Transcript Importance of Phosphorus •

Importance of Phosphorus
•
One of the most important minerals required by
livestock and poultry.
•
•
Complexes with calcium to give rigidity to bones.
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Almost every biochemical reaction that occurs in
muscle, blood and other soft tissues involves
phosphorus.
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Affects protein synthesis, lean deposition in growing
animals.
An integral part of many organic compounds – plays
important roles in energy and protein metabolism.
Phosphorus Requirements
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Best source of unbiased information on requirements is
the nutrient requirement publications of the National
Research Council (NRC).
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NRC is part of the National Academy of Sciences – a
private organization established 140 years ago by
President Abraham Lincoln to advise the nation on
issues of science and technology.
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The Committee on Animal Nutrition of the NRC has
established guidelines for feeding animals for past 75
years.
Nitrogen and Phosphorus in Animal
Manures
N
Manure from:
Swine
Poultry
Beef
Dairy
Sheep
Sweeten (1992).
P
(% of DM)
4.71
5.13
3.96
3.75
3.89
2.97
1.62
1.07
0.79
0.56
Swine and Poultry Manure High in
Phosphorus - Why?
• Diets (especially swine diets) generally tend to be
oversupplemented with phosphorus.
• Grains, oilseed meals in swine and poultry diets are
high in phytate phosphorus.
• Pigs and poultry are unable to degrade phytase and
utilize the phosphorus - no phytase in their
digestive tract.
• As a result, most of dietary phosphorus from the
natural ingredients is excreted in the feces.
Phytic Acid – The Culprit
O
P
O
O-
-
O
P
O
O
O-
-
O
Phytate Phosphorus
O
P
O
O-
-
O
P
O
O
O-
-
O
Phytate Phosphorus Content of Cereal
Grains, Byproducts, and Oilseed Meals
Phytate Phosphorus
% of total P
% of total
P
Barley
Oats
Corn
Wheat
Grain sorghum
Nelson et al. (1968).
56
56
66
67
68
Wheat bran
Wheat middlings
70
74
Soybean meal
Cottonseed meal
Sesame meal
61
70
81
Nutritional Strategies to Reduce
Phosphorus in Swine Manure
• Feed diets that are not excessive in phosphorus.
• Formulate diets on an “available phosphorus”
basis.
• Use feedstuffs that are low in phytate or that
have endogenous phytase.
•
Wheat, wheat byproducts, triticale, barley.
• Reduce dietary phosphorus and supplement with
phytase.
• Use low-phytate cereals and oilseed meals.
Model-Predicted P Excretion (kg) in GrowingFinishing Pig Fed Corn-Soy Diet from 20 to
120 kg
Kilograms of P
1.2
1.0
79% More P
Excreted
1.25
0.8
0.6
0.70
0.4
0.2
0.0
NRC (1998)
+ 0.2% Extra P
Phytase – What Does it Do?
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Increases phytate digestibility - increases
bioavailability of P in cereal grains and oilseed meals.
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Reduces the amount of supplemental inorganic P
needed to maximize growth and bone mineralization.
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Markedly reduces fecal P excretion.
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Increases the absorption of Ca, Mg, Zn, and other
divalent cations.
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May improve the utilization of dietary protein and
energy.
Low-Phytate Corn
Forms of Phosphorus in Germ of Normal
and Mutant lpa1 Corn
0.5
P in germ, %
0.4
Other Organic P
0.3
Inorganic P
0.2
Phytic Acid P
0.1
0
Normal
Raboy et al. (1990)
Mutant lpa1
Soluble Carbohydrates in Soybean
UDP
Sucrose
UDP-Glu
UDP-Gal
Myo-Inositol
ADP
1
Sucrose
2
Fructose
Glucose
+
Fructose
UDP
3
1
Glu6P
ATP
2
Myo-Inositol, 1P
Synthase
Galactinol Synthase
3
Raffinose Synthase
4
Stachyose Synthase
Galactinol
Myo-Inositol
Phytic
Acid
Raffinose
Galactinol
4
Myo-Inositol
Stachyose