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return to Farmers
Independent Weekly
February
27, 2003
By Martin Nyachoti, Department of Animal
Science |
Phosphorus
in pork production: strategies for optimizing its utilization
Phosphorus
is in essential nutrient required by pigs for various important
physiological functions and must, therefore, be supplied in
the diet. Various ingredients including cereal grains, protein
supplements and inorganic sources such as dicalcium phosphate
are used to supply phosphorus in pig feeds. The amount of
phosphorus that is actually available to pigs from these sources
varies widely and creates major challenges in accurate feed
formulation. Any phosphorus consumed and not retained by the
pig is eventually excreted in manure thus potentially contributing
to environmental pollution. This article briefly discusses
strategies for optimizing dietary phosphorus utilization in
pork production.
Dietary
phosphorus should be carefully managed in livestock feed.
Phosphorus is the third most expensive nutrient in swine feed
after energy and protein. Therefore, effective management
of its supply and utilization presents significant cost saving
opportunities for the swine industry. As well, phosphorus
easily accumulates in the soil and large amounts entering
water bodies through leaching or surface runoff can lead to
algal blooms and endanger aquatic life forms. This means that
high levels of phosphorus in manure will influence the amount
of manure that can be safely applied to cropland.
Many different
strategies for managing dietary phosphorus are now available
to the swine industry, although their usefulness under different
production situations remains to be fully characterized. The
following are some of the approaches that could be used to
increase dietary phosphorus utilization and therefore minimize
its excretion in pig manure:
- Matching
dietary phosphorus supply with the pig’s requirements.
Because any phosphorus not used by the pig is excreted,
it is important to formulate swine feeds closely matching
dietary phosphorus supply with requirements. It is known
that the efficiency of phosphorus utilization in different
pig farms vary widely and that this is partly due to differences
in the genetics of the pigs. Establishing the phosphorus
requirements of different pig genotypes is useful in matching
supply with requirements thus enhancing production efficiency
and minimizing excretion in manure.
- Characterizing
phosphorus availability in pig feed ingredients.
About 70% of phosphorus in cereals exists as phytate phosphorus
which is not easily digested by swine. Consequently, pig
feeds should be formulated on the basis of available phosphorus
content. However, the available phosphorus in many pig feed
ingredients including alternative feedstuffs important to
western Canada (e.g., peas, canola meal, hulless barley,
etc.) is either unknown or not well characterized. Knowing
the available phosphorus content in alternative and commonly
used feed ingredients is an important step toward effective
dietary phosphorus management in pork production. Current
research at the University of Manitoba is geared at addressing
this issue.
- Ingredient
selection and processing. Utilizing ingredients
with high phosphorus digestibility/availability (e.g., corn
or hulless barley with high available phosphorus) can contribute
to effective phosphorus management. For example, when pigs
are fed diets that reduce manure volume, such as hulless
barley, the total phosphorus excretion is also reduced.
Similarly, our recent research suggests that ingredient
processing procedures such as micronization that improves
nutrient digestion in pigs can lead to significant reductions
in manure phosphorus content. However, additional research
is necessary to fully develop this strategy.
- Use
of commercial feed enzymes and other additives.
Adding phytase, the enzyme required to digest phytate-bound
phosphorus in pig feed ingredients, is now a common practice
in parts of the world where the contribution of animal agriculture
to environmental pollution is a major concern. Recent research
suggests that using commercial phytase might eliminate the
need for sources of inorganic phosphorus, such as dicalcium
phosphate, in swine rations. This will potentially reduce
feed cost while minimizing the amount of phosphorus excreted
in pig manure. Ongoing research at the University of Manitoba
has shown that the addition of microbial phytase plus organic
acids improves phosphorus utilization in young pigs thereby
reducing the amount of phosphorus in the non-digested material
that is subsequently excreted. A reduction in phosphorus
excretion of up to 20% has been achieved as a result of
microbial phytase plus organic acid supplementation. It
is important to note that there are still many unanswered
questions that must be addressed to optimize this strategy
in dietary phosphorus management. Our research in this area
should provide answers to some of these questions.
Efforts
to better understand how to increase phosphorus utilization
in pork production will not only increase efficiency of production,
through reduced feed cost, but will also benefit industry
efforts to implement environmentally sustainable production
practices. Continued research in the identified areas to customize
their usefulness to local production conditions will certainly
go a long way toward optimizing dietary phosphorus utilization
in pork production.
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