Please read how too little or too much moisture in your birds litter can seriously affect the health of your birds: http://www.poultryscience.org/psa06/abstracts/psabs62.pdf. (excerpt) "....Many producers underestimate the detrimental effects of ammonia. The human nose is able to detect ammonia levels near 15 parts per million (ppm) but will lose even this level of sensitivity with long-term exposure. Ammonia concentrations of 50 to 110 ppm can cause the human eye to burn and tear and induce possible health risks to farm workers. EPA has set human exposure standards that should not exceed 25 ppm per 8 hours or 35ppm per 15 minutes of exposure. Chickens are also sensitive to ammonia. Prolonged exposure to high levels (50 to 100 ppm) can result in keratoconjunctivitis (blindness). Obviously, when ammonia levels are high enough to blind birds, production is seriously affected; however, ammonia levels of just 25 ppm have been found to depress growth and increase feed conversion in broilers. In addition, a greater incidence of airsacculitis, viral infections and condemnations have been linked to ammonia levels at this concentration. .................... Litter that is too dry and dusty can also lead to problems such as dehydration of new chicks, respiratory disease and increased condemnations. Ideally, litter moisture should be maintained between 20 to 25 percent. A good rule of thumb in estimating litter moisture content is to squeeze a handful of litter. If it adheres tightly and remains in a ball, it is too wet. If it adheres slightly, it has the proper moisture content. If it will not adhere at all, it may be too dry................................ As time passes, used litter can become seeded with pathogens that affect bird performance. High humidity, warm temperatures and high pH favor the proliferation of pathogens in the litter. .Avian influenza, laryngotracheitis, gangrenous dermatitis, gumboro, reovirus, bronchitis and botulism are several of the more serious viral and bacterial diseases known to spread easily in contaminated litter. In addition, fungi that produce mycoses or mycotoxicoses have been isolated in broiler litter, and there is some evidence that these may cause increased mortalality............... Parasites, such as round worms, tapeworms and coccidia, are also a potential problem in reused litter. Wet litter further aggravates coccidiosis by providing the proper environment for oocysts to sporulate, thereby increasing challenge levels to which birds are exposed.............."