Convection
Temperature can be transferred by conduction, convection or radiation.
In case of convection, heat is transferred only by the circulation or movement of a heated liquid or gas (fluid). A typical example of convection is the movement of water in a boiling pot: at the bottom the water is closer to the fire and is heated, increasing its volume and rising, therefore the water in the surface descend, generating a circular movement.
In the case of farms, this fluid is the air that surrounds the animal: when this air is heated, increases its volume and rises, so the animal is surrounded by new and cooler air.
For that reason, when there are airflows, the cooling is greater.