Re: : Newmarket saleyards
You're correct, the cattle and sheep sidings where were the supermarket, and also the curved block of flats that follows the showgrounds line trains now stand.
The following links fro Mark Bau's excellent VR site will (hopefully) take you to the Newmarket track plan. http://www.victorianrailways.net/signaling/completedia/flem1915.html
There are some photos, I think on the Public Records Office website, that show the unloading of animals.