Not having a spouse or significant other, the question of would you or wouldn't you doesn't even apply to me. I'd get 'em.
HOWEVER, having BEEN a spouse three times previously, I do have an opinion on how to handle the situation in which the OP finds himself:
Communication is everything in a relationship. A conversation - even one way - like this might be appropriate:
"Honey, I know you don't want me to get any more chickens, but I just got rid of 3 and I really want to add Speckled Sussex to my flock. So, I'm going to get a couple of them - the flock won't be any larger than it was before. I hope you understand how this is important to me, even though it's "just chickens." You'll see how pretty they are and they are good layers, too. See you in a bit....." and head out to go get your chickens.
Upon your return, be prepared to discuss the matter further.