Do you like horse racing?
I love horse racing, when it is done ethically. I used to work at a feed store where we made deliveries to some of the biggest equestrian facilities in FL 
Do horses work well in humid hot air?
They can, but they have to be monitored. Humidity and heat breed mold like no other, if they eat moldy feed they can die same day if they aren't cared for and there is much suffering involved
Wow, that doesn't sound very good for their health at all.
Hay
Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, particularly for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep. However, it is also fed to smaller domesticated animals such as rabbits and guinea pigs. Even pigs may be fed hay, but they do not digest it as efficiently as herbivores.
Hay can be used as animal fodder when or where there is not enough pasture or rangeland
by Smarty Jones' stable foreman, "Big Bill" Foster: "Number one in horse racing, you have to have the horse. Number two, you have to know what to do with the horse once you have him. A lot of people in this business have a lot of horses, and never made it because they broke them down. It happens a lot. Mismanaged. Mistrained. All because people want to be in the limelight. Which is where we're different. We don't want to be