Tear bread into chunks and whirl in a food processor to make fine crumbs. Measure 2 cups and put in a large bowl.
Squeeze sausages from casings into bowl. Add ground turkey, egg, milk, onion, sage, salt, black and white pepper, and cayenne. Mix well.
Pat meat loaf mixture into an oiled or nonstick 5- by 9-inch loaf pan.
Bake in a 350° oven until meat loaf is firm to touch in center, about 1 1/2 hours.
Serve hot, or let cool, then cover and chill until cold, at least 3 hours. Or store, chilled, up to 2 days. Run a knife between meat and pan rim. Invert meat loaf onto a platter. Cut into thick slices.