily from a human nipple (Romulus and Remus notwithstanding). I’m also assuming that gestation would be longer for centaurs, since they don’t have to deal with the narrower upright-walking pelvis that humans have, so the centaur baby would be able to walk shortly after birth. (Can you imagine trying to cradle-hold a baby centaur? Awkward.) Anyway, presumably the baby could reach the human nipples, especially if the mother bent forward a bit.
(I love this board.)
Haven’t you ever seen a horse foal feed? They’re much shorter than mom, for one, and they just slip their head sideways under her belly and go at it. It looks a little awkward, but it works. I think a centaur foal would be flexible enough to manage it. After all, centaurs wouldn’t have evolved to their present form if they couldn’t feed their young!
As I progressed through the thread, I was heading toward this conclusion, too, despite my earlier brilliant reasoning that led to my earlier brilliant post.
But if this were the case why don’t the upper breasts have nipples? All the brilliant anatomical drawings that Dr. Disney has provided make it perfectly clear that there are no nipples. And since there are no extant illustrations of the lower teats (a sad omission in an otherwise exemplary scientific record) I’m going to assume that, however they are configured, they must be suitable for suckling by the young centaurs’ mouth. Because otherwise centaurs would have died out. Q.E.D.
I stand by my earlier assertion. The upper breasts are ornamental (for the purpose of attracting males) and the lower breast are the functional ones.
Yeah, me too! 
Perhaps the female nipples are recessed, only to engourge and be visible when in estrus.
I’m not able to provide a cite at this time. commasense, because I must keep my Google at work on “SafeSearch” and am thus blocked from searching up images of “Fantasia centaur nipples,” but I think we had at least one glimpse, despite the rampant austinpowerisms of the filmed sequence…
(edited to remove superflous observation regarding the harpies of Bald Mountain)
It’s really funny if you’re doing Christopher Walken’s voice in your head while reading it.