They ship other breeds (they actually brag about shipping 52 weeks a year). I wonder though if those breeds they dont are ones they buy the eggs of. I know a lot of hatcheries dont actially house all the breeds they sell
They're active members of the group that represents each type of poultry industry in Texas for advising the various state agencies and maintaining the integrity and safety of the TX Ag industry overall, and they're all alumni of the same college at A&M that I graduated under, so I know a little more about them than most would I guess.
I'm pretty sure they don't sub out. For one, the Salmonella and AI NPIP certs in Texas are a major PITA, they'd have to be paying a subcontractor a premium to keep that up. There were two other large hatcheries waaay back in the day in that area, and I know they bought one of them, so I assume they also bought the other as well, which is probably how they have that much volume. I can't remember the other one, but I have a poster from the other, circa 1925, from the old Horning Bros. Hatchery in Cameron.
So my guess is that they either use those birds for hybrids, supply the statewide 4-H with them**, or use them themselves to hatch and use for next year's breeders. There was a hatchery last year I saw do that, where Ameraucanas and Legbars were only available part of the season and Easter Eggers (chick down sexable) the other part.
**Because TX does not allow birds from out of state to be shown, and I think the kids all have to get them from the same place so that it's about how they are as a caretaker and not genetics or their parents' ability to buy from a top breeder. I know that's how it is with the broilers, they all have to be ordered from A&M for the show season, and A&M may very well get them from Ideal. (One of my co-worker's kids had their rabbits killed by a predator a few weeks ago, and I offered some of my birds, she said they had to put in all that stuff months in advance and there were a bunch of rules, so that's why I assume it's probably something like the broiler thing for the show chickens, but IDK.)