Even though silkworms
didn’t work as well as planned last year, I still think there may be an
invertebrate we can easily raise to turn free plant matter into food
for our chickens.  One option might be snails, which have been
grown as human food for thousands of years.  Here’s an overview of
my current research into heliculture (raising snails).



What does a snail farm look like?

You can raise snails
indoors or outdoors, with various options available for both
arrangements.  Although it requires more work up front to make a
snail-proof (and predator-proof) pen, the lowest work in the long run is
to make a snail garden, in which case you only have to water and weed
the plants and harvest the snails — check out this booklet for more information. 
You can also make a much smaller outdoor snail pen (like the one shown
here) where you bring food to your snails.  Or you can build a
similar pen indoors.



What kind of snail should I raise?

If you’re raising snails
for chickens, you probably don’t care as much about gourmet
qualities.  In this case, your best bet in temperate regions is
probably Helix aspersa (the garden snail).  Helix aspersa is
a smallish snail with a weak shell, and individuals can reach full size
in one year if well fed (as opposed to three years in some other
species).  Like most
snails people raise for food, it is an herbivore, meaning the snail
needs to eat living plant matter.  As a result, you’ll want to be
very careful to prevent this snail from escaping from captivity since it
can become a major garden pest — this may be a reason to try out
different types of snails already found in your garden on your chickens
and choose one of those natives to raise instead.



What do snails eat?

Wikipedia lists the following food plants as being favored by snails:
“Alyssum, fruit and leaves of apple, apricot, artichoke (a favorite),
aster, barley, beans, bindweed, California boxwood, almost any cabbage
variety, chamomile, carnation, carrot, cauliflower, celeriac (root
celery), celery, ripe cherries, chive, citrus, clover, cress, cucumbers
(a favorite snail food), dandelion, elder, henbane, hibiscus, hollyhock,
kale, larkspur, leek, lettuce (liked, and makes good snails), lily,
magnolia, mountain ash, mulberry, chrysanthemum, nasturtium, nettle,
nightshade berries, oats, onion greens, pansy, parsley, peach, ripe
pears, peas, petunia, phlox, plum, potatoes (raw or cooked), pumpkins,
radish, rape, rose, sorrel, spinach, sweet pea, thistle, thorn apple,
tomatoes (well liked), turnip, wheat, yarrow, zinnia.”



In addition, the
FAO article linked to above recommends planting snail gardens
consisting of rape, horseradish, leaf beet (for shelter), burdock, and Plantago sp. (for shelter).  Snails can be introduced to their gardens when the plants are five to six weeks old.



Finally,
snails also need either plants or physical objects to shelter amid
during the day, well-drained loam soil in which to lay their eggs,
calcium (either from the soil or added as a supplement) to build their
shells, and plenty of moisture.



How much space do snails need?

In modern, high-density farms, Helix aspersa
can be kept in an area with one square foot for every six to eight
snails.  If you want the snails to breed, though, you’ll need to
give them more space — providing at least 1.25 square feet of room per
snail.  In snail gardens, snails are introduced at a rate of about
150 snails per 125 square feet, or 1.5 square feet per snail.



How much snail meat will I get?

If you raise a
fast-growing snail outdoors, a 125 square-foot pen will produce about 27
pounds of meat per year.  That’s about 9900 calories, nearly all
of which is from protein.  For the sake of comparison, you can get
about four times that many calories per acre from corn, but corn is only
about 8% protein and is much less healthy for your chickens.  As a
side benefit, snails are also very high in calcium and magnesium.