Happy Trail Dog Biscuits

1 1/2 cups all-purpose flour
1 teaspoon salt
1 1/2 cups whole wheat flour
1 cup rye flour
1 large egg
1 cup old-fashioned oats
1/2 cup vegetable oil
1 cup cornmeal
1 3/4 cups beef broth
1/4 cup liver powder

Place oven rack in upper third of oven. Heat oven to 300 degrees F. Line a cookie sheet with foil.

In a large bowl, mix the dry ingredients. Add egg, oil and broth. Mix with a wooden spoon to make a soft dough. The dough should be soft but firm enough to roll out. If the dough is too moist, add a little more flour; if too dry, add a little water.

On a floured surface roll out the dough to 1/2-inch thickness. Cut in 3 1/2 inch dog bone biscuit shapes with a cutter or pattern. If using a pattern, flour the top of the dough first. Place 1 inch apart on prepared cookie sheet. Re-roll scraps. With a skewer, prick a line of dots down centers, halfway through. Bake for 2 hours.

Turn oven off and let the biscuits stand in the oven overnight to dry out and harden. These can be stored in plastic bags at room temperature for up to 3 months.