Phosphorus
in Swine
Diets
Shanna Robinson
Swine Formulator
Phosphorous in Swine Diets
Introduction
Phosphorus is a key nutrient for optimizing pig growth and supporting sow performance
and longevity. However, phosphorus is an increasingly expensive nutrient to add to swine
diets. With alternative uses in fertilizers, some shortages of inorganic phosphorus have
been seen. Therefore, it is prudent to examine how phosphorus is used in swine diets and
what is used to meet the requirements for phosphorus in these diets.
Phosphorus in Feed Ingredients
Phosphorous in plant feedstuffs is found in 2 forms either as phytate (organically bound
phosphorous) or as non-phytate phosphorous.
In most plant materials, a large proportion of phosphorous in plant material is phytate
phosphorous which is the chief storage form of phosphorous.
For cereal and plant proteins, the percentage of phosphorous as phytate varies from 60 to
80% of the total phosphorous. By-products generally have a higher phosphorous and
phytate content than the parent grain. For example, hard red winter wheat contains 0.37%
phosphorous; wheat shorts contain 0.84% phosphorus, but a lower percentage of the
phosphorus is available.
Pigs do not have the phytase enzyme naturally in their digestive system and therefore
have a limited ability to digest phytate phosphorous in the diet. Therefore, the availability
of plant phosphorous to pigs is low.
In animal derived feed ingredients, phosphorus is generally at higher levels and has a
greater percent of the phosphorus available to the animal. For example, the availability of
phosphorus in meat-and-bone meal is 80 % or higher.
Based on literature review and internal research, Shur-Gain has determined the
available phosphorus content of all common feed ingredients.
Determination of the Pigs Phosphorus requirements
The phosphorus requirement of the growing pig is determined by its need for skeletal
development and for muscle growth. The amount of phosphorus required by the pig is
dependent on the pig’s stage of growth. These requirements can be estimated through the
use of the Watson® swine model as it simulates growth of the pig through its life cycle.
In developing gilts, additional phosphorous is required to increase bone mineralization
and to condition the developing gilt for a long and productive life span.
During gestation, the requirement for phosphorus is in direct proportion to the need for
growth and development of the developing piglets, while in lactation, the requirements for
phosphorus are determined by the level of milk production by the sow.
Shur-Gain formulates all swine diets to meet the pig’s requirements for available
phosphorous versus total phosphorus. As examples, all our MAXUM sow rations and
supplements are formulated carefully on an “Available phosphorus” basis. Similarly, our
IMPACT 4e, EXCEL, PRECISION and DYNAMIZE complete line of starter/grower feeds
are all carefully formulated on an “Available phosphorus” basis.
Optimizing phosphorus for pigs
Given that the cost of adding phosphorus as dicalcium phosphate is increasing, it is
critical that we optimize the utilization of phosphorus in the diet and meet the animals’
requirements more closely. There are several steps that can be done.
1. Determining the pig’s requirements for phosphorous at any given stage of its
life cycle enables nutritionists to better formulate diets that meet requirements
while at the same time eliminating wastage through the manure. This can be
done by using Watson® to model the pig’s requirements for available
phosphorus.
2. Formulating the diet on an “Available-Phosphorous” basis. This is a more
precise way of formulation and better addresses the pig’s need for phosphorus.
3. Accurate chemical analysis of the phosphorus content of feed ingredients and
updating the ingredient nutrient database.
4. Use of supplemental phytase in the diet to breakdown the phytate phosphorus
into a form the pig can use, reducing the need for supplemental phosphorus
from dicalcium phosphate. This effectively lowers the “Total” phosphorus in the
diet and reduces the amount of phosphorus excreted in the diet.
5. Increasing the availability of phosphorus from ingredients lowers the net feed
cost despite having to add the phytase to the diets. This, therefore, lowers the
cost to raise pigs to market.
6. Use of proteins from animal sources e.g. meat-and-bone meal. Generally
phosphorus from ingredients that are of animal origin has higher availability to
pigs, compared to phosphorus from plant origin.
In formulating diets for swine, SHUR-GAIN takes into consideration all of the above,
and formulates on an “Available-phosphorous” basis. This ensures an effective use of
phosphorous in the pigs’ diet maintaining performance and lowering feed costs.