In 1987, there was an interesting presentation
from a turkey operation in the Midwest that
was composting its litter between flocks as a
means of reducing pathogens and recycling
the litter. So intrigued by this program, I
repeated the study with broilers. One-year old litter
was stacked for three days to allow it to self-heat and
this was compared to the untreated litter as well as
new pine sawdust bedding. In this preliminary study,
broilers started on the composted litter had the best
body weights of all treatments and the initial bacteria
load was similar to fresh pine sawdust. Excited about
the potential, several of our poultry companies were
contacted about doing a demonstration on this
procedure. At that time the industry felt there were
adequate quantities of bedding for cleanouts and our
health programs did not warrant this added effort by
our growers.
Over the past 20 years there has been growing
interest in this procedure with limited adoption in
some parts of the country. The process goes by many
different names; composting, windrowing,
pasteurization, and biological heat treatment. Once
stockpiled, many litter pathogens are reduced or
eliminated due to the elevated temperatures, the high
ammonia levels, and the heat-tolerance microbes in
these windrows.
In fact, research conducted by the University of
Delaware, Auburn University, and Louisiana State
University suggested this process eliminates
coliforms and Salmonella. It reduces clostridium
perfringens, total aerobic bacteria, and total anaerobic
bacteria by 50%, 10-30%, and 60-80%, respectively.
Some initial results from Delmarva suggest it helps
break some disease problems on farms such as
dermatitis. The procedure also is used to inactivate
many types of virus in litter such as laryngotracheitis
and avian influenza. Growers and companies that
have implemented this program rep011 improved bird
health and performance and a significant reduction in
darkling beetle populations. Depending on the
method of composting, it may reduce ammonia levels
in the subsequent flock and either reduce or eliminate
the need to crust-out houses. Some have implemented
this program as a means of improving poultry health,
others to reduce bedding replacement cost, while
some areas use it as a waste management reduction
strategy.
The timing may be right for the Delmarva poultry
industry to seriously consider this program for the
following reasons. Due to closure of sawmills and
competition for our bedding, we have limited
availability of local, low-cost, quality bedding
materials for our industry. Our bedding supplies have
been supplemented with re-processed wood chips,
some of which may not be the best quality. Although
a new Delmarva plant to produce pine shavings will
come online soon, it too will not be the cheaper
sawmill by-products (i.e. sawdust and shavings) we
have used for years. Given the disease challenges and
reduced performance when reusing litter for years
due to limited bedding for more frequent cleanouts
and higher cost, composting may provide an
opportunity to safely recycle litter. If the disease and
ammonia challenges of used litter can be managed
via composting, this may provide a waste
management opportunity for our region.
Instead of total cleanouts every two to five years
at times of the year that may require appropriate
storage facilities or approved methods for stockpiling
litter, we might minimize these challenges with
timely, partial, yearly removal of litter. By "cutting
the centers" from the house at a times that better
sequences with proper timing of land application, we
can avoid some current and future environmental
challenges. In the coming years, expect to see greater
regulatory pressures associated with outside
stockpiling of litter, spillage around houses, and land
application of litter.
Windrowing litter has been done with grader
blades on tractors, skid-steer loaders and specially designed
equipment such as the Brown Bear unit.
For Delmarva, grader blades may not be a viable
option. Forming a single windrow down the center of
the house using a skid-steer loader is an option and it
has been used the past year to help break some types
of chronic health issues in houses. With this method,
the cake is added to the mix for the added moisture.
Although it will require crusting the house when the
piles are re-spread, the volume of cake removed is
greatly reduced. Piles formed by this method tend to
be slower to heat compared to the aeration
equipment.
Windrows formed with the aeration equipment pulverize the litter,
cake and hardpan;
aerate and form the
compost windrows. It
eliminates the need to
crust-out houses and
have appropriate
storage of the caked
litter. It also avoids
any uncontrollable
spillage outside
houses associated
with crust removal.
Depending on house
width and litter
depth, two or three
windrows are formed
immediately
following bird movement. With this method, the goal
is to achieve 1300 F or greater within the first two
days and to maintain these windrow temperatures for
a minimum of three to five days. The optimum litter
moisture is .....35% but adequate temperatures are
achieved with lower litter moistures. Afterwards, the
piles are spread out with a grader blade or skid-steer
loader.
There are some challenges with in-house
composting of litter between flocks. There must be
adequate time between flocks to execute this
procedure. At this time, in-house composting may not
be an option or needed for some growers and
companies. Ideally, the practice should start following
a total clean out with the litter reconditioned
thereafter. There is a potential for high ammonia
levels in the next flock when deep, built-up litter is
windrowed for the first time. Windrowing litter in
warmer weather when ventilation rates can be
increased, turning the windrows at least once prior to
spreading, and using
higher rates of litter
treatments should
reduce this concern.
To date, we have
limited windrowing
equipment to perform
this procedure
on an industry-wide
scale. Two of our
clean out contractors
have purchased
windrowing
equipment and will
start offering this
service. Finally, the
cost of windrowing
and re-spreading
litter is higher than conventional crusting. The Delaware Nutrient Management Commission has
funded the University of Delaware to conduct a
controlled study to validate the waste management,
nutrient management, and production benefits of this
practice. Long term, it is hopeful that in-house
composting might be considered for cost-share
assistance as an NRCS waste treatment practice.
