The wood (pine) shavings are the "carbon content" in terms of composting chicken litter. Let mother nature take her course, but if one insists on speeding up the decomposition process, then one would need to add additional water into the equation. Obviously doing this can create its own set of problems, the least of which is an unhealthy environment for the chickens themselves if done directly in the coop and if too much moisture is introduced too quickly. I use the deep-litter process and am amazed at how long 4" of pine shavings lasts in my well-ventilated coop.
When my birds defecate onto the pine shavings (which decompose rather quickly by nature), the process of decomposition (composting) begins almost immediately. The birds stir the poop-laden litter up daily when they scratch for treats, which aerates the mix and ensures that the bedding dries out quickly. By doing this chore themselves, the birds maintain their house in an ammonia-free state and earn their keep by creating decomposed organic matter that I can use all I can get for the gardens! It's a win-win situation.
Keep in mind, if you will, that chicken coop litter will always be in various stages of decomposition using the deep litter method since the "mix" of manure/carbon is always changing and because time marches on. I got around this somewhat and temporarily by placing the litter from the brooders into my compost tumblers to which I attend to daily. The litter, table scraps and lawn clippings in the tumblers break down quickly and I can attain finished compost in about one month's time. My coop litter (compost) will need to be fully collected come fall and then I can regulate the proper moisture to organic matter ratio without risk if "side effects" to my birds. Adding more moisture will vastly accelerate the full composting of the litter.
Finally, for effective composting to take place, the proper (or nearly so) recipe should be achieved utilizing appropriate amounts each of nitrogen (the likes of manure, greenery, table scraps), carbon (browns, including softwoods, dried leaves, twigs, dried hay and straw, etc.) and moisture. Excessive moisture can result in an unpleasant odor, but does yield one pleasant and useful side benefit- "compost tea," which can be used in flower beds and for watering other plants as well!
Just my four-cents worth. lol
