http://www.backyardpoultrymag.com/issues/5/5-2/herbs_for_spring_eggs_and_breeding.html :
Creating wood charcoal and ash from native wood can be a very beneficial and important supplement for your poultry. Charcoal can absorb toxins and is capable of absorbing up to two hundred times its own weight. Animals in the wild would come across charcoal after forest fires or lightning strikes and they would be drawn to these places to consume charcoal. Charcoal has minimal nutritional value, but research suggests that animals consume it for its medicinal, toxin-binding properties. The charcoal is also a laxative and so then can work twofold and move the impurities it absorbs out of the body. If worms or worm ova are present, it can to some degree help move them out of the body as well.
Your poultry will also eat wood ash as well as charcoal. Wood ash has a very nice texture to aid in dust bathing and adding it to their dust bathing pits to eat and dust in will give your poultry a double-benefit! Wood ash is highly soluble in vitamin K, followed by calcium and magnesium. Vitamin K is useful for blood clotting in poultry.
Charcoal can be made from dry, clean branches or tree stumps burned slowly in a deep pit. Or throw an un-split log on a bonfire or fireplace as the fire is winding down in heat and intensity. Slow burning is essential to charcoal making. You can damp down a fire that is burning too quickly with some water. You can build an outdoor bonfire with brush, and leave the remains of a fire pit where chickens range, allowing them to eat it free choice.
Having a woodstove makes it quite easy. By morning the fire dies down quite a bit and there will be embers or coals at the bottom of the woodstove. Local wood is preferred, like walnut, oak and locust. Before stoking the fire back up again for the day, smooth the coals out. At this time, the ash settles to the very bottom and chunks present themselves. If the fire has gone completely cold, you can pick out chunks of charcoal barehanded and they are ready for use immediately. If, in the morning, you have hot coals, then of course take care removing good chunks to use. Most of us who have woodstoves also have an accessory kit of sortsthe poker, brush and small shovel. Use that small shovel to remove what you wish to use and place those chunks in a safe place to cool completely. In a few hours or less the charcoal chunks can be handled safely. If you have young or inexperienced pets or children, consider the careful placement of the hot coals. Charcoal is a good spring "internal" cleaning, but in reality, charcoal and ash can be beneficial year-round.
Starting with healthy hens, keeping them healthy during the mating, egg laying, and brooding process will keep those little chicks hatching all season long. And, in turn, will insure the chicks have a good start to a long and productive life themselves.
Susan Burek is owner of Moonlight Mile Herb Farm in Willis, Michigan. Find Susan's website at
www.moonlightmileherbs.com. Laura Corstange is owner of The Wishing Tree in Plainwell, Michigan. Find Laura's website at
www.wishing-tree.com. Both herbalists advise on Blue Moon Forum, an herb forum for people and critters, specializing in poultry, at
www.members.boardhost.com/bluemoon.