Here is a section I found on an article about fertilizing a garden.
The "Read More" link takes you to an extensive article about feeding the plants it different ways.

"The plant food in "green" or fresh manure is not available, and does not become so until it is released by the decay of the organic matters inside. Now the time possible for growing a crop of garden vegetables is limited; in many instances it is only sixty to ninety days. The plants want their food ready at once; there is no time to be lost waiting for manure to rot in the soil. That is a slow process- especially so in clayey or heavy soils. So on your garden use only manure that is well rotted and broken up."

Read more: Manure Vs. Fertilizer- Which Should be Used in Your Organic Vegetable Garden?
Under Creative Commons License: Attribution

Also as someone already said, fresh manure can "burn" you plants.