The castrated animals were subjected to orchiectomy procedure on the seventh day of life.Immunocastrated animals received two dosages of Vivax, which is a vaccine based on a synthetic analogue of GnRH coupled to a large carrier protein. It was applied subcutaneous and the first dosage was given at 60 d before slaughter (pigs were 80 days old) while the following at 30 days before slaughter (pigs were 110 days old).