A transportation trailer having a moving floor including a plurality of reciprocating slats for loading/unloading materials into the trailer. The trailer includes a system for warming the moving floor when the materials transported in the trailer freeze on the slats in cold weather. Using the pre-existing hollow structure of the slats, a stream of hot fluid or a hot fluid pipe is run inside the slats for thawing the frozen materials for unloading the trailer. The hot fluid may be provided from a hot fluid source on board of the trailer, for thawing the frozen materials while the trailer is on its way to the unloading site, or may be provided separately at the unloading site.