Importance of Phosphorus One of the most important

Importance of Phosphorus • One of the most important minerals required by livestock and poultry. • • Complexes with calcium to give rigidity to bones. • Almost every biochemical reaction that occurs in muscle, blood and other soft tissues involves phosphorus. • 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 • 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 Manure from: Swine 4. 71 Poultry 5. 13 Beef 3. 96 Dairy 3. 75 Sheep 3. 89 Sweeten (1992). 2. 97 1. 62 1. 07 0. 79 0. 56 P (% of DM)

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

Phytate Phosphorus Ca++ O - O ++ Zn O P O- O O M g ++ P O O O - P O - O O- - O O O- Fe++ O P - O Zn O P O O O - - O ++ ++ - O Cu P O -

Phytate Phosphorus Content of Cereal Grains, Byproducts, and Oilseed Meals Phytate Phosphorus % of total P P Barley 56 Wheat bran 70 Oats 56 Wheat middlings 74 Corn 66 Wheat 67 Soybean meal 61 Grain sorghum 68 Cottonseed meal 70 Sesame meal 81 Nelson et al. (1968). % of total

Nutritional Strategies to Reduce Phosphorus in Swine Manure • • Feed diets that are not excessive in phosphorus. • Use feedstuffs that are low in phytate or that have endogenous phytase. Formulate diets on an “available phosphorus” basis. • 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 lpa 1 Corn Other Organic P Inorganic P Phytic Acid P Raboy et al. (1990)

Soluble Carbohydrates in Soybean UDP Sucrose UDP-Glu UDP-Gal 2 Fructose ADP Glucose + Fructose 1 UDP 1 Myo-Inositol Glu 6 P ATP 2 Myo-Inositol, 1 P Synthase Galactinol Synthase 3 Raffinose Synthase 4 Stachyose Synthase Sucrose Galactinol 3 Myo-Inositol Phytic Acid Raffinose Galactinol 4 Myo-Inositol Stachyose