Protein Formulation for High Producing Lactating Dairy Cattle: What are our

practical limits?

Mike Van AmburghDepartment of Animal Science

Outline

• What are the efficiencies of nitrogen utilization for lactating dairy cattle and what that mightmean for ration formulation

• Discuss some of what we have learned about nitrogen metabolism

• Some research studies and farm examples

• Summary

• Opportunities exist – need refining• On farm N efficiencies (milk N:feed N)

20 to 32%• Theoretical efficiency limit 40 to 45% in lactating

dairy cattle (Van Vuuren and Meijs, 1987; Hvelplund and Madsen, 1995)

• Practical limit is ~ 38 to 40% (groups are achieving this)

• Requires refinement of current ration formulation models – better balancing for rumen N and post-ruminal amino acids

• Requires refinement of feeding management – reduce variation associated with feed, management

Improving Efficiency of Use of Intake Nitrogen

• Milk protein output is a function of energy supply and amino acid balance

• Urine N is variable and is a function of excess nitrogen intake and recycling

• Urine N is most volatile form – so reducing it will reduce the environmental impact and improve efficiency

• High levels of urinary indicate:– Overfeeding total protein– High rumen N balance relative to microbial

demand

• Can use monitoring tools like milk urea nitrogen to diagnose independent of production responses

Improving Efficiency of Nitrogen Use

Value of the “Safety Factor”• 500 cows • With forage availability, ration can be

balanced at 15% CP for level of production (85 lbs/d, 52.5 lb DMI)

• Nutritionist level decision – “safety factor” – doesn’t want cows to lose milk, doesn’t want to lose customer

• Management considerations - variation• Cost of 15% vs 15.5% in SBM equiv. ~1 lb

= $0.20/cow/d or $36,500/year

Impacts of source and amounts of CP on intestinal supply of N and performance of

cows

Ipharraguerre and Clark, 2005

Urinary N is variable form of excreted N Fecal N is fairly constant

ReferenceIntake N

(g/d)Fecal N

(g/d)Urinary N

(g/d)

Kauffman and St-Pierre, 2001 429 178 93

460 184 101

572 198 190

Hristov and Ropp, 2003 658 208 233

754 176 279

50

100

150

200

250

300

450 500 550 600 650 700 750

Milk

, Uri

ne a

nd F

ecal

N

excr

etio

n, g

/d

Nitrogen Intake, g/d

Milk N

Urinary N

Fecal N

Nitrogen excretion in milk, feces and urine based on N intake in lactating dairy cattle – under controlled conditions of energy as first limiting: 88 lb milk/d @53 lb DMI range in CP intake 14 to 18.7%

CNCPS v6.1 Nutrient Excretion – Manure and Manure Nitrogen

RDP Required in Diet DM

• Determined by the amount and type of fermentable carbohydrates in the diet

• Dairy NRC (2001): 9 – 11% of diet DM

• For diets common to the Northeast: 10.4 – 10.8%

• Rely on feed intake and MUN to make final decision

• MUN levels of 8 to 10 mg/dl are ideal – need to manage well

• CNCPSv6.1 RDP levels as low as 7.6% with good performance – again need to manage well

Blood Urea

N intake

Ammonia

Urinary Urea

Effect of forage preservation method on urea N production and recycling (Ouellet et al., 2004)

• 6 cows, 3x3 Latin square• Diets:

– 60% forage, 40% concentrate (14.5% CP) fed 12x/d

– 3 different forages:• Sun-cured hay, 10.1% CP• Formic acid-treated silage (12.0% CP)• Microbial inoculated silage (12.2% CP)

Diet

Intake N

Urea-N synthesis

Urea-N entering GIT

gN/d gN/d

% of intake

N gN/d

% of intake

NHay 295 172 58% 123 42%

Formic acid treatment

341 171 50% 122 36%

Silage inoculant

351 200 57% 140 40%

Ouellet et al., 2004

Form of forage preservation had little effect on urea N production and recycling

Lysine and Methionine ratios• Current recommendations

• Rulquin• MET: 2.50% of metabolizable protein supply• LYS: 7.30% of metabolizable protein supply• These are similar to 2001 Dairy NRC (2.40

and 7.20%)• Current Recommendations

• MET: >2.20% of MP supply• LYS: >6.80% of MP supply• While maintaining a 3:1 ratio of LYS:MET

• With new implementation of CNCPS v6.1, factorial calculations appear more in line with ratios.

Limiting amino acids in lactating dairy cows

1. Met, Lys, and His identified most often as first limiting (but His is questionable in US diets)

2. Met: when most RUP is provided by oilseed meals, animal-derived proteins, or a combination of the two

3. Lys: when corn or feeds of corn origin provide most or all dietary RUP

4. His: when grass silage, barley and oat diets are fed with or without feather meal as sole source of supplemental RUP

Chuck Schwab

Herd Level Examples of Improved Nitrogen Efficiency

Example Herd A – 54 lb DMI, 92 lb Milk% DM basis CNCPS v6.1

CP 14.4

RDP 8.6

Sol CP 4.9 (34)

Rumen NH3, % req 134

Rumen peptides, % req 143

NDF 31.6

Lys:Met 3.29

ME allowable, lb 99

MP allowable, lb 90

Example Herd Ingredients – 54 lb DMI, 92 lb MilkIngredient DM amount, lb

Corn silage 17

Grass haylage 12

Dry hay 3

Ground corn 13.3

Soybean Meal 4.0

Roasted soybean 1.6

Cane molasses 0.46

Sugar 0.70

Provaal 0.44

Urea 0.097

Meta smart 0.012

Min. & Vitamins 1.59

Total 54.2

% DM basis CNCPS v6.1 output

CP 15.0RDP 8.1Sol CP 4.9 (30)Rumen NH3, % req 104Rumen peptides, % req 110NDF 31.5Lys:Met 2.8ME allowable, lb 94MP allowable, lb 98

Example herd B - 53 lb DMI, 89 lb milk

Example herd B - 53 lb DMI, 89 lb milk Ingredient DM amount, lb

Corn silage 19.5

Alfalfa hay 9.8

Wheat straw 1.0

Flaked corn 6.2

Ground corn 6.2

Soybean Meal 1.9

Amino Plus 2.9

Wheat midds 2.0

Citrus pulp 2.0

Sugar 0.50

Provaal 0.23

Energy Booster 0.35

Urea 0.13

Smartamine and Alimet 0.03

Min. & Vitamins 1.3

Herd C

Current statsDMI 50 lb CP 15.8%NDF 30.2%Actual milk 84 lb ME allowable 83.5 lbMP allowable 91 lbTrue protein 3.1%Fat 3.7%Met 2.3% MPLys 6.77% MP

Herd C

Concentrate mix contains Smartamine and Alimet

Herd C

Herd C

9/1/

2008

9/20

/200

8

10/9

/200

8

10/2

8/20

08

11/1

6/20

08

12/5

/200

8

12/2

4/20

08

1/12

/200

9

1/31

/200

9

2/19

/200

9

3/10

/200

9

3/29

/200

9

4/17

/200

9

5/6/

2009

5/25

/200

9

6/13

/200

9

7/2/

2009

7/21

/200

9

8/9/

2009

8/28

/200

9

9/16

/200

92.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

0

10

20

30

40

50

60

70

80

Milk and Components – Herd BasisP

erc

en

t

9/1/

2008

9/21

/200

8

10/1

1/20

08

10/3

1/20

08

11/2

0/20

08

12/1

0/20

08

12/3

0/20

08

1/19

/200

9

2/8/

2009

2/28

/200

9

3/20

/200

9

4/9/

2009

4/29

/200

9

5/19

/200

9

6/8/

2009

6/28

/200

9

7/18

/200

9

8/7/

2009

8/27

/200

9

9/16

/200

93

4

5

6

7

8

9

10

11

12

13

14

15

Milk Urea Nitrogen – Bulk Tank

What was the impact on N excretion?

Our calculations indicate ~60 g N/cow/d less urinary excretion

1100 cows = ~26.5 tons N less in the environment over 365 d lactation

In 2009, that was $0.40/cow/d reducedfeed costs

Herd Example - D1050 cows – High group characterized

1,542 lb BW

~100 DIM

59.5 lb DMI

15.8% CP

60% Forage

120 lb milk/d

Milk:Feed (Feed efficiency): 1.99

Herd Example - D

NDF, %DM: 30.9

Starch, % DM: 28.7

Sugar, % DM: 5.4

Ether extract, % DM: 5.1

%Forage: 60.1

Forage NDF, %BW: 0.94

Herd Example - D

Productive N : N Intake – 38%!

Remember – most farms are 25 to 30%

Productive N: Urinary N – 1.33:1

Most farms are 0.6 to 0.8:1

Summary:

We have the opportunity to lower protein intakes to reduce the environmental impact of dairy farms and improved income over feed costs

We are getting better at balancing at the limits of protein requirements for lactating cows

As we approach the absolute requirement, it provides us with the opportunity to estimate the opportunity cost of feed and nutrient management

Any effort to do this will require greater intensity of management and adherence to SOP’s