The Collaborative International Dictionary of English v.0.48:

cattalo \cattalo\ n.
   hardy breed of cattle resulting from crossing domestic cattle
   with the American buffalo; it yields leaner beef than
   conventional breeds; it is called also beefalo.

   Syn: beefalo.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

cattalo
    n 1: hardy breed of cattle resulting from crossing domestic
         cattle with the American buffalo; yields leaner beef than
         conventional breeds [syn: cattalo, beefalo]