In pigs, dominance hierarchies can be formed at a very early age.
Domestic piglets are highly precocious and within minutes of being born, or sometimes seconds, will attempt to suckle.
The piglets are born with sharp teeth and fight to develop a teat order as the anterior teats produce a greater quantity of milk.
Once established, this teat order remains stable with each piglet tending to feed from a particular teat or group of teats.
Stimulation of the anterior teats appears to be important in causing milk letdown, so it might be advantageous to the entire litter to have these teats occupied by healthy piglets.

Using an artificial sow to rear groups of piglets, recognition of a teat in a particular area of the udder depended initially on visual orientation by means of reference points on the udder to find the area, and then the olfactory sense for the more accurate search within that area.
In pigs, dominance hierarchies can be formed at a very early age. Domestic piglets are highly precocious and within minutes of being born, or sometimes seconds, will attempt to suckle. The piglets are born with sharp teeth and fight to develop a teat order as the anterior teats produce a greater quantity of milk. Once established, this teat order remains stable with each piglet tending to feed from a particular teat or group of teats. Stimulation of the anterior teats appears to be important in causing milk letdown, so it might be advantageous to the entire litter to have these teats occupied by healthy piglets.
Using an artificial sow to rear groups of piglets, recognition of a teat in a particular area of the udder depended initially on visual orientation by means of reference points on the udder to find the area, and then the olfactory sense for the more accurate search within that area.
Domestic pig