Abstract: There is provided an enclosed air conditioned trailer for transporting living fowl. The trailer includes a ceiling, first and second side walls, a front wall, a rear opening having a door attached thereto, and a bottom platform. A floor is located above the bottom platform, forming a space therebetween. At least one elongated air handling duct is located in the space. One end of the duct is attached to an air conditioning apparatus located near the front wall. The other end of the duct is located near the rear opening of the trailer. The floor forms the top of the duct. A plurality of openings are provided along the top of the duct so that air can pass from the duct into the inside of the trailer above the floor. The duct is tapered so that the velocity air flow from the holes is substantially equalized for the length of the duct. An outside air intake valve is provided and is opened in response to the detection of high CO2 levels on the inside of the trailer.