The study was carried out with 13 Mexican Hairless (MHP) and 21 York-Landrace (Y-L) fattened pigs, randomly distributed in 4 treatments: 1) MHP under total confinement, 2) MHP in pasturing conditions, 3) Y-L in total confinement and 4) Y-L in pasturing conditions, all four groups were fed ad libitum . Morph metric growth in 63 days old pigs showed significant differences (p<0.0001) between breeds; however, at the end of the study (175 days old) significant differences were observed (p<0.05), both between breeds and between productive systems for the following variables: height at withers, hind- and fore- cane perimeters and snout length; indicating that the feeding system caused some hypertrophies in the organs mostly exercised. Results on the percentage of ileal apparent digestibility showed significant differences (p<0.001) between breeds and between productive systems too, whereas in the total apparent digestibility, differences between feeding-productive systems were only significant in the MHP. Results indicate that the MHP is a small size animal with thin limbs, these pigs show a great instinct for forage consumption but are unable to take advantage of this since they can not digest fiber, which ends with the myth that swine autochthonous breeds are able to digest fiber.