Successful copulation depends upon the female’s receptivity. Sexual receptivity will occur during a period termed estrus, in which physical and behavioral changes occur in a sow due to the surge of the hormone estrogen. Her receptivity corresponds with her high level of fertility. She will have increased interest in the boar, swollen vulva, nervous activity, male sexual behaviors (mounting, nosing, and pursuing other females), changes in vocalizations, and increased vaginal mucous.
The boar will respond to these signs and proceed with his courtship beahaviors. He will bite her neck, nuzzle her rump and back, grind his teeth, and foam at the mouth. A noticeable increase in vocal activity (grunting, chattering, chomping) and motor activity will occur.
There is a significant amount of nasonasal or nasogenital contact to determine if pheromones are present (in urine).
He may have several false mounts. He will also nudge her flank to test for lordosis (the physical immobilization of the female by locking her joints to prepare for mounting, a reflex observed only in estrus). The female will only display this behavior if she is in estrus.
The following shows a sow that is not receptive to the boar.
Copulation ranges anywhere from 5 to 20 minutes in length. A boar will normally mate with the same female multiple times over a period of 1-2 days.
This serves as a resting period for the boar.
Stage 2 Parturition and Teat Seeking
Stage 2 of parturition in swine lasts from 2 to 3 hours, varying depending on litter size.
Since the sow does not lick her young to stimulate blood flow and nursing, instinctual teat seeking is crucial to the piglet’s survival. Piglets are attracted to warm surfaces, and any protrusions on the sow’s body. After finding the teats, the piglets will proceed to move from one to another until the optimal teat is located. These tend to be on the anterior of the sow. The following two videos show birth of a single piglet and teat seeking behavior.
Piglets compete with each other for the best teats. Born with needle-like teeth, the piglets bite and push their way to the valued teats, with the largest piglet normally getting first choice. After the initial conflict is over an order is developed and piglets return to certain teats when feeding.
Displaced piglets often struggle to feed amongst peers, and constantly fight to get milk. They will nurse at irregular times and teats, consume inadequate milk, and therefore have low weight gain.
At birth piglets cannot control their internal temperature efficiently, therefore they huddle to maintain warmth.
Pigs are naturally very curious and explorative. This tendency is showcased by their drive to root, sniff, and nibble at grounded objects in their environment. If afraid of a novel object, they will flee. However they will investigate if not pursued.
The pig uses aggressive actions as a means to establish his dominance over the competing pig. This allows him privileged access to the food resource.