It all depends on what country you are modelling. My guess is North America, so why not have a meat packers factory with the livestock outside in pens? The livestock could be brought in by rail and unloaded into cattle pens to await their fate. Then it is just a matter of running the livestock up a ramp into the meat packing plant.
Other ideas for an American railway (or should that be railroad?) include a reefer stage icing platform, a feed and grain warehouse or a lumber mill.
If the railway is in steam age Britain why not model Garsdale's famous stockaded turntable? This structure was in the middle of nowhere, but was built for pilot engines to turn round. The pilot engines were tacked onto the front of Scottish expresses to give more power up the Long Drag, a tough gradient. The stockade was built round it to stop engines being blown over by strong winds. Incidentally, you can still see the Garsdale turntable (minus stockade) on the Keighley & Worth Valley Railway (did I ever tell you I am a member?:hehe: )
Best wishes,
Padster