Ruminant Animal Feed Management Issues and

Practices

CNMP Core Curriculum

Feed Management – Section 6.2

CNMP Development Core Training Curriculum

These course materials have been developed as a cooperative effort between five land-grant universities and The Natural Resources Conservation Service.

Ames, Iowa 50011, (515) 294-4111.

Copyright © 1995-2006, Iowa State University of Science and Technology. All rights reserved.

Copyright Information

Objectives

• Diet composition for ruminants

• Review digestion processes and excretion of N and P of the ruminant

• Discuss aspects of ration balancing

• Discuss reasons for overfeeding of nutrients

• Provide strategies for reducing nutrient excretion

Supplemental Materials

• NRC Nutrient Requirements of Dairy Cattle

• NRCS Nutrient Management Technical Note 5

• LPES Lesson No. 12 Feeding Dairy Cows to Reduce Nutrient Excretion NRC Nutrient Requirements of Beef Cattle

• NRCS Nutrient Management Technical Note 2

• LPES Lesson No. 13 Using Dietary Strategies to Reduce the Nutrient Excretion of Feedlot Cattle

Ruminant Nutrition

You are NOT just feeding the steer or cow! You are also feeding the microorganisms in the rumen.

You must feed and meet the needs of the ruminal microorganisms and the animal.

Dairy DietsDigestibility (availability of nutrients) of forages:• Amount of forage• Type of forage• Maturity of forage

Higher digestibilities increase utilization and

decrease nutrient excretion. Lower digestibilities

decrease utilization and increase nutrient excretion.

Dairy DietsConcentrates 45-60

Grains (corn, milo, barley, etc)Protein meals (soybean meal, Soypass,

Cottonseed, distillers grains, etc.)Byproducts (corn gluten feed, beet pulp,

soyhulls, etc.)

Forages 40-55alfalfa hay, corn silage, haylage, grasses

grazing? Supplement 2-10

dry-pellet, dry-meals, liquidminerals, protein?, vitamins, additives

0

50

100

150

200

250

300

350

400

14-Apr 24-Apr 4-May 14-May 24-May 3-J un 13-J un

Date

CelluloseCPLignin

Relationship between advancing maturity of first cut orchard grass and chemical

composition.

TSP Question to Producer

• How do you manage your forages?

• Buy or home grown?

• Are you maximizing the amount of home grown forages in the ration?

Feedlot Diets

Corn/Milo 50-85High-moistureDry-rolledSteam-flakedWhole

Roughage (alfalfa hay, corn silage) 0-10Byproducts (distillers/gluten feed) 15-40Molasses/Liquid 0-5Supplement 3-8

dry-pelletliquid

A Few Terms and Definitions

• Crude protein (CP) = N x 6.25

• Some protein is used by microorganisms in rumen and some are absorbed in small intestine

• Rumen degradable protein (RDP) = CP that is degraded in the rumen; required by bacteria to grow (DIP in beef)

• Rumen undegradable protein (RUP) = “escape or bypass” CP that is NOT degraded in rumen but passes to lower tract (UIP in beef)

Digestive Process of Ruminants

Rumen

MCPAA

Ammonia

RDPNPN

Degraded by microorganisms

MCPAARUPUrea

Fecal N

Sm Intestine

BUN

Milk Urea NMilk and

Meat

Diet CP

Ruminant Nutrition

• Goals– Provide adequate amount of rumen

degradable protein:• For optimal rumen health• For optimal rumen efficiency

– Provide adequate amount of rumen undegradable protein:

• To obtain the desired animal productivity

Protein

Ruminant Nutrition

• Excess N excretion typically due to imbalance of RDP and RUP and too much of one, or both– Excess RDP increases ammonia production

in rumen which leads to:• Decrease reproductive performance (toxic effect)• Decrease lactation performance (energy cost)• Increases urinary N excretion

– Excess RUP:• Not utilized by animal • Increases fecal and urine N excretion

Protein

Intake

Retention

Excretion

Intake-Retention=Excretion

Excretion in feces & urine

Ruminant Nutrition

• Estimate N excretion (dairy):– Milk production– Days in milk– Dry matter intake – Body weight – Milk protein content– Concentration of CP in ration

Protein

Ruminant Nutrition

• Estimate N excretion (beef):– Dry matter intake– Concentration of CP in ration– Days on feed for individual ration– Purchase weight (initial weight)– Market weight (ending weight)– Standard reference weight for expected final

body fat

Protein

Overfeeding protein increases N losses!Nutrition may:

decrease N inputs by 10 to 20%reduces N excretion by 12 to 21%reduces N volatilization by 15 to 33%

Based on annual occupancy, lose 50% of N excreted

• 53.5% annually for control animals, or 103 g/hd/d

• 48.2% annually for phase-fed animals, or 78 g/hd/d

2-year beef study(protein level)

Digestive Process of RuminantsPhosphorus

Rumen

Salivary P

M/O

Sm Intestine

Excess P

Fecal P Productive

functions

Milk(0.085 to 0.1%)

Diet P

Ruminant Nutrition

• Estimated P excretion (dairy):– Dry matter intake– Amount of P in ration– Milk production– Amount of P in milk (~ 0.10%)

Phosphorus

Ruminant Nutrition

• Estimated P excretion (beef):– Dry matter intake– Concentration of P in ration– Days on individual ration– Purchase weight (initial weight)– Market weight (final weight)– Standard reference weight

Phosphorus

TSP Question to Producer• Are the rations reformulated when there are

different ingredient changes?

• Are rations changed at different stages in the

production cycle?

• What is the laboratory analysis schedule for the feed management plan?

• Are by-product feeds being used in the ration?

Dietary P in Feedlot Diets

0.27 0.35

0.520.59

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

85% Corn 85% Corn +Supplement

Byproduct Byproduct +Supplement

% d

iet

P (

DM

-bas

is)

SupplementByproductCornRoughage

NRC

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

P, % of diet DM

AD

G, l

b/da

y

P requirements

NRC corn industry

P Mass Balance: Summer Yearlings

Feedlot Pen

7.2 lb Pintake

1.9 lb P retained5.3 lb

excreted

12.8 lb Pintake

1.9 lb P

retained10.9 lb

excreted0.35% P diet

0.24% P diet

REDUCED44%

Values for the entire feeding period

P Mass Balance: Winter/Spring Calves

Feedlot Pen

9.9 lb Pintake

2.4 lb P retained7.5 lb

excreted

15.0 lb Pintake

2.5 lb Pretained12.5 lb

excreted0.40% P diet

0.26% P diet

REDUCED33%

Values for the entire feeding period

Dietary P effect on excretion

0

10

20

30

40

0 10 20 30 40 50P intake (g/d)

P e

xcre

tio

n (

g/d

)

Y = 0.0111x2 + 0.0522x + 6.6726; r2 = 0.74

2500 10,000 25,000

0 byp 0.29 P 1,320 5,300 13,200

20 byp 0.39 P 1,900 7,600 19,000

40 byp 0.49 P 2,500 10,000 25,000

Land Requirements, 4 yr P basis(acres)

2500 10,000 25,000COSTS0 byp 0.29 P 3.00 2.10 3.0020 byp 0.39 P 3.50 2.70 4.3040 byp 0.49 P 3.90 3.30 5.75NET VALUE0 byp 0.29 P 2.50 3.50 2.5020 byp 0.39 P 4.30 5.10 3.5040 byp 0.49 P 6.10 6.80 4.30

Costs and Net Value, C-SB rotation4-Yr P Basis, ($/hd)

Ration Balancing

Balancing Ruminant Rations

Book values vs Ingredient testing:

• Book values have limited value

• Ingredient testing only as good as the sample taken

Ingredient Challenges

Balancing Ruminant Rations

“Unbreakable Law of Sampling: You never know the true value of anything”

-Bill Weiss, OSU

Ingredient Challenges

Balancing Ruminant Rations

Numbers are not absolute!

Ingredient Challenges

20 tons of feedstuff 1 lb sample

sent to lab

(1/40,000)

1 g sub-sample analyzed

(1/18,000,000)

Balancing Ruminant RationsMeeting the Requirements of the Herd

If herd average is 77 lbs:Overfeeding cows producing 55 lbs

Excess nutrients leads to weight gain leading to health problems and lowered production

Underfeeding cows that could produce 120 lbs Not providing enough nutrients to meet genetic potential Not taking advantage of “money-makers”

Fresh cows producing 77 lbs have different requirements If do not meet nutritional needs of fresh cow, entire

lactation will be negatively affected: lost production and health issues

Who do you balance the ration for?

Feeding Management: The Bottom Line

The milking herd should be grouped by production level so that multiple rations can be formulated over the complete lactation.

Similarly, growing feedlot beef cattle should be grouped by sex, age and production potential so that multiple rations can be fed over the growth period.

Reducing N and P Excretion with Feed Management

Nitrogen Strategies for Dairy

• Increase dry matter uptake.

• Improve forage quality.

• Evaluate balance of types of home grown forages and other feed ingredients available.

• Consider forage protein fraction.

• Consider feeding method (phase and TMR).

• Consider supplemental protein source.

• Monitor blood urea nitrogen (BUN) and milk urea nitrogen (MUN).

Beef Strategies• Test feed for nutrients and dry matter.

• Use supplemental protein to balance RDP and RUP.

• Discontinue supplemental P.

• Consider phase feeding.

• Use available tools to evaluate your rations.

Questions?

P Mass Balance – Example CNMPManure

P2O5 Produced

= (44.82 lbs. avg. feed intake (%dm) x 0.0036*) - (65 lbs. avg. milk prod. per cow/day** x 0.001***) x 2.29****

= 0.0963 lbs. P per day per cow x 2.29

= 0.22 lbs. P2O5 per day per cow x 175 cows x 365 days

= 14,094 lbs P2O5 per year

Acres Required for P2O5 Mass Balance

= 14,094 / 65 lbs. P2O5 removed by crop

= 217 acres X 50% confinement

= 108 acres

*0.36 % of P in total feed ration from feed analysis

**Based on 2000/2001 rolling herd average of 26700 lbs. of milk produced per cow per year

***0.10 % of P in milk; ****conversion of P to P2O5

Class Exercise (Ruminants)• Calculate P excretion for the example

CNMP dairy if they use 25% DDGS in place of corn silage and milled feed.

• Calculate the amount of land needed to apply the P2O5 (assume 65 lbs of P2O5 needed for corn silage/acre) from the manure from cows fed this new ration (assume that only 50% of the time the cows are in confinement)

Class Exercise (Ruminants)• Calculate P excretion for the example

CNMP dairy if they use 25% DDGS in place of corn silage and milled feed.

What do you need to know?

DMI, diet composition, milk production

Class Exercise (Ruminants)• Calculate P excretion for the example

CNMP dairy if they use 25% DDGS in place of corn silage and milled feed.

What do you need to know?

DMI = 44.82 lb per dayDiet composition (DDGS contains 0.90% P, so diet will be 0.51% P)Milk production = 65 lb per day175 cows still

Class Exercise (Ruminants)

• Calculate P205 excretion for the example CNMP dairy with 0.51% P in the diet

• Calculate the amount of land needed to apply the P2O5 (assume 65 lbs of P2O5 needed for corn silage/acre) from the manure from cows fed this new ration (assume that only 50% of the time the cows are in confinement)

Class Exercise (Answer)Manure

P2O5 Produced

= (44.82 lbs. avg. feed intake (%dm) x 0.0051*) - (65 lbs. avg. milk prod. per cow/day** x 0.001***) x 2.29****

= 0.1636 lbs. P per day per cow x 2.29

= 0..375 lbs. P2O5 per day per cow x 175 cows x 365 days

= 23,953 lbs P2O5 per year

Acres Required for P2O5 Mass Balance

= 23,953 / 65 lbs. P2O5 removed by crop

= 368 acres X 50% confinement

= 184 acres

*0.51 % of P in total feed ration from feed analysis

**Based on 2000/2001 rolling herd average of 26700 lbs. of milk produced per cow per year

***0.10 % of P in milk; ****conversion of P to P2O5

Class Exercise (Answer)• Difference in P2O5 produced:

• 23,953 lbs – 14,094 lbs = 9,859 lbs more produced; however, only 50% confinement, so 4,930 lbs collected and stored.

• Difference in acres of land required (assuming 50% confinement):

• 184 acres – 108 acres = 76 acres more needed

• If all the manure was collected (100% confinement, then 151 acres more needed

Computer Software Tools• Dairy Whole Farm Balance Nutrition

Education Tool (WFBNET) – www.puyallup.wsu.edu/joeharrison/software

• Whole Farm Balance – on CNMP Course CD and at http://cnmp.unl.edu

• Nutrient and Land Estimator – on CNMP Course CD and at http://cnmp.unl.edu