Chicken Flavored Dog Biscuits

1 package Dry yeast 1/4 cup Warm water 2 cups Chicken stock 3-1/2 cups Unbleached flour 2 cups Whole wheat flour 1 cup Rye flour 2 cups Cracked wheat or wheat germ 1/2 cup Dry milk 1 tsp Salt 1 Egg 1 Tbsp Milk Preheat oven to 300 degrees F. Beat egg with 1 Tbsp milk. Dissolve yeast in 1/4 cup warm water. Add to chicken stock. Combine all dry ingredients. Add chicken stock mixture. Knead on a floured surface for about 3 minutes, working into a stiff dough. Roll out to a thickness of 1/4". Cut into bars, or shape with a cookie cutter. Brush with egg/milk wash and place on cookie sheets. Bake in 300 degree oven for about 45 minutes. Turn off heat and leave biscuits in oven overnight.