Feed Inputs to Animals

Bob von Bernuth

Considerations in a Ration/Diet

EnergyProteins & Amino AcidsMineralsVitaminsNon-nutritative additives

Energy

Energy is produced when organic molecules undergo oxidation.

C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + energy

Proteins and Amino Acids

Proteins are amino acidsThere are limiting amino acids Lysine Methionine A lot of others! They should be balanced

Amino acids are the main source of N Limiting amino acids results in reducing N

excretion.

MineralsAnimals generally have a dietary requirement for

Calcium Chlorine Copper Iodine Iron Magnesium Manganese

PhosphorusPotassiumSeleniumSodiumSulfurZinc

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.

Swine versus Dairy

Swine are a monogastricDairy cattle are ruminants Ruminants have a rumen (large

stomach) Rumen contains bacteria which

produce phytase enzyme—breaks down phytate feedstuffs

Nonruminants don’t

Swine Considerations

Since they don’t have phytase—we have to overfeed P in order to ensure adequate available P. Or—we can add phytase—it works in swine, it just isn’t produced there (it also works for poultry)Or—we can use low phytate corn

Phosphorus

Essential for skeletal system developmentGenerally low availability Feedstuffs—60-75% is phytate (not

available) Corn grain—14% Soybean meal—23-30%

What happens to the rest?

Nitrogen and Phosphorus in Animal Manures

N P

(% of DM)

Manure from: Swine 4.71 2.97 Poultry 5.13 1.62 Beef 3.96 1.07 Dairy 3.75 0.79 Sheep 3.89 0.56

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

PO

-

- O

O

O

PO -

-OO

OP

O-

- O

O O

PO

--O

OO

PO-

-O

O

OP

O-

-OO

O

Phytate Phosphorus

PO

-

- O

O

O

PO -

-OO

OP

O-

- O

O O

PO

--O

OO

PO-

-O

O

OP

O-

-OO

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 Barley 56 Wheat bran 70Oats 56 Wheat middlings 74Corn 66Wheat 67 Soybean meal 61Grain sorghum 68 Cottonseed meal 70

Sesame meal 81

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

0.70

1.25

0.0

0.2

0.4

0.6

0.8

1.0

1.2

NRC (1998) + 0.2% Extra P

Kilo

gram

s of

P

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

0

0.1

0.2

0.3

0.4

0.5

Normal Mutant lpa1

P in

ger

m, %

Raboy et al. (1990)

Phytic Acid P

Inorganic P

Other Organic P

Soluble Carbohydrates in Soybean

SucroseUDP

UDP-Glu

Glucose+

Fructose

Fructose

UDP

Galactinol

Myo-Inositol

Sucrose

Raffinose

1

1 Myo-Inositol, 1P Synthase

ATP

ADP

Glu6P

2

Galactinol Synthase2

3

Raffinose Synthase3

4

Stachyose Synthase4

UDP-Gal

Myo-Inositol

PhyticAcid

PhyticAcid Galactinol

Myo-Inositol

Stachyose

Dairy Considerations

A dairy cow has phytase. Perhaps because of the large amount of feed she eats (50-60 lb/day) some phytase might help.However, we tend to overfeed P.

Why Do We Overfeed P?

Safety margin Not neededIncreased milk yield Doesn’t workHypophasphatemia Doesn’t helpImproves reproduction Data ???P in feed unknown No excuse

You Get Back What You Put In!

P has no gaseous phase It can’t escape to the air If you fed it, it’s in the animal, the

milk or the excretion. If you manure sample doesn’t show it,

you better look for it.

Dairy Phosphorus Balance

Total Intake

90

Unavailable

9Potentially Available

81

Milk

29

Truly Absorbed

63

189

34

34 = 61+ +

Nutrients retained by animals(Elemental)

Animal N P K

Beef 0.016 0.007 0.002

Dairy 0.012 0.007 0.002

Pork 0.023 0.007 0.002

Layers 0.022 0.006 0.002

Broilers 0.026 0.006 0.002

Turkeys 0.021 0.006 0.002