Formulating a diet for a pen of cows

Not a single cow

Bill WeissAnimal SciencesWooster

Potential Grouping Strategies

1. Production 4. Repro status2. Parity 5. Keep pens full3. Stage of lactation 6. etc.

1. Average and distributions of milk yields2. Average and distributions of DMI

1. Cow inputs for formulation software2. DM intake estimates and inputs

Requirement: A pen vs. A cow

0

5

10

15

20

25

30

35

40

5 15 25

Nu

mb

er

of

cow

s

Requirement X/day

40 45 50 55 60

Requirement: A pen vs. A cow

0

5

10

15

20

25

30

35

40

5 15 25

Nu

mb

er

of

cow

s

Requirement X/day

40 45 50 55 60

XDMI

DMI

Distributions will differ(will you even know it?)

0

5

10

15

20

25

30

35

40

Should (will?) distribution affect formulation inputs?

Major Factors Affecting Requirements

0

5

10

15

20

25

30

35

40

45

Mca

lor

lbs/

d

900 lbs

1500 lbs

50 lbs/d

100 lbs/d

NEL MPMP NEL

BW@75 lbs/d

Milk @ 1200 lbs1. Milk yield

2. BW3. Milk composition

4. Parity (growth)

+11%

+1%

+64%

+55%

3.3 F/2.7P vs 4.2F/3.2P~+13% NEL and MP

1.6 lbs/d vs 0~+10% NEL and MP

but also BW difference

Major Factors Affecting DMI within a Herd

BW

Milk yield

Similar to relationships to requirements

Days in milk

- Essentially no independent effect on requirements

- Huge effect on DMI

Milk and DMI (>1 Lactation)

30

40

50

60

70

80

90

100

110

0 20 40 60 80 100 120 140

Lbs/

day

Days in Milk

DMI

Milk+20%

unpub

46 lbs

CP intake: – 700 g NELI: -6 Mcal

55 lbs

Nutrient Requirements and DMI estimates

Typical within pen ranges in:

- BW: Small effect

- Milk comp: Small effect

- Parity: Small effect

- Milk yield: BIG effect

- DIM: Can have BIG effect

Use pen/herd mean

Use mean

Use mean

Use ???

Use ???

When formulating for a pen:

Does the pen include fresh cows(< 3 or 4 Weeks) ?

If pen is just fresh cows-intake, intake, intake more than milk-did I mention, intake, intake, intake

If pen does not have fresh cows- it’s a lot easier

If pen has both- Nutritionally inefficient- Can’t forget early diet effects on peak

What Milk Yield Should be Used for a Group of Post-Fresh Cows ?

Formulating to meet requirements for the average cow usually reduces pen average milk yield

The 11th Commandment:Don’t formulate for the average cow !

45

47

49

51

53

55

57

59

61

63

65

4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4 6.6 6.8 7 7.2 7.4

Hypothetical Response Function

% Protein

Milk

res

po

nse

Protein Requirements for a Group of Cows

0

5

10

15

20

25

30

35

40

5 15 25

Nu

mb

er

of

cow

s

Protein Requirements1 2 3 4 5 6 7 8 9

If you feed the average cowYou don’t

increase milk for the 50% of cows

<average

Milk will drop for the 50% of cows

producing > average

110 CowsAvg = 75 lbsSD = 13

Distribution of Milk Yields in One Pen of Holstein Cows

35 lbs

130 lbs

Distribution of Milk Yields in One Pen of Holstein Cows

If all cows past peak DMI, “avg” diet would meet or exceed requirements for ~80% of cows

~90 lbs

For a Pen without Fresh Cows

MP and NEL for Avg Cow is adequate forabout 1.15 X avg milk

If average = 75 lbs/dDiet will support 75 x ~1.15

= 85 to 90 lbs/d

What about other nutrients?

Diverse Pens and pens w/o Fresh Cows

1. Minerals and vitamins:• Not highly dependent on yield• Use safety factor for uncertainty and

antagonism• 1.2 to 1.5 X NRC is usually adequate

2. Fiber (NDF):• Complicated• First, feed mgmt, NDF/starch source, etc• Second, pen demographics• More cows Milk and DIM, then NDF

Rumen Degradable Protein (RDP)

- Important for optimal rumen function- Relatively inexpensive- Can stimulate DMI- Excess may impair repro- Excess increases manure N

Bacterial requirement, not cowFunction of DMI, not milk

Inadequate RDP can limit microbial growth, fiber digestion, and DMI

40

42

44

46

48

50

52

54

56

58

7 8 9 10 11 12

DM

I, lb

s/d

ay

Rumen Degradable Protein, % of DM

Cyriac et al., 2008

NRC

All Pens10-10.5% RDP*

(slightly more than req’t)

* Calculated with NRC model

FeedEnvironmental

Digestible RUP (MP)

Inadequate MP (dRUP) will reduce milk (body stores are limited)

vs.

Modest excess MP inflates feed costs and increases N in manure

Feed for average

Feed for >Avg

Milk

vs.

MP specs for a pen with no fresh cows

These Cows will be fed if formulated for

mean

~ 1 SD

Avg = 75 lbsSD = 13MP-milk = 88lbs

These cows will be fed if MP-allow milk = Mean + 1 SD

Avg*1.15

Grouping by production (post-fresh) reduces pen variation and will reduce

MP-milk targets

Example: Pen average milk = 85 lbs

Pen SD MP-Allow Milk Target10 lbs 95 lbs15 lbs 100 lbs20 lbs 105 lbs

Reflects typical within herd variation (CV=16%) (Finney et al., 2013)

Groups without Fresh Cows: Digestible RUP (MP)

Use pen average DMIMax MP allowable milk = Mean + 1 SDIf SD not known: Assume SD = < 0.16*meanMay need to lower because feed cost/regulations

Diet For High PenPen DMI = 58 lbsPen average milk = 90 lbsPen SD = ? (assume 90*0.16 = 14.4 lbs)MP-allowable milk should = 90+14 = 104 lbs

Diverse Groups without Fresh Cows: NEL

Theoretically, NEL allowable milk = avg. milk- above average cows will lose BC- below average cows gain it back

Recommendation

1. At pen average DMI, NEL-allowable milk should equal ~1.1 X average milk

2. Adjust based on changes in BCS

Avg DIM = 178(6 months)

Distribution of Lactation Stage in One Pen of Holstein Cows

<

These guys don’t fit

Diverse Pens with Fresh Cows: Digestible RUP (MP)

Depends on how many fresh cowsShould bias toward the fresh cow

Simulation ResultsAssumed 10% fresh cows (<25 DIM)

Assumed typical lactation curve

Use Pen Average DMIMP-allowable milk should ~Avg+1.5 SD

or Average *1.24 (i.e., 16*1.5)

Early Lactation Group (< 25 DIM)

Primary Goal:

1. Adequate (extra?) RDP

2. Moderate NDF (~30%) and starch (~25%)

3. Highly digestible NDF

4. Lots of bunk space

5. Don’t worry about NEL, get cows to eat

MAXIMIZE DMI

Summary

- Keep fresh cows (< ~21 DIM) in a separate group and formulate that pen for DMI

- For pens without fresh cows•Knowing within pen variation in milk

increases formulation accuracy

•Max MP-allowable milk = Avg + 1 SDif SD unknown = Avg*1.16

Summary

- For diverse pens with fresh cows• Greater overfeeding is necessary • Increased feed costs• Max MP allowable milk = Avg + 1.5 SD

or if SD unknown: =Avg * 1.24

OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER

http:// dairy.osu.edu