Feather meal is a byproduct of processing poultry; it is made from poultry feathers by partially grinding them under elevated heat and pressure, and then grinding and drying. Although total nitrogen levels are fairly high (up to 12%), the bioavailability of this nitrogen may be low. Feather meal is used in formulated animal feed and in organic fertilizer.
Worldwide, more than 25 billion chickens are used for human consumption. Feather meal is made through a process called rendering. Steam pressure cookers with temperatures over 140 °C are used to "cook" and sterilize the feathers. This partially hydrolyzes the proteins, which denatures them. It is then dried, cooled and ground into a powder for use as a nitrogen source for animal feed (mostly ruminants) or as an organic soil amendment.
Containing up to 12% nitrogen, it is a source of slow-release, organic, high-nitrogen fertilizer for organic gardens. It is not water-soluble and does not make a good liquid fertilizer. It can be used to:
When adding it to a garden as a nitrogen source, it must be blended into the soil to start the decomposition to make the nitrogenous compounds available to the plants. As an organic garden fertilizer, it is not synthetic or petroleum-based.
Issues
A 2012 study found that feather meal contributes to inorganic arsenic exposure to humans whether it be in the form of animal feed or organic fertilizers.
An analysis of feather meal across the United States also shows a variety of drugs that chickens are exposed to. Included are antibiotics such as fluoroquinolones which have been banned but are still included in the food supply. Other drugs include Prozac, antihistamines, fungicide, sex hormone norgestimate, and caffeine. The bioacculumative effects of these variety of pharmaceuticals are of concern to human health.