Preheat oven to 350°F (175°C).

Brown the sausage in a pan, drain on a paper towel, and crumble into small pieces.

In a large bowl, combine the whole wheat flour, all-purpose flour, baking soda, baking powder, salt, and oats.

In a separate bowl, mix together the eggs, oil, yogurt, brown sugar, and white sugar.

Stir in the shredded zucchini.

Add the wet ingredients to the dry ingredients.

Stir until just combined.

Fold in the crumbled sausage and toasted ground walnuts.

Pour the mixture into two greased loaf pans.

Bake for 50 to 60 minutes, or until a toothpick inserted into the center comes out clean.

Let cool slightly before slicing.

Serve as is or brown slices in butter.