I have to take the word of you better-informed viewers that Joe Besser was good in something. I only know him from Stooge shorts like this one that he so foully stank up. Moe, Larry, Curly, and Shemp may have been frequently immature in their behavior, but it was the immaturity of rowdy boys, not of whiny little sissies.
The only observation that I have to add about this short is that it is amusing to see that when Tony, the Wonder Horse is in profile, somebody is always standing just forward of the hind legs, to maintain the illusion that "Birdie" is a mare.
I thought she sounded like Christine McIntyre. In any case, not a plausible she-Stooge voice.
Having Joe Besser as a third stooge is a bit like the extremely nerdy Eugene replacing Kenickie or Doody in GREASE (1978), had that bizarre scenario ever taken place. Come to think of it, some of their antics with Putzie in that film were compared to The Three Stooges at the time, as I recall!
The concealment of Tony's "manhood" was, no doubt, also necessary to satisfy the Board of Censors, which was still in force (Albeit, probably in a somewhat watered down state by 1956-57!) at the time.
I really didn't pick up on who might have voiced Birdie. As Christine McIntyre had completely retired from film and TV work by the time HOOFS AD GOOFS was made, I'd say it's safe to rule her out as a possibility for having provided Birdie's voice.
I agree that Moe's not being able to retaliate for Joe's sissified fisticuffs was a rather jarring moment, not to mention Joe's sissified fisticuffs themselves, which I've seen play far better in other comedic situations, such as those with Lou Costello.
Audio looping seemed to be more common in the shorts by this time. In this short, I noticed an instance in which Larry's voice can be heard, even though Larry's lips don't move one iota! It's a rather painfully easy spot, at that!
I do agree that Moe's bit with Benny Rubin was pretty much HOOFS AND GOOFS' highlight! This short gets 4/10 from me.