What is good for the goose, is not always good for the gander. There are a few manures that should not be used, primarily those of meat eaters. According to Cornell University, "Homeowners should not use any manure from dogs, cats, or other meat-eating animals, since there is risk of parasites or disease organisms that can be transmitted to humans."
The most common sources of manure are horses, cattle, goats, sheep, rabbits and poultry. Below is a guide showing how manures measure up, nutrient-wise. While all animal manures are good sources of organic matter and nutrients, it's impossible to make a precise analysis, mostly because bedding materials vary so much. For example, manure with straw or sawdust will have a different nitrogen composition than pure manure. But it's useful to know whether the manure you're using is rich or poor in a particular nutrient such as nitrogen.
As you review the list, don't be misled by the N-P-K numbers that suggest manure is less powerful than chemicals. It is actually far better because it contains large amounts of organic matter, so it feeds and builds the soil while it nourishes the plants. This is one of the primary ways that organic fertilizers have a leg-up on chemical ones.
Still, many gardeners can't resist comparing the numerical amounts listed below with what they read on packages of synthetic fertilizers. Unfortunately, the values of manure and organic fertilizers in general, are often based on the relative amount of nitrogen (N), phosphoric acid (P) and potash (K) they contain. While these are important elements, "it is misleading to make a direct comparison between farm manures and chemical fertilizers on the basis of the relative amounts of N-P-K," says Jerry Minnich, author of Rodale's Guide to Composting.
Just like we need to eat to maintain our health, soil needs continual replenishment of its organic matter to decompose into humus. Humus helps create a rich, moisture-retaining soil and makes nutrients available to plants.