In Alma 5:59 we find Alma declaring: "For what shepherd is there among you having many sheep doth not watch over them, that the wolves enter not and devour his flock? Brant Gardner notes that there is a good deal of sheep imagery in this text, and this passage appears to appeal to common knowledge of the problems of shepherds.
This is an imagery that is completely at home in the world of the Bible, as attested by several references (see, for example, Ezekiel 22:27; Luke 10:3; Acts 20:29). So Alma's words about sheep and wolves might have been understood because of imagery on the brass plates.
However, wolves and sheep are not well attested for the New World, in particular the Mesoamerican area. John Sorenson notes that while this is generally true, we may not yet have all the necessary data:
The Eurasian sheep is not supposed to have been in pre-Columbian America either, yet real sheep's wool was found in a burial site at Aholula, Puebla, Mexico, in an archaeological setting that gave no other indication of dating after the Spaniards arrived. This lone specimen doesn't take us far toward a literal reading of the Book of Mormon term sheep, but perhaps we should keep this door too ajar a little. (John L. Sorenson, An Ancient American Setting for the Book of Mormon, p. 296)
[Brant Gardner, "Book of Mormon Commentary," [http://www.highfiber.com/~nahualli/LDStopics/Alma/] Alma5.htm, pp. 40-41]