Importance of Phosphorus One of the most important minerals required by livestock and poultry. Complexes with calcium to give rigidity to bones. An integral part of many organic compounds – plays important roles in energy and protein metabolism. Almost every biochemical reaction that occurs in muscle, blood and other soft tissues involves phosphorus. Affects protein synthesis, lean deposition in growing animals.

Phosphorus Requirements Best source of unbiased information on requirements is the nutrient requirement publications of the National Research Council (NRC). 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. 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 P (% of DM) Manure from: Swine Poultry Beef Dairy Sheep Sweeten (1992).

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 P O-O- -O-O O O P O-O- -O-O O O P O-O- -O-O O O P O-O- -O-O O O P O-O- -O-O O O P O-O- -O-O O O

Phytate Phosphorus P O-O- -O-O O O P O-O- -O-O O O P O-O- -O-O O O P O-O- -O-O OO P O-O- -O-O O O P O-O- -O-O O O Zn ++ Ca ++ Cu ++ Zn ++ Mg ++ Fe ++

Phytate Phosphorus Content of Cereal Grains, Byproducts, and Oilseed Meals Phytate Phosphorus % of total P % of total P Barley56Wheat bran70 Oats56Wheat middlings74 Corn66 Wheat67Soybean meal61 Grain sorghum68Cottonseed meal70 Sesame meal81 Nelson et al. (1968).

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 Growing- Finishing Pig Fed Corn-Soy Diet from 20 to 120 kg 79% More P Excreted

Phytase – What Does it Do? Increases phytate digestibility - increases bioavailability of P in cereal grains and oilseed meals. Reduces the amount of supplemental inorganic P needed to maximize growth and bone mineralization. Markedly reduces fecal P excretion. Increases the absorption of Ca, Mg, Zn, and other divalent cations. May improve the utilization of dietary protein and energy.

Low-Phytate Corn

Forms of Phosphorus in Germ of Normal and Mutant lpa1 Corn Raboy et al. (1990) Phytic Acid P Inorganic P Other Organic P

Soluble Carbohydrates in Soybean Sucrose UDP UDP-Glu Glucose + Fructose UDP Galactinol Myo-Inositol Sucrose Raffinose 1 1 Myo-Inositol, 1P Synthase ATP ADP Glu6P 2 Galactinol Synthase 2 3 Raffinose Synthase 3 4 Stachyose Synthase 4 UDP-Gal Myo-Inositol Phytic Acid Phytic Acid Galactinol Myo-Inositol Stachyose