Withholding food for 20-hours before a hunt doesn't compute for dogs that are worked hard or hunt multiple days in a row. There aren't enough hours in the day.
I have a 13-month old GSP that eats 30% more food this time of year and barely maintains his weight. Dogs have to eat to work, so a light meal in the morning followed by a handful of food every few hours during the hunt. An hour or two after the hunt he can eat at will until he hits the total I want. At any point during the day I'll spike his food as necessary to entice him to eat. I'd be in the same place as Tbjohn in the OP, looking for a treat recipe, if I didn't have success spiking my dog's regular food with simple ingredients.
