Why no animals?
Animals spawn in daylight or high levels of light on the surface, and your valley is probably darker than the surrounding flatlands, with less grass as well. The shallow daytime light and the high probability that you're surrounded by stone walls is probably the cause of your troubles.
Try moving your home to the top of the valley, and look around in grassy areas - animal mobs spawn more frequently in large stretches of grasslands, but you'll also find them in almost any other terrain as well.