What was the first live-action movie to feature a talking animal, and did the film predate the first live-action televised appearance of a talking animal?
Francis the Talking Mule first appeared on film in 1950:
This pre-dates Mister Ed's TV debut by a decade.
1. The Wizard of Oz featured a talking lion in 1939, but that was obviously an actor in a costume so I assume we're not going to count it.
2. You might be able to find an earlier film with a talking parrot if you know any very early pirate movies. Probably also not what you meant.
Predating all of the above, but not necessarily considered features (if the length of the film is of concern) the Dogville Comedies featured talking dogs in a variety of situations. These shorts began being shown in 1929, not long after the advent of sound in motion pictures. These can often be seen on TCM, or you can can see an example here on Youtube.
Laurel & Hardy's Dirty Work has a scene where Oliver turns into a monkey and talks. Not sure if it's the first one, but it sure is an early one (1933).