Reducing pigs’ phosphorus emissions may have more than an environmental benefit – it may also save farmers money by cutting their feeding costs.
Phytase, a microbial feed additive that reduces phosphorus excretions, appears to help young animals make better use of a variety of minerals and compounds already present in the feed, but which hog producers usually buy and add to their feeds.
Because phytase causes more phosphorus in grain-based hog feed to become available to a pig’s digestive tract, less of it is excreted in the feces.
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Lee Southern, a researcher at the Louisiana State University’s Agricultural Research Centre, has found that by adding phytase to feed, trace mineral feed supplements can be eliminated without the skin lesions, poor daily gain and eventual death that would occur without the compounds.
In addition to extracting more minerals such as copper, iron, zinc and manganese from the feed, phytase also appeared to increase the uptake of calcium, fats, amino acids and phosphorus.
“We were really quite surprised how much more efficient phytase made the feed,” Southern said.
Casey Smit, feeds manager with Big Sky Pork in Humboldt, Sask., said his company feeds phytase to reduce phosphorus emissions.
“It is a part of our vitamin pack. But if there were solid research to show that phytase did allow us to reduce other additives, we would have to look at that. There aren’t a lot of things that come along that allow producers to reduce costs … but it would have to be some pretty good research to get us to change.”
Many producers say the 80 cents to $1.20 they spend on trace minerals per tonne of feed isn’t enough to cause them to rush into changing their practices, but add that any savings would be welcome.
John Patience, head of the Prairie Swine Centre in Saskatoon, said the research is little known in Canada and the United States.
“A lot more work would need to be done, but it does make some sense that the phytase is improving the use of other trace minerals as well as phosphorus.”
The Louisiana study looked at 208 crossbred barrows and gilts that were weaned at 21 days. They were divided into four groups and fed diets based on corn and soybean meal.
A control group was fed a conventional nursery diet that included a trace mineral pack. A second group was fed a control diet without the trace minerals, a third received a control diet with phytase and the standard mineral pack, and a fourth received a control diet with phytase and no mineral pack.
“We found that without the mineral premix and without phytase that half of the animals showed skin lesions and gained 20 percent less than the other three groups, which were pretty even, and that the best gain was in the group that had the phytase, but didn’t have the mineral premix,” Southern said.
The 34-day post-weaning study showed gains of 607 grams per kilogram of feed for the control diet with phytase and without the mineral supplement, compared to 587 g of gain per kg of feed for the control feed plus phytase, and 584 g per kg for the control group.
The group that wasn’t fed minerals fared the worst with an average daily gain of 277 g per day, while the group with the phytase and without the minerals did the best at 350 g per day.
The control group achieved 342 g per day in gain while adding phytase dropped the average daily gain to 338 g.
At the beginning of the study, the gilts’ average body weight was 5.4 kg and the barrows were 5.6 kg. At the end of 34 days, the gilts weighed 15.9 kg and the barrows 16.4.
Southern said adding phytase to the diet meant the mineral supplement could be eliminated without “any noticeable loss in production or herd health.”
While his research project has ended, he hopes other scientists and producer groups will build on his team’s findings.
“I think there is more that we still don’t know about the effect of phytase on the diet. And if we are extracting additional copper and zinc from the feed, then it doesn’t end up in the feces. In some countries in Europe, they are not even allowing these minerals to be added to the finisher pig diets. I think there is room for a lot more research by somebody in this area.
“It is good to say you may have found something that saves producers’ money, but this was a small test and it needs to be replicated a number of times to ensure it will work.”
