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Saturday, July 28, 2012
Helping Pigs to Digest Phosphorus
This is a nice bit of work that will even be economically viable. I
also wonder were else this type of thinking may apply. Obviously it
will allow a more efficient use of certain feeds and this is good.
Phosphorus is a vital
nutrient for pig growth, but pigs do not always digest it well.
Research conducted at the University of Illinois has determined how
adding various levels of the enzyme phytase to the diet improves how
pigs digest the phosphorus in four different feed ingredients.
Improving phosphorus digestibility has positive implications for
producers' bottom lines as well as for the environment.
"The majority of
the phosphorus in plant feed ingredients is bound in phytate,"
said U of I animal sciences professor Hans Stein. "It is
difficult for pigs to utilize that phosphorus because they cannot
hydrolyze that phytate molecule. There is an exogenous enzyme called
phytase that helps the pigs hydrolyze that phosphorus bond from
phytate so the digestibility is increased."
However, there are no
data on the response to different levels of phytase in the diet.
"It's not known if we need to add 500, or 1,000, or 1,500 units
of phytase to get a maximum response, and it's also not known if the
response is the same when we use different feed ingredients,"
Stein's team tested
the digestibility of phosphorus in conventional corn grain, corn
germ, distillers dried grains with solubles (DDGS), and high-protein
distillers dried grains (DDG). They tested each ingredient with no
phytate and with 500 units, 1,000 units, and 1,500 units of added
500, 1,000, and 1,500 units of phytate increased phosphorus
digestibility from 40.9 percent in corn grain with no added phytate
to 67.5, 64.5, and 74.9 percent, respectively. Phosphorus
digestibility in corn germ increased from 40.7 percent to 59.0, 64.4,
and 63.2 percent, respectively. Digestibility of phosphorus in DDGS
increased from 76.9 percent to 82.9, 82.5, and 83.0 percent,
respectively, but the increase was not significant. Phosphorus
digestibility in high protein DDG increased from 77.1 percent to
88.0, 84.1, and 86.9 percent, respectively.
discovered was that for corn and corn germ, we had a low
digestibility without phytase, but as we added phytase to the diet,
we increased the digestibility quite dramatically," Stein said.
For DDGS and
high-protein DDG, the result was quite different. Because these two
ingredients have been fermented, some of those phytate bonds are
hydrolyzed in the
ethanol plant and
therefore, less of the phosphorus is bound to phytate in DDGS and
"When we added
phytase to DDGS, we did not see a significant increase in
digestibility because the digestibility was already very high. And
the same was true for HP DDG," said Stein. "What this tells
us is that the effect of phytase depends on the particular
ingredient. If it's an ingredient that has a lot of phosphorus bound
to phytate, we see a nice response, but if it doesn't have much
phosphorus bound to phytate, we don't see nearly as much of a
The second finding was
that the response to phytase is not linear. "The response to the
initial 500 units of phytase is much greater than if we add another
500 units or another 500 units after that," said Stein. "It's
a curvilinear response, even for the ingredients where a good
response is obtained."
developed equations to predict the response to every level of phytase
supplementation up to 1,500 units.
This research will
help producers and feed companies to increase the digestibility of
phosphorus in ingredients they are already feeding, thus avoiding the
expense of adding dicalcium phosphate or monocalcium phosphate to
prices, it's less expensive to use phytase than it is to use
dicalcium phosphate or monocalcium phosphate," Stein pointed
out. Use of phytase to improve phosphorus digestibility also reduces
the amount of phosphorus excreted in feces, which in turn reduces the
environmental impact of swine production.
Stein's lab is
continuing its research into phytase supplementation and is currently
testing different sources of canola meal and soybean meal. He and his
team plan to conduct similar research for all major feed ingredients
used in U.S. swine diets.
The study was
published in a recent issue of the Journal of Animal Science and was
co-authored with doctoral candidate Ferdinando Almeida.