Phytic acid in chicken feed
I'm thinking about feeding
our chickens more homegrown seeds this year, so I decided I'd better
look into the one safety issue --- phytic acid (aka phytates).
sums up the issue in a nutshell:
is present in beans, seeds, nuts, grains—especially in the bran or
outer hull; phytates
are also found in tubers, and trace amounts occur in certain fruits and
vegetables like berries and green beans. Up to 80 percent of the
phosphorus—a vital mineral for bones and health—present in grains is
locked into an unusable form as phytate. When a diet including more than
small amounts of phytate is consumed, the body will bind
calcium to phytic
acid and form insoluble phytate
complexes. The net result is you lose calcium, and don’t absorb
phosphorus. Further, research suggests that we will absorb
approximately 20 percent more zinc and 60 percent magnesium from our
food when phytate
So, feeding your
chickens (or yourselves) lots of raw beans, seeds, nuts, and grains can
make them malnourished since they won't be able to get the phosphorus,
calcium, zinc, and magnesium they need. Luckily, there are
several possible solutions.
Does that sound
complicated enough to send you scurrying away from trying to make your
own chicken feed? I hope not --- after all, I suspect the big
feed companies don't pay that much attention to phytic acid when they
mix their feeds. Some scientists suggest that the high phosphorus
levels in chicken manure are the direct result of feeding chickens food
high in phytic acid which they can't digest. Surely we can do
the seeds. Especially with legumes, soaking the seeds at
warm temperatures (140 degrees Fahrenheit is most effective) for up to
36 hours can reduce the phytic acid content enough to double the
nutrition you get from the seeds. Just soaking for 18 hours at
room temperature removed half to two thirds of the phytic acid from
three kinds of beans. This is much more effective than sprouting
the seeds or cooking them. See this
blog for more information.
- Remove the seed coat.
the phytic acid is found in the seed coat, so white flours and similar
products are much safer in this respect. Unfortunately, most of
nutrition in seeds is also found in the seed coat, so you should use
this technique with caution.
- Grind seeds and soak the mash.
Traditionally, farmers used to grind grains and legumes into a mash
which they soaked before feeding it to pigs and chickens.
(Ruminants don't have as much trouble with phytic acid, so this wasn't
necessary when feeding cows, etc.) This technique activates a
protein called phytase, which is already found in the seeds (especially
in rye) and which breaks down the troublesome phytic acid. This
is also part of the theory behind making sourdough bread.
- Choose seeds lower in phytic acid.
the best sources of protein also seem to be the worst phytic acid
offenders. Soybeans, peanuts, almonds, and sunflower seeds have
three times as much phytic acid as cowpeas (which seem to be one of the
safer seeds.) Grains tend to fall somewhere in the middle.
- Grow our own seeds.
acid content within the same type of seed varies drastically depending
on how the seeds were grown. Some studies suggest that raising
seeds with compost instead of chemical fertilizer (especially high
phosphate fertilizer) will reduce the phytic acid content.
Fresher seeds will also help since these seeds have more phytase to
counteract the phytic acid.
- Increase vitamin C in the diet.
Ascorbic acid in the diet has been shown to counteract the effects of
phytic acid, at least with regard to iron absorption. So, if you
your chickens a lot of fresh fruits and vegetables at all times rather
than making seeds the entirety of their diets, the phytic acid won't be
as much of a problem. In general, the more well-rounded your
chickens' diet is, the less difference a bit of phytic acid will make
in their lives.
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