drinking water on the raceday

Question
Hi sir. on the race day, my horse's groom told me that after the horse eats its feed, he would provide water, let the horse take few sips of water and then he removes the water bucket. may i know why? shouldn't the horse drink too much of water on the day he's going to race?

Answer
hi   that is a practice followed at the race track on race day. sometime even the night before they will take away any hay if the horse is a bleeder. they want to draw the horse to make sure the horse is not full of feed and water when they race.  thanks ED HESS