The thread below about Turkey trains had me search on the subject. Here is what I found:

From about 1890 to 1960, shipping live chickens and other birds by rail in special "henhouses on wheels" was commonplace. The cars featured wire mesh sides (which were covered with cloth in the winter to protect the occupants) and a multi-level series of individual coops, each one fitted with feed and water troughs. A human attendant traveled on board in a central compartment to feed and water the animals along the way. The cars were also equipped with a coal stove that provided heat for the center of the car.

The concept is thought to been the brainchild of William P. Jenkins, a freight agent for the Erie Railroad. Jenkins collaborated with a Muncie, Indiana poultry dealer by the name of James L. Streeter on the design of a specialized car designed solely for transporting live fowl. The Live Poultry Transportation Company was formed about the same time that the first poultry car patent was issued (U.S. Patent 304,005 , issued August 26, 1884). By 1897, the company had 200 units in operation.[23]

The Continental Live Poultry Car Company, a rival concern, was founded in 1890. Continental thought to dominate the market by offering larger cars, capable of transporting as many as 7,000 chickens in 120 coops, but the oversized cars failed to gain wide acceptance, and the firm closed its doors after just a few years in business.[23]