Even the most well-managed beef herds periodically lose an animal.
Though the causes range from illnesses to natural disasters, the result
is the same. The producer has to deal with a carcass.
Carcasses are usually sent for rendering, but under some circumstances,
this may not be an option.
The current concern about BSE and the feeding of animal protein to
cattle may also have an impact on rendering services.
Producers who deal with carcasses on the farm have traditionally chosen
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burial or burning, but there is another alternative for disposal –
composting.
A mature cow carcass will decompose completely, with the exception of a
few small bones, in about six to eight months.
At that time, the residue can be processed with a manure spreader.
Composting is a natural process in which the carcass is decomposed by
microorganisms.
True composting takes planning. Simply covering a carcass with manure
is unlikely to promote successful decomposition.
Composting begins with the selection of a suitable site.
The location should be easily accessible with equipment, located away
from water sources and streams and inaccessible to live cattle.
A plastic sheet of six mil. poly about 3.7 metres wide is placed on the
ground and covered with approximately 45 centimetres of compost
material.
The carcass is placed on top of this base and the body cavity is opened
to speed decomposition.
The carcass is covered with enough composting material to bring the
final height to 1.6 m.
The composting material that is packed around the carcass is the key
element in the process.
To ensure optimal growth of microorganisms, its carbon-to-nitrogen
ratio must be high enough to balance out the high nitrogen content of
the carcass.
The ideal mix is 50 percent manure and 50 percent old feedstuffs, straw
or sawdust.
Sawdust is the preferred component because it has the ability to absorb
water and it contains the optimal particle size to allow aeration.
The moisture content of the composting material should stay between 50
and 60 percent.
If it feels moist but does not drip when squeezed, it contains the
right amount of moisture.
Too much moisture causes odours and increases the risk for runoff from
the pile. If it is too dry, the bacteria will not flourish.
Aeration of the compost pile provides oxygen to fuel microbial growth.
Good aeration is evident when composting material contains particles
between 30 and 130 mm in diameter.
Oxygen penetration can also be boosted by mechanically turning the pile.
Temperature is another important consideration in the composting
process.
Microbial activity declines if the temperature is too high or too low.
The ideal temperature is between 43 C and 66 C.
With composting material at least 30 cm, the pile is insulated so the
preferred temperature range can be readily maintained.
Temperature can be monitored by inserting a thermometer about a metre
into the pile.
If the temperature is too low, the pile should be turned with a front
end loader and the carcass covered again with compost material.
It takes about three days for the temperature to rise to 63 C.
After about two weeks, the pile will be about one-half its original
height.
It should be turned at this point and periodically over the next few
months to maintain the desired rate of decomposition.
Jeff Grognet is a veterinarian and writer practising in Qualicum Beach,
B.C.
