It would be helpful if we knew what the actual Spanish version was supposed to be.
This Spanish language site repeats many of the items found in pezpunk’s first link.
For this item, they have:
- El eslogan sobre el pollo de Frank Perdue se tradujo al español del siguiente modo “se necesita un hombre potente para que un pollo sea afectuoso”.
[The slogan about Frank Perdue’s chicken “it takes a strong man to make a tender chicken” was translated into Spanish in the following way “one needs a {potent/powerful/virile} man in order to make a chicken affectionate.”]
However, this other Spanish site translates the item more directly:
- El eslogan de Frank Perdue el hombre - pollo [?], “Hace falta un tipo duro para hacer un pollo tierno”, se distorsionó terriblemente en otra traducción al castellano. Una foto de Perdue con uno de sus pájaros apareció en las vallas de todo México con un texto que explicaba que “Hace falta un tipo duro para hacer un pollo despierto”.
[The slogan of Frank Perdue the chicken-man, “A {hard/tough} guy is needed to make a tender chicken,” was terribly distorted in another Spanish translation. A photo of Perdue with one of his birds appeared on billboards throughout Mexico with a text that explained that “A {hard/tough} guy is needed to make an [alert/woken-up] chicken.”]
Neither of the Spanish phrases offered seem to me ones that might have been created by an English speaker relying on an English-to-Spanish dictionary, but rather ones created by a Spanish-speaker trying to translate the anecdote from English. Therefore these do not seem to be an authentic examples of the original Spanish slogan.
If the story were true, I would expect to find a consistent version on Spanish websites. These merely seem to be Spanish translations of a story that was originally in English.