1. Epidemiology and Management of
BRD in Dairy Heifer Replacements
Alex Bach,1,2
1IRTA-Department of Ruminant Production
2ICREA, Institut de Recerca i Estudis Avancats
Veterinarians represent a major piece in the
sustainability chain:
Provide management advice
Care for the environment
Ensure economical performance of the herd
Foster data collection and use records to
make management decisions
THE SUSTAINABLE VET
Introduction
0
15
30
45
60
Feed Labor Replacement Fixed costs Maintenance Misc. Energy
3.9
4.95.0
7.6
8.7
16.8
53.1
%
Introduction

2. Examine the operation holistically
Identify bottle necks and remove them
Introduction
Reducing AFC (w/o compromising BW at calving)
implies:
1) the number of animals needed
2) the number of days on feed
100 x .30 x ((1-.03)x(1-.01)) x 2x(24/24) = 58 -> 46,000 €
100 x .30 x ((1-.03)x(1-.01)) x 2x(28/24) = 67 -> 53,000 €
100 x .30 x ((1-.03)x(1-.01)) x 2x(22/24) = 52 -> 41,000 €
Number of cows x replacement rate x ((1-mortality) x (1-heifer
culling rate)) x 2x(Age first calving/24)
Introduction
For every kg of BW at calving, one could
expect 14.5 l more milk in the first lactation
(70 Kg of BW mean 1,000 l of milk).
Bach et al., 2008
Introduction

3. For every 100 g ADG during the first 2
months of life, one could expect additional
300 l of milk in the first lactation.
Bach et al., 2008
Introduction
Item 1 2 3 4 5 6 7 8 9 10 11
Age range, d 1-65 66-110 111-158 159-229 230-307 308-336 337-415 416-483 484-546 547-639 640-660
Target BW, kg 80 125 175 250 325 530 390 454 510 590 610
Introduction
Item 1 2 3 4 5 6 7 8 9 10 11
Age range, d 1-65 66-110 111-158 159-229 230-307 308-336 337-415 416-483 484-546 547-639 640-660
Target BW, kg 80 125 175 250 325 530 390 454 510 590 610
Introduction

4. ZONE 1 ZONE 2
BRD Incidence
n=2,771 0 1 2 3 > 4 P-value
Final BW, kg 624 618 624 625 598 0.21
Final age, d 661 665 671 666 670 0.03
BRD
700
750
800
850
900
0 1 2 3 ≥4
Accumulated DIM
Number BRD
Bach, 2010
BRD Incidence
Heifers with 4 or more BRD cases had 1.87 greater
odds of not finishing first lactation than heifers with no
BRD history.

5. Immune status of the animal (colostrum)
Vaccination program
Medication
Management
BRD Incidence
Immune Status
n=204 Low High P-value
BW at exit of Z1, kg 80.4 80.4 0.98
ADG in Z1, kg/d 0.7 0.7 0.91
BW at exit of Z2, kg 126.7 125.8 0.65
ADG in Z2, kg/d 1.0 1.0 0.52
BW at exit of Z3, kg 167.5 167.5 0.97
ADG in Z3, kg/d 0.8 0.9 0.63
Immune Status

6. The risk of having respiratory problems was only 8% lower
in the animals with a high serum protein level compared to
calves with a low protein serum level (P = 0.61).
Similarly, there were no differences in the incidence of
diarrhea between the two groups.
Under the conditions of RLN, the use of serum protein
levels provided no indication of risk of future pathologies or
impaired performance.
Good management and environmental conditions may
overcome immune deficiencies.
Immune Status
5 calves per hutch: 3 m2 and 7 m3 per calf
6 calves per hutch: 2.5 m2 and 5.7 m3 per calf
7 calves per hutch: 2.1 m2 and 5 m3 per calf
- 16.6%
- 28.5%
BRD
7
6
5
0 15 30 45 60
22
38
58
Respiratory afflictions, %
Numberofcalves/pen
Item 5 6 7
n 50 60 70
BW entrance, kg 80 79 79
BW exit, kg 114 117 113
ADG, g/d 830 899 867
BRD

7. General recommendations for calf rearing advocate for
keeping the animals individually housed and feeding milk
replacer (or waste milk) twice daily.
The main purpose of keeping calves individually is to
minimize the spread of infectious diseases (mainly diarrhea
and pneumonia).
A recent survey (Fulwider et al., 2008) indicated that 50% of
the producers send their calves to contract heifer operations.
BRD
The implementation of management schemes that reduce the
spread of calf diseases is even more important in contract
heifer operations (where animals from different origins are
commingled).
Weaning time has been traditionally considered as a stressful
moment for calves.
A common recommendation extensively implemented in the
field is to keep calves individually-housed for at least one
additional week after weaning (Quigley, 2001).
To our knowledge, there is no scientific evidence of the
advantages or consequences of such a practice.
BRD
Several studies have evaluated the impact of weaning calves
in groups or individually on performance (Terre et al., 2006),
behavior (Warnick et al., 1977; Keil and Langhans, 2001), and
health (Svensson and Liberg, 2006; Terré et al., 2006).
These studies have kept the animals either individually- or
group-housed throughout the study.
An alternative weaning strategy would consist on keeping
calves individually-housed for a period of time and, then form
groups of calves for another period of time, and finally wean
them while in groups.
BRD

8. Experiment 1. To evaluate whether allowing calves to remain
for an additional 6 d individually-housed after weaning was
beneficial in terms of performance and respiratory problems.
Experiment 2. To evaluate the effect on performance and
incidence of disease of moving calves in groups before
weaning.
BRD
Materials and Methods (Exp. 1)
Three hundred and twenty female Holstein calves were
assigned to two different treatments:
Allowing the calf to remain individually housed for an
additional 6 d after weaning
Move the calf immediately after weaning to a different pen
forming groups of 8 contemporaneous calves.
Individually Housed
Group HousedIndividually Housed
Starter..4 L of MR 2 L of MR Dry TMR
Starter..4 L of MR 2 L of MR
49 d 56 d 62 d
Group Housed
Dry TMR
98 d
104 d
Results (Exp. 1)
0
17.5
35
52.5
70
Grouped 6 d after weaning Grouped at weaning
41.4
61.2
1.691.72
Before Grouping After Grouping
Proportionofcalvesaffected,%
a
b
Incidence of Respiratory Problems
Bach et al., 2010

9. Materials and Methods (Exp. 2)
Two hundred and forty female Holstein calves were assigned
to two different treatments in three different periods:
Remained until the age of 56 d individually housed
Moved to groups of 8 calves in super-hutches at 49 d of
age
Group HousedIndividually
Group HousedIndividually Housed
..4 L of MR
..4 L of MR
49 d 56 d 63 d 112 d70 d
Starter
Starter
Dry TMR
Dry TMR
2 L of MR
2 L of MR
Materials and Methods (Exp. 2)
Results (Exp. 2)
1.2
1.8
2.4
3
3.6
49-56 57-63 63-70 71-77
3.36
2.73
2.3
1.57
3.42
2.81
2.41
1.79
Grouped at 49 d Grouped at 56 d
Solidfeedintake,kg/d
Age, d
P < 0.05
*
Grouped calves consumed more solid feed than
those individually housed.

10. Results (Exp. 2)
Grouped at 49 d
Grouped at 56 d
15 18 21 24 27
25.8
25.2
Proportion of calves affected, %
0 0.325 0.65 0.975 1.3
1.23
0.87
Cases/calf
P < 0.05
Incidence of Respiratory Problems
Bach et al., 2010
Can we use records to cope with BRD?
BRD
Materials and Methods (Exp. 1)
Two hundred and forty female Holstein calves were raised in
individual hutches and were checked for respiratory afflictions
once daily starting at 5 d of age.
At weaning time calves were allocated into different groups of 8
calves based on their previous BRD history. Within each period,
2 superhutches housed:
8 calves with no previous record of BRD
6 animals with no previous BRD record and 2 calves with
previous episode of BRD
5 calves without a history of BRD and 3 calves with previous

11. 0
13.75
27.50
41.25
55.00
Cases/hutch Calves affected, % Time to 1st case, d
11
52
9
11
38
5
23
24
4
0-8 2-6 3-5
Ratio
No previous case-Previous case
Bach et al., 2010
BRD
Materials and Methods (Exp. 2)
Two hundred and forty female Holstein calves were raised in
individual hutches.
Calves with no previous record of BRD were randomly
allocated to 3 superhutches containing 8 calves
Calves with a previous case of BRD were randomly allocated
to 3 different superhutches (RRR).
0
13.75
27.50
41.25
55.00
Cases/hutch Calves affected, % Time to 1st case, d
9
99
11
19
38
4
0-8 8-8
Ratio
No previous case-Previous case
Bach et al., 2010
BRD

12. 120.00
125.50
131.00
136.50
142.00
Final BW, kg
136
141
0-8 8-8
Ratio
No previous case-Previous case
1.12
1.15
1.17
1.20
1.22
ADG, kg/d
1.13
1.21
Bach et al., 2010
BRD
0.9
1.025
1.15
1.275
1.4
0 1 2 3 ≥4
ADG, kg/d
Bach et al., 2010
120
127.5
135
142.5
150
0 1 2 3 ≥4
BW, kg
BRD
Materials and Methods
140 Holstein calves were housed in individual hutches until 49 d
of age and moved to super-hutches in groups of 8-10 animals.
The Control group did not receive any antibiotic treatment I.M.
unless needed.
Calves in the Zactran group were treated with gamithromycin
at 6 mg/kg (1 mL/25kg BE) one week after being moved from
individual to group housing (at the age of 56 d).

13. 0
0.3
0.6
0.9
1.2
BRD Incidence Cases/calf
0.74
0.452
1.16
0.449
Control Zactran
BRD
P = 0.18
There were no differences (P = 0.81) in growth rate
Materials and Methods
157 Holstein calves were housed in individual hutches until 52 d
of age.
At weaning they were moved to super-hutches in groups of 8-10
The Control group did not receive any antibiotic treatment
unless needed.
The calves in the other group were treated with gamithromycin
at 6 mg/kg (1 mL Zactran/25 kg BW) at the time of movement
from individual to group housing at the age of 56 d.
0
0.225
0.45
0.675
0.9
BRD Incidence Cases/calf
0.44
0.301
0.81
0.516
Control Zactran
BRD
P < 0.05
There were no differences (P = 0.62) in growth rate

14. Combining the results from Experiments 1 and 2 the overall
response to Zactran could be assessed with a bit more
precision (more than 300 animals).
Overall, there were no differences (P = 0.38) in animal
performance between the Control (1.2±0.04 kg/d) and
Zactran (1.2±0.04 kg/d) calves.
The incidence of respiratory problems was greater (P <
0.05) in Control (49.5±0.04 %) than in Zactran (37.0±0.04
%) calves.
The number of respiratory cases per calf was also greater
(P < 0.05) in Control (1.0±0.18 cases/calf) than in Zactran
(0.60±0.18 cases/calf) calves.
BRD
Conclusions
Monitoring health aspects is crucial
BRD incidence my compromise overall productive life of dairy
cows
Action must be taken rapidly
Start with symptomatic treatment and move to antibiotic if no
response is seen
Use an adequate vaccination program
Calves that are moved to groups immediately after weaning
grow better and have less BRD incidence than those that are
kept isolated for one additional week.
Calves that are grouped at pre-weaning time and continue to
receive MR in groups improve ADG, solid feed intake, and
suffer less BRD relapses.
Offering milk in groups does not affect CV of BW or ADG.
Conclusions

15. Thank you