Using dietary crude protein to manipulate energy balance

Using dietary crude protein to manipulate

energy balance in early lactation dairy cows

S.J. Whelan1,3, F.J. Mulligan2B. Flynn3, J.J. Callan3 and K.M. Pierce1 1School of Agriculture and Food Science and 2School of Veterinary Medicine

University College Dublin, Belfield, Dublin 4

3UCD Lyons Research farm, Newcastle, Dublin, Ireland

Introduction

Dairy production in Ireland

Nutritional issues of the early lactation dairy cow

Recent energy balance experiments conducted at UCD

Effect of supplementary concentrate type on energy balance in the

early lactation, pasture fed dairy cow

Effect of dietary CP and starch content on energy balance in early

lactation dairy cows

Conclusions

Overview of Presentation

Largely seasonal production system

1.1 million dairy cows

5,000 kg average milk production

Contributes €2.7 billion to Irish exports

However, still room for improvement…

Replacement rate is 25%

15% are replaced due to infertility

Calving interval is 394 days

Dairy Production in Ireland

Nutritional issues of the early lactation dairy cow

• Early lactation is a challenging period for the dairy cow

• Important to explore dietary strategies that reduce these challenges

• Optimising DMI is important in improving energy balance

• Moderating milk yield through dietary CP may also improve energy

balance

Manipulating CP intake in the pasture fed early

lactation dairy cow

Basis for Experiment

Pasture is the most abundant forage source available to Irish

dairy farmers

However…

– Chemical composition of grass can vary considerably

– This flux in nutrient supply may be detrimental to the animals health

Therefore…

– Concentrate supplementation is often required, but…

– Concentrate type will be important

Materials and Methods

Randomised block design

Day 1 until day 100 postpartum

11 animals per dietary treatment

Balanced for parity, milk yield, constituent yield and calving

date

Blood samples harvested on weeks 2 through to 5 postpartum

Milk samples taken weekly

Energy balance determined during week 6 post partum

Concentrate Treatments

Supplements were fed twice daily during milking (6kg total)

4 supplementary concentrate treatments

HP(180g CP kg-1, rolled barley)

LP(140g CP kg-1, rolled barley)

LP+ HMBi (140g CP kg-1, rolled barley + supplementary

methionine (HMBi))

LP Corn (140g CP kg-1, ground maize grain)

Chemical Composition of diets offered

HP LP LP+HMBi LP Maize Pasture

DM (g kg-1) 867 858 862 859 207

Energy (UFL) 1.12 1.10 1.10 1.14 0.98

Crude protein 192 150 150 150 170

PDIA 72 52 52 74 39

PDIN 145 108 108 122 107

PDIE 139 120 120 133 98

NDF 219 218 222 223 438

ADF 91 106 111 115 219

ADL 7 10 12 7 63

Ash 87 81 80 79 73

Starch 296 303 307 344 -

Results

Pasture Dry Matter Intake

0

2

4

6

8

10

12

14

16

Concentrate Type

Pa

stu

re D

MI

(kg d

-1)

HP LP LP+HMBi LP Maize

n.s.

Weekly Milk Yield

16

18

20

22

24

26

28

30

32

34

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Mil

k Y

ield

kg d

-1

Week Postpartum

HP LP LP+ HMBi LP Maize

HP vs. LP (P < 0.05) Week (P < 0.01) Week x Trt. (P < 0.05)

Energy Intake

0

2

4

6

8

10

12

14

16

18

20

Concentrate Type

Inta

ke(U

FL

d-1

)

HP LP LP+ HMBi LP Maize

ns

Energy Corrected Milk

0

5

10

15

20

25

30

35

40

Concentrate Type

EC

M (

kg d

-1)

HP LP LP+ HMBi LP Maize

ab b

a ab

a vs. b, P < 0.05

Energy Balance

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

En

ergy

Bala

nce

(U

FL

d-1

)

Concentrate Type

HP LP LP+HMBi LP Maize

ns

Blood Metabolites

Blood Urea Nitrogen

0

1

2

3

4

5

6

7

Concentrate Type

Blo

od

Urea N

(m

mol

L-1

)

HP LP LP+ HMBi LP Maize

a

b b b

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Concentrate Type

βH

BA

(mm

ol

L-1

)

HP LP LP+ HMBi LP Maize

a

b

b b

a vs. b (P < 0.05)

Beta Hydroxy Butyric Acid

Non Esterified Fatty Acids

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Concentrate Type

NE

FA

(mm

ol

L-1

)

HP LP LP+ HMBi LP Maize

a ab

b ab

a vs. b (P < 0.05)

Glucose

0

0.5

1

1.5

2

2.5

3

3.5

4

Concentrate Type

Glu

cose

(mm

ol

L-1

)

HP LP LP+ HMBi LP Maize

b b ab a

a vs. b (P < 0.05)

Conclusions

• Milk yield was reduced where LP was offered. However…

– ECM was not different

• Lower BHBA and blood urea N indicated a more favourable

metabolic status where low CP concentrates were offered

• The use of maize grain or supplementary methionine in low CP

concentrates improved milk production without impacting on

metabolic status

Dietary manipulation of crude protein and starch content

affects energy balance in early lactation dairy cows

Basis for Experiment

• Early lactation is a challenging period for the dairy cow

• Reducing dietary CP intake can improve EB

• Similarly providing glucogenic diets can improve the

metabolic status of the diary cow

• However, the simultaneous application of these strategies has

not been tested to date

Materials and Methods

• Randomised block design

• Day 1 until day 63 postpartum

• 10 animals per dietary treatment

• Balanced for milk yield, constituent yield and calving date

• Blood samples harvested on days 0, 7, 14, 21, 28, 35 and 63

• Milk samples taken weekly

• Post experiment

• All animals offered a pasture based diet

Dietary Treatments

• Diets were offered once daily as a TMR

1. High CP low starch TMR (HP-LS)

– 15% CP

– 6% Starch

2. Low CP high starch TMR (LP-HS)

– 12% CP

– 28% Starch

• Diets were iso-energetic (1.05 UFL/ kg DM)

Chemical Composition of diets

offered HP-LS LP-HS

Composition (% unless stated)

DM 29.3 37.3

UFL/ kg DM 1.05 1.05

CP 14.6 11.9

NDF 54.5 39.3

PDIA 4.0 3.8

PDIN 8.9 7.8

PDIE 9.4 9.3

ADF 35.1 25.3

ADL 4.1 2.9

NDF for. 32.2 27.4

Ash 7.5 5.7

Starch 5.7 27.5

Results

Dry Matter Intake over the Duration

of the Experiment

10

12

14

16

18

20

22

1 2 3 4 5 6 7 8 9

Inta

ke

(kg D

M d

-1)

Week of Lactation

HP-LS LP-HS

Diet P = 0.25

Week P < 0.01

Diet x Week P = 0.17

20

22

24

26

28

30

32

34

Diet

Mil

k Y

ield

(k

g/

d)

HP-LS LP-HS

P < 0.01

Daily Milk Yield for the Experiment

Milk Constituent Yield

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Fat Protein Casein

Mil

k C

on

stit

uen

t Y

ield

(k

g/

d)

HP-LS LP-HS

P < 0.01 P < 0.01

P < 0.01

P = 0.99

305d Lactation Yield

0

1000

2000

3000

4000

5000

6000

7000

8000

Diet

Mil

k Y

ield

(k

g d

-1)

HP-LS LP-HS

HP-LS LP-HS

Fat (Kg) 349 334

Protein (Kg) 255 261

Energy Balance over the Duration of

the Experiment

Diet P = 0.02

Week P < 0.01

Diet x Week P = 0.75

-4

-3

-2

-1

0

1

2

3

4

1 2 3 4 5 6 7 8 9

Ener

gy

Bal

ance

(U

FL

/ d)

Week of Lactation

HP-LS LP-HS

0

0.4

0.8

1.2

1.6

2

2.4

2.8

3.2

3.6

BCS at Calving BCS at d63

BC

S U

nit

s

HP-LS LP-HS

P = 0.47

BCS at Calving and Day 63

P = 0.36

Loss = 0.2 BCS

Blood Metabolites

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Diet

BH

BA

(mm

ol/

L)

HP-LS LP-HS

Beta Hydroxy Butyric Acid

P = 0.03

Non Esterified Fatty Acids

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Diet

NE

FA

(mm

ol/

L)

HP-LS LP-HS

P = 0.54

Glucose

0

0.5

1

1.5

2

2.5

3

3.5

Diet

Glu

cose

(mm

ol/

L)

HP-LS LP-HS

P = 0.36

Conclusions

• Offering early lactation dairy cow a low CP, high starch diet

improves energy balance

• Reductions in milk yield observed during early lactation did

not affect 305 d lactation yields

• Blood metabolites did not indicate a severe metabolic

challenge in this experiment

Overall Conclusions

• Regardless of production system, the maintenance of DMI is

key in maintaining a more positive energy balance

• Reducing CP intake moderates milk production and reduces

the urea burden on the animal, thus reducing energy demands

• Further work is required in pasture based production systems

to determine the extent to which CP can be reduced

• Work is also required to determine the lifetime effects of these

strategies on the survival of the dairy cow

Acknowledgements

This research was funded under the National Development Plan

through the Research Stimulus Fund administered by the Irish

Department of Agriculture, food and Marine

Additionally I would like to acknowledge the assistance of the

farm and laboratory staff at UCD Lyons Research Farm

Thank You for your time