MADSION, Wis. (AP) – Checking the health of 2,500 show cows arriving in Madison for the World Dairy Expo is a tall task.  The University of Wisconsin-Madison School of Veterinary Medicine says more than 60 volunteer students are ensuring the process runs as smoothly as possible.  As scores of trailers roll into the Alliant Energy Center for the expo, the students are examining health care papers submitted by veterinarians who have inspected the cattle.        Professor Sheila McGuirk says some of the cows have been on extremely long journey from points around the U.S. and Canada and need to be checked in quickly. Cattle manager Laura Herschleg says last year the cows came from 37 states and seven provinces.  The World Dairy Expo is Oct. 2 to 6.