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
Overview of Presentation
 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
Dairy Production in Ireland
 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
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
296
303
307
344
-
Starch
Results
Pasture Dry Matter Intake
16
n.s.
Pasture DMI (kg d-1)
14
12
10
8
6
4
2
0
HP
LP
Concentrate Type
LP+HMBi
LP Maize
Weekly Milk Yield
34
Milk Yield kg d-1
32
HP vs. LP (P < 0.05)
Week (P < 0.01)
Week x Trt. (P < 0.05)
30
28
26
24
22
20
18
16
1
2
3
4
HP
5
LP
6
7
8
9
Week Postpartum
LP+ HMBi
10
11
LP Maize
12
13
14
Energy Intake
ns
20
18
Intake(UFL d-1)
16
14
12
10
8
6
4
2
0
Concentrate Type
HP
LP
LP+ HMBi
LP Maize
Energy Corrected Milk
40
35
a
ab
b
30
ECM (kg d-1)
ab
25
20
15
10
5
0
Concentrate Type
HP
LP
LP+ HMBi
LP Maize
a vs. b, P < 0.05
Energy Balance
Energy Balance (UFL d-1)
0.6
ns
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
Concentrate Type
HP
LP
LP+HMBi
LP Maize
Blood Metabolites
Blood Urea Nitrogen
Blood Urea N (mmol L-1)
7
a
6
5
b
b
b
4
3
2
1
0
HP
LP
Concentrate Type
LP+ HMBi
LP Maize
Beta Hydroxy Butyric Acid
0.8
a
βHBA (mmol L-1)
0.7
b
b
0.6
b
0.5
0.4
0.3
0.2
0.1
0
HP
LP
Concentrate Type
LP+ HMBi
LP Maize
a vs. b (P < 0.05)
NEFA (mmol L-1)
Non Esterified Fatty Acids
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
a
ab
ab
b
HP
LP
Concentrate Type
LP+ HMBi
LP Maize
a vs. b (P < 0.05)
Glucose
4
Glucose (mmol L-1)
3.5
b
b
ab
a
3
2.5
2
1.5
1
0.5
0
HP
LP
Concentrate Type
LP+ HMBi
LP Maize
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
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
Composition (% unless stated)
Results
Dry Matter Intake over the Duration
of the Experiment
22
Intake (kg DM d-1)
20
18
16
14
12
10
1
2
3
4
5
6
Week of Lactation
HP-LS
LP-HS
7
8
9
Diet P = 0.25
Week P < 0.01
Diet x Week P = 0.17
Daily Milk Yield for the Experiment
34
Milk Yield (kg/ d)
32
30
28
26
24
P < 0.01
22
20
Diet
HP-LS
LP-HS
Milk Constituent Yield (kg/ d)
Milk Constituent Yield
1.4
1.2
1
0.8
0.6
P < 0.01
P < 0.01
0.4
P < 0.01
0.2
0
Fat
Protein
HP-LS
LP-HS
Casein
305d Lactation Yield
8000
Milk Yield (kg d-1)
7000
6000
5000
Fat (Kg)
4000
Protein (Kg)
3000
HP-LS
LP-HS
349P = 0.99
334
255
261
2000
1000
0
Diet
HP-LS
LP-HS
Energy Balance over the Duration of
the Experiment
Energy Balance (UFL/ d)
4
3
2
1
0
-1
-2
-3
-4
1
2
3
4
5
6
Week of Lactation
HP-LS
LP-HS
7
8
9
Diet P = 0.02
Week P < 0.01
Diet x Week P = 0.75
BCS Units
BCS at Calving and Day 63
3.6
3.2
2.8
2.4
2
1.6
1.2
0.8
0.4
0
Loss = 0.2 BCS
P = 0.47
P = 0.36
BCS at Calving
HP-LS
BCS at d63
LP-HS
Blood Metabolites
Beta Hydroxy Butyric Acid
0.9
0.8
BHBA (mmol/ L)
0.7
0.6
0.5
0.4
P = 0.03
0.3
0.2
0.1
0
Diet
HP-LS
LP-HS
NEFA (mmol/ L)
Non Esterified Fatty Acids
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
P = 0.54
Diet
HP-LS
LP-HS
Glucose
3.5
Glucose (mmol/ L)
3
2.5
2
P = 0.36
1.5
1
0.5
0
Diet
HP-LS
LP-HS
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