1. There are two separate halachic issues: 1) whether a Beefalo (a Bison-Cow hybrid) is a kosher animal; AND 2) whether it is permitted to breed them because of a distinct isur of mixing separate animals (the “mule”) issue.
2. There should be no problem with eating a “Beefalo” since it is just a funny looking cow (as are all Bison), and they are clearly cattle with which we have always been familiar. Unlike mules, they naturally mate and produce fertile offspring. No shailoh.
3. The “zebu” was due to a person ignorant about biology asking a shailoh based on a false premise, i.e. saying that since a “zebu” is a new animal we have no experience with, do we need a separate mesorah to hold it to be kosher. If the person did his research properly before asking, the question would have been based on “a zebu is a funny looking cow from India – that is in all ways just another type of cow, not a separate species”. When one asks a shailoh, one states facts and the Rav answers on the basis of those stated facts, and if you mess up with your facts, the answer you receive is no more relevant than the misstated facts upon which the shailoh was based.