When choosing breeding stock of either sex always check the underline. The position and number of teats is very important in both male and female as the male will pass the teating on to his daughters.
This video shows a pig with bad front legs. Her legs are turned outwards at the knee. Always choose breeding animals with strong, straight front legs and good feet. (the back legs on this pig are not too bad) She also has a 'rose' in her coat. This may be passed on to her piglets and is not a desirable trait in a breeding pig.
This litter of piglets vary in size and stature. When selecting breeding stock, look for piglets who are strong and well developed. Short legs, a strong body, a straight back and a 'leg at each corner'. Well developed hams indicate a piglet who has been feeding well from the sow. Size is immaterial at this age but good development is important.
This pig's back slopes sharply from hip to tail. She 'drops away' towards the tail. Nice pig but this spoils her.
4b.) This pig has a nice straight back with his tail set 'high'. If choosing a boar for breeding it would be particularly important to have a good strong back end as by nature of his job, he will need it.