note 5-composting chicken carcasses v2

   Meat Chicken Technical Environmental Note 5
   Composting Carcasses in Open
         Bays and Piles
                                                Eugene McGahan and Robyn Tucker
                                     FSA Environmental - http://www.fsaconsulting.net
                                                                      February 2002
Introduction
Composting carcasses in open bays and piles is an environmentally and biologically
safe alternative if performed correctly. A major advantage is the production of a
nutrient rich humus-like material that can be used as a fertiliser and/or soil
amendment. However, composting facilities need to be designed and managed
correctly to avoid any bio-security issues.

Basic Elements
Moisture

The optimum moisture content for carcass composting is around 50%. The compost
should be moist, but not soggy and you should not be able to squeeze moisture from
it. If the compost is too dry (less than 40%) the process slows, as there is insufficient
moisture for bacteria survival. If the compost is too wet (above 60%) the process is
likely to become odorous as the water excludes the oxygen needed to maintain an
aerobic environment. Decomposition by aerobic microorganisms produces very little
odour compared to the highly odorous organic acids and hydrogen sulphide
produced by anaerobic digestion.

Co-composting material

Adding a co-composting material to the carcasses provides additional carbon, which
helps to maintain a high level of microbial activity. On meat chicken farms, the most
readily available co-composting material is the spent litter, provided it does not
contain excessive moisture. Advantages of adding a suitable co-composting material
include:
   •   By surrounding the carcasses with a co-composting material, the potential
       scavenging by animals will be mostly eliminated.
   •   A porous co-composting material maintains oxygen levels in the carcasses
       and promotes escape of the ammonia produced by digestion, which would
       otherwise inhibit microbial activity.
   •   Excess liquid released by the decaying carcasses will be absorbed.

Carbon, nitrogen and oxygen

Carbon (C), nitrogen (N) and oxygen (O) are key elements in the composting
process. Without an appropriate balance of carbon and nitrogen, limited microbial
growth will inhibit the decay rate. Optimum C:N ratios are around 25:1 to 30:1.
Although composting will proceed with C:N ratios of 10:1 to 50:1 the process will be