There's a an upper limit on the number of pets you can breed at once, and this limit is per-account, not per-player, similar to limit on player workorders. (The limit increases as you raise Animal Husbandry, but the total across all your characters can't exceed this character's current limit.)The per-account breeding maximum is five at a time. For example, suppose you have a maximum level Animal Husbandry breeder character. The maximum that character can breed simultaneously is five, after all the bonuses. But then you have an alternate character on the same account also pick up Animal Husbandry. Initially, you can only breed one pet at a time on that alternate—but when you do that, then the maximum your first character can breed simultaneously is four. Then, at Animal Husbandry Level 15, that second character can breed a second simultaneous attempt. When that alternate breeds two pets at once, the first higher-level character is then temporarily limited to three. The same thing happens when you have a third or more Animal Husbandry-enabled characters on your account: The maximum number of breeding attempts/gestations across all of them remains five total.