Chicken health benefits of deep bedding

April pointed me toward some great information about deep bedding (aka deep litter) on Robert Plamondon's website.  I had thought the main benefit of the system was for the garden, capturing all of those nutrients in chicken manure that might otherwise leach away, and later decided that deep bedding also has the benefit of keeping your chickens warm in the winter.  But poultry scientists from the 1940s turned up another major benefit --- increased chicken health.

When done correctly (more on how to do that in a later post), deep bedding is a bit like compost --- you build up a community of beneficial microorganisms that keeps the ecosystem running.  As readers of Teaming with Microbes know, a healthy soil food web cuts down on plant pathogens since the good microorganisms are able to outcompete the bad.  A similar effect may be taking place in deep litter, but in this case the good microorganisms outcompete the protozoa that cause coccidiosis.  Meanwhile, low levels of coccidiosis protazoa in the deep litter may act like a vaccination, inoculating your chicks with low levels of the disease that their immune systems can fight off and then become resistant to.  However the specifics work, the poultry scientists showed that chicks raised on well aged deep litter had a lower mortality rate than chicks raised on young deep litter or without deep litter.

The scientists also found that deep litter helped counteract the effects of a poor diet.  They put one set of chickens on a vegetarian diet that they knew lacked essential ingredients for avian health and another set of chickens on a complete diet.  Some chickens from each group were raised on deep bedding of various ages, and others were given fresh bedding regularly.  Once again, the deep litter birds did better, with growth rates and survival rates of malnourished birds on deep litter nearly matching those of well nourished birds.  Once again, the causes of deep litter's effects on chicken health is unclear, although I've read (and can come up with) a variety of possibilities.  Robert Plamondon suggests that vitamin B12 is produced in the deep litter through bacterial fermentation, while I wonder whether microorganisms (like worms) attracted to the deep litter aren't scratched up by the chickens to supplement their diets.  I wouldn't be surprised if the chickens even ate fungi growing in the deep bedding, getting some nutrition that way.

The authors concluded: