Loren Muldowney's story about "limberneck" resulting from feeding
chickens on maggots is one I'd heard from a local knowledge
perspective out east, as well. My dad worked on some friends' pig
farms in Essington, PA, before and after his service in World War
Two. Most of those farms were diversified and also had poultry, and I
can remember him talking about this. He was a compassionate man, and
couldn't stand to see animals suffering.
Loren--good question you raised--because you've challenged my
thinking that these maggots could be biocontrolled by birds in an
urban composter. See below.
"Limberneck" is a condition caused by avian botulism. I posted here
recently about ponds as reservoirs of avian botulism.
--U.S. Fish and Wildlife service info:
http://www.emtc.nbs.gov/http_data/nwhc/factshts/avian.html
The authors are at the National Wildlife Health Laboratory, in Madison.
"Avian Botulism affects the nervous system, causing muscle paralysis.
Depending on how far the disease has progressed, various levels of
paralysis will be
observed. An early sign in birds is the inability to fly. Once the
ability to fly is lost and leg muscles become paralyzed, ducks
suffering from botulism often propel
themselves across the water and mud flats with their wings. This
sequence of signs is in contrast to that of lead-poisoned birds,
which have difficulty flying but
remain able to walk and run.
"Paralysis of the inner eyelid and neck muscles follows. These are
the two most easily recognizable signs associated with avian
botulism. The inability of the bird to hold its head erect is the
reason this disease is called "limberneck." Frequently, birds will
drown once they reach this stage in the disease. Those that do not
drown will eventually die from respiratory failure as paralysis
spreads.
"Favorable environmental conditions occur in the tissues of decaying
animal and insect carcasses. The decomposition process uses up all
available oxygen in the
carcass, creating anaerobic conditions. Bacterial spores ingested
during the life of the animal germinate after death. As the bacteria
multiply and die, the toxin is
released.
"The cycle of avian botulism
"Outbreaks of avian botulism occur when the toxin is taken in by
birds. The die-off may begin as birds feed directly on invertebrate
carcasses that contain the toxin, or as a result of feeding on live
maggots of flesh-flies and blowflies. Flies lay their eggs on dead
vertebrates, and the resulting maggots store botulinal toxin in their
bodies as they consume the carcass. More than 5,000 maggots can be
produced by a single bird carcass; consumption of just two to five
toxin-bearing maggots is
often enough to kill a duck!"
Note that the difference between this and Kate's situation is that
the source of the botulinal toxin is dead vertebrates and
invertebrates. Kate is decomposing/composting vegetables. Which is
what I was thinking when I suggested laying the heap open to the air
for city birds to pick at.
However, from
--Texas A&M
http://gallus.tamu.edu/Diseases/PDSec5.htm#BOTULISM
comes this:
"Botulism is a disease caused by the ingestion of a toxin produced by
the anerobic bacterium Clostridium botulinum. All domestic fowl and
most wild birds are susceptible. An interesting exception is the
vulture, which is apparently immune and feeds on decaying carcasses.
Many human deaths have been attributed to their consuming food or
water containing the toxin.
"Cause: Botulism is not a bacterial infection, but a condition
produced by ingestion of a toxin produced by the bacterium Cl.
botulinum. The organism is
common in nature and is widely dispersed in soils. Ingestion of the
organism is not harmful. It becomes dangerous only when conditions
are favorable for the
growth and multiplication of the bacteria and its subsequent toxin
production. The organism grows best under high humidity and
relatively high temperature and
in an environment containing decaying organic material. Acid
conditions are detrimental. Stagnant pools or damp areas containing
decaying matter with an
alkaline reaction are a danger area. Botulism may result from
consumption of any decaying animal or vegetable. Decaying carcasses
are a frequent source of
toxin, and fly maggots feeding on such tissue may contain enough
toxin to cause the disease when ingested. The toxin is water soluble;
consequently, water
sources may become contaminated.
"The toxin is one of the most potent, being about 17 times as deadly
as cobra venom for the guinea pig. The toxin is relatively heat
stable but may be destroyed by boiling. There are different types of
the toxin. Types A and C usually are responsible for the disease in
birds, while type B most frequently affects man."
So this indicates that maggots in partly-finished compost *could* be
a problem for birds, under certain circumstances?
There is some good informationon avian botulism/limberneck at:
--Environment Canada
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/ab_1.html
See especially,
--"Methods of tranfer" for info on maggots:
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/ab_4.html
That site also has an EXTENSIVE annotated bibliography on avian botulism
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/ab_7.html
See especially:
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab24.html
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab2.html
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab175.html
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab65.html
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab262.html
This one intrigued me: it lists a bunch of antibiotics that people
can feed chickens to control botulism; this refers back to the
ongoing SANET discussion of antibiotics in the food chain, and the
notion of drugging animals to overcome pathogens caused by systemic
imbalances:
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab292.html
One last resource:
--Skipio's (breeder of insects for kept birds and reptiles)
http://www.skipio.com/birds.htm
"Insects are a natural nutrition source for all birds at some point
in their development except for some who obtain their animal protein
from fish, mammals, reptiles or amphibians. Live mealworms and
crickets, originally marketed as fish bait, have long been available
for feeding birds and other animals. These insects were grown on
vegetable diets. Some bird breeders to their dismay tried feeding
their birds maggots that were grown on offal or wastes from the local
butcher shop. The maggots were suitable for fish bait but could carry
claustridium botulinum that resulted in fatal limberneck disease. A
mistaken idea associated with those larvae was that they could be
cleansed with corn meal. That was not true. Only insects that have
been grown on vegetable diets should be fed to birds!"
Sooooo. Not sure where that leaves us. My guess would be that if the
conditions in the heap weren't too alkaline, and what went into it
was clean (not rotted) food, the chance of botulin toxin accumulating
in the maggots would be relatively low.
Comment, anyone?
Hope this is of use to you-all with poultry, as well. I've seen
chickens go after maggoty produce, either gleaning in the garden, or
something left too long in the scrap bucket (which is also risking
Salmonellosis).
Finally, Loren, you asked about feeding maggots to fish.
Here's a nice little site that looks like a student one, very well referenced:
http://iaith.simplenet.com/botulism/botubird.html
The student was apparently in a course on Microbial Disease and Human
Society. The above URL has an item about botulism in fish, and
footnotes.
Also:
http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab50.html
Now that we've had this discussion, watch for Dennis Avery to show up
claiming that composting causes botulism.
:^)
(not sure why I'm smiling)
peace
misha
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Michele Gale-Sinex
Communications manager
Center for Integrated Ag Systems, UW-Madison
http://www.wisc.edu
UW voice mail: 608-262-8018
Home office: 415-504-6474 (504-MISH)
Home office fax: Same as above, phone first for enabling
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