I have seen a lot of counties that have special classes for county raised animals, and some just show them with everything else and reward the highest placing county bred animal. I grew up in Louisiana and most of the Parish Shows and all of the district and State Shows gave awards and premiums for the high placing Louisiana Bred animals.
As far as the school district show in Houston, that is fairly common here in TX, especially with the Ag Programs in the cities and suburbs. It is really common for the schools here to have Ag Barns, and most of those calves are raised in those barns and never go home. The purpose behind this is educational and providing the kids with the opportunity to have a livestock project. In those settings most of the kids have no place to raise an animal, have no experience with animals, and it is all to intimidating to their parents to go out and try to find a calf, pig, lamb, or goat. So the Ag Teachers go out and purchase a group of animals, ussually steers or pigs, they keep the cost down so that they can charge a nominal fee for the kids to participate.
I dont know how all of them do it, but I know one school district that does it with hogs, the kids sign up and I think they pay $100. They have to sign up before the Ag Teacher goes to buy. So if he has 25 students sign up he knows he has $2500 to spend. He typically goes to show pig producers and picks their lower end and sometimes to Duncan and buys pigs out of the parking lot. He naturally spends an average of $100 per pig, and does his absolute best to get pigs that are fairly similar in conformation at that point. Then the kids draw numbers and pick their pig in the order they drew. The pigs are tagged before the draw. The students can take the animal home if they have a suitable place to raise it, or they can raise it at the schools Ag Barn(which most do). The Ag Teacher helps when needed but it is the students and their families responsibility to choose what to feed, purchase the feed, and feed the animal. At the end they have a show, and with the similarity in the animals at the beginning it really comes down to how good of a job the student did raising and preparing the animal. I personally think this is a great opportunity for students to learn. I Have even known of some instances where it lead to the students parents purchasing them projects for future county shows and even majors. I think in that siutaiont it provid3s a great opportunity for students who may not otherwise have it