Transcript Infectious disease triad - Range Beef Cow Symposium XXII

Managing to Prevent Calf
Scours: The Sandhills
Calving System
David R. Smith1
Dale Grotelueschen2
Tim Knott3
Steve Ensley1
1University
of Nebraska–Lincoln
2Pfizer Animal Health
3Sandhills Veterinary Hospital
Calf Scours:
Death loss
Performance loss
Treatment costs
Labor, medication
Human toll
Risk for injury, frustration
Therapy
Replace fluids, electrolytes,
bicarbonate
Treat septicemia
The faith in “cures” and the
practice of dealing with
disease problems only after
they have arisen... is
antagonistic to disease
prevention.
Dr. Leunis Van Es
Lincoln, NE
1932
Does the
“solution”
come in a
bottle?
POPULATION perspective on
preventing infectious disease
Host
Agent
Environment
Infectious disease triad
Host
Agent
Environment
Agents
• Bacteria
– E. coli, Salmonella
• viruses
– rotavirus, coronavirus
• protozoa
– cryptosporidia
• fungi
– mycotic superinfection
Concept #1
Agents of calf scours
• Diarrhea-causing organisms are
widespread in cattle populations
– including herds without scours
problems.
Infectious disease triad
Host
Agent
Environment
Immunity
Exposure
Time
Immunity
Antibodies from
colostrum
Passive
Time
Immunity
Active immune
response
Antibodies from
colostrum
Passive
Time
Acquired
Immunity
Window of vulnerability
Passive
Time
Acquired
Immunity
Window of vulnerability
Scours
Time
Immunity
Exposure
Immunity
Immunity
Scours
0-5
6-10
11-15
Exposure
16-20
Days
21-25
26-30
Concept #2
Age specificity of calf scours
• Calves at highest risk for scours at 1-2
weeks of age
And to begin
Frequency histogram
age of calves at death
shedding
scours agents
Count
25
20
15
10
5
0
5
0
10
6
15
20
25
11
16
21
Age at death (days)
More
26
Immunity
Scours
Time
Exposure
Immunity
Exposure
Time
Immunity
Scours
Time
Exposure
Immunity
SCOURS
Time
Exposure
Level of Exposure
Concept #3
• The level of pathogen exposure is a
function of TIME and:
– ANIMAL DENSITY (crowding -rapid
environmental contamination)
– MULTIPLIER EFFECT
• Cows carry, shed diarrhea-causing
organisms at “low” levels.
• Calves are exposed, shed at “high”
levels, serve as multipliers.
The “multiplier” effect
Count
Frequency of births and deaths by week
120
100
80
60
40
20
0
5/1
5/8
5/2
5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 More
5/9 5/16 5/23 5/30 6/6 6/13 6/20 6/27 7/4
Date
date of birth
deaths
Probability of death
by week of birth
60%
Percent
50%
40%
30%
20%
10%
0%
5/1
5/8
5/2
5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 More
5/9 5/16 5/23 5/30 6/6 6/13 6/20 6/27 7/4
Date
Biosecurity/Pathogen Containment
Host
?
Increase
resistance
Agent
Prevent
effective
contacts
Remove Environment
the agent
X
Biosecurity / Pathogen
Containment
Prevent effective contacts -decrease
the number of contacts that result in
transmission.
•
physical separation: dilution,
segregation, quarantine
•
minimize dose-load: prophylactic
medicines, sanitation
•
minimize contact-time
Prevent
effective
contacts
-decrease the
contacts that result
in transmission.
Ex. calf hutches
Beef
Systems
Can they be
modified to reduce
effective contacts?
Sandhills Calf Scours Project
– Segregate calves
by age to prevent
the multiplier effect
– Move pregnant
cows to new calving
pastures to
minimize dose-load
and contact time
120
100
80
60
40
20
0
5/1
5/8 5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 More
5/2 5/9 5/16 5/23 5/30 6/6 6/13 6/20 6/27 7/4
Date
Probability of death
by week of birth
60%
50%
Percent
• Prevent contacts
Count
Frequency of births
40%
30%
20%
10%
0%
5/1
5/8
5/2
5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 More
5/9 5/16 5/23 5/30 6/6 6/13 6/20 6/27 7/4
Date
Sandhills Calf Scours Project
• Prevent contacts
– Segregate calves
by age to prevent
the multiplier effect
– Move pregnant
cows to new calving
pastures to
minimize dose-load
and contact time
Enough Theory!
Let’s put it
to work...
Sandhills Calving System
Week 1&2
Calving
Pasture
Sandhills Calving System
Week 3
1-2 week old
Pairs
Calving
Pasture
Sandhills Calving System
Week 4
2-3 week old
pairs
1 week old
pairs
Calving
Pasture
Sandhills Calving System
Week 5
2 week old
pairs
1 week old
pairs
Calving
Pasture
Sandhills Calving System
Week 6
Calving
Pasture
2 week old
pairs
1 week old
pairs
Sandhills Calving System
Week 7
Calving
Pasture
1 week old
pairs
2 week old
pairs
Sandhills Calving System
Week 8
Calving
Pasture
1 week old
pairs
2 week old
pairs
Sandhills Calving System
Week 9
Calving
Pasture
-Finish out
1 week old
pairs
2 week old
pairs
Groups commingled after
youngest calf is 4 weeks of age
Case Herd 1
• 800-900 March-calving cows
– paired out from calving lot
• Mortality due to scours
55-120
dead calves
every year
attributed to scours
– 14% 1995
– 6.5% 1996
– 8.2% 1999 (similar losses in ‘97 and ‘98)
• Treatment expenses $3114 /yr (‘95-’99)
Case Herd 1
• Sandhills Calving System in ‘00, ’01, ‘02
• Greatly reduced morbidity and mortality
– 4 calves treated for scours (2000)
– No deaths due to neonatal calf diarrhea
(p<0.01)
• $128.83 /yr in veterinary expenses
– a 24-fold reduction (p<0.01)
Case Herd 1
• Owner estimates the change
was worth $40,000-$50,000 /yr
–greater number of weaned calves
–improved calf performance
–reduced expenses for treatment
Case Herd 2
• 300-400 Summer calving cows
• Intensive grass management
– cattle move through pastures every 2-3 days
• Mortality (1° due to scours)
– 6.5% in 1999
– 11.9% in 2000
Summer calving and
rotating calving pastures
did not prevent
calf scours!
Case Herd 2
• Sandhills Calving System in ‘01-’02
• Modified for intensive grass management
– Split off groups every 100 pairs or 10 days
– multiple groups moving through different
pastures
• Mortality significantly reduced
– “all cause” death loss 2.3% and 1.5% (p<0.01)
– NO deaths from neonatal scours (‘01, 02)
Sandhills Calving System
• Prevent Effective Contacts
to Control Calf Scours
– Move “Heavy” Cows to
Clean Calving Pastures
– Segregate Calves by Age
Sandhills Calving System
• Prevent Effective Contacts
to Control Calf Scours
– Calf Health and Well-Being
– Productivity
– Labor Efficiency
[those concerned with]
food-producing animals
must think in terms of
hygiene, for their
success is in no small
measure dependent
upon their knowledge of
Dr. Leunis Van Es
the subject...
Lincoln, NE
1932
Questions?
David R. Smith DVM, PhD
Extension Veterinarian
402 472-2362
[email protected]