1. When formulating diets for pens of cows, it is important to consider the variation in milk production and dry matter intake within the pen. Accounting for this variation can improve accuracy. 2. For pens without fresh cows, the maximum allowable milk from the diet using metabolizable protein should be the pen average milk production plus one standard deviation. 3. For diverse pens containing fresh cows, the diet should support a higher milk production level, such as the pen average plus 1.5 standard deviations or 24% above the average, to adequately meet the needs of the fresh cows.

1. Formulating a
diet for a pen of
cows
Not a single cow
Bill Weiss
Animal Sciences
Wooster

2. Potential Grouping Strategies
1. Production 4. Repro status
2. Parity 5. Keep pens full
3. Stage of lactation 6. etc.
1. Average and distributions of milk yields
2. Average and distributions of DMI
1. Cow inputs for formulation software
2. DM intake estimates and inputs

3. Requirement: A pen vs. A cow
0
5
10
15
20
25
30
35
40
5 15 25
Numberofcows
Requirement X/day
40 45 50 55 60

4. Requirement: A pen vs. A cow
0
5
10
15
20
25
30
35
40
5 15 25
Numberofcows
Requirement X/day
40 45 50 55 60
XDMI
DMI

5. Distributions will differ
(will you even know it?)
0
5
10
15
20
25
30
35
40
Should (will?) distribution affect
formulation inputs?

6. Major Factors Affecting Requirements
0
5
10
15
20
25
30
35
40
45
Mcalorlbs/d
900 lbs
1500 lbs
50 lbs/d
100 lbs/d
NEL MPMP NEL
BW
@75 lbs/d
Milk @
1200 lbs1. Milk yield
2. BW
3. 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

7. 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

8. 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

9. 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 ???

10. 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

11. 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 !

12. 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
Milkresponse

13. Protein Requirements for a Group of
Cows
0
5
10
15
20
25
30
35
40
5 15 25
Numberofcows
Protein Requirements
1 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

14. 110 Cows
Avg = 75 lbs
SD = 13
Distribution of Milk Yields in One Pen of
Holstein Cows
35
lbs
130
lbs

15. 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

16. For a Pen without Fresh Cows
MP and NEL for Avg Cow is adequate for
about 1.15 X avg milk
If average = 75 lbs/d
Diet will support 75 x ~1.15
= 85 to 90 lbs/d
What about other nutrients?

17. 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

18. 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 cow
Function of DMI, not milk

19. 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
DMI,lbs/day
Rumen Degradable Protein, % of DM
Cyriac et al., 2008
NRC
All Pens
10-10.5% RDP*
(slightly more than
req’t)
* Calculated with
NRC model

20. Feed
Environmental
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.

21. MP specs for a pen with no fresh cows
These Cows will be
fed if formulated for
mean
~ 1 SD
Avg = 75 lbs
SD = 13
MP-milk = 88lbs
These cows will be
fed if MP-allow milk
= Mean + 1 SD
Avg*1.15

22. 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 Target
10 lbs 95 lbs
15 lbs 100 lbs
20 lbs 105 lbs
Reflects typical within herd variation
(CV=16%) (Finney et al., 2013)

23. Groups without Fresh Cows: Digestible
RUP (MP)
Use pen average DMI
Max MP allowable milk = Mean + 1 SD
If SD not known: Assume SD = < 0.16*mean
May need to lower because feed cost/regulations
Diet For High Pen
Pen DMI = 58 lbs
Pen average milk = 90 lbs
Pen SD = ? (assume 90*0.16 = 14.4 lbs)
MP-allowable milk should = 90+14 = 104 lbs

24. 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

25. Avg DIM = 178
(6 months)
Distribution of Lactation Stage in One
Pen of Holstein Cows
<
These guys
don’t fit

26. Diverse Pens with Fresh Cows:
Digestible RUP (MP)
Depends on how many fresh cows
Should bias toward the fresh cow
Simulation Results
Assumed 10% fresh cows (<25 DIM)
Assumed typical lactation curve
Use Pen Average DMI
MP-allowable milk should ~Avg+1.5 SD
or Average *1.24 (i.e., 16*1.5)

27. 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

28. 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 SD
if SD unknown = Avg*1.16

29. 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

30. OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER
http:// dairy.osu.edu