David R' Smith, DVM, PhD

1
Applying population thinking to neonatal calf
diarrhea
An introduction to the principles of the
Sandhills Calving System

• David R. Smith, DVM, PhD
• University of NebraskaLincoln

2
Veterinarians Oath
I solemnly swear to use my scientific knowledge
and skills for the benefit of society through the
protection of animal health, the relief of animal
suffering, the conservation of animal
resources, the promotion of public health, and
the advancement of medical knowledge
AVMA, 1999
3
Undifferentiated neonatal calf diarrhea Death
loss Performance loss Treatment costs
Labor, medication Human toll Risk for
injury, frustration
4
Undifferentiated neonatal calf diarrheaPublic
Health Concerns Zoonoses Salmonella
Cryptosporidia Antibiotic usage
5
Sandhills Calving System reduces scours
Successful Farming John Walter and Betsy Freese
Jan 25, 2006

• In about an hour, Terry Clements finishes a
  chore that has helped cut calf scours on his Loup
  County, Nebraska, ranch to nonexistent

6
The Principles of Animal Hygiene and Preventive
Veterinary Medicine

• The faith in cures and the practice of
  dealing with disease problems only after they
  have arisen, which thousands of years of magic
  and dosing have firmly establishedis
  antagonistic to disease prevention
• Leunis Van Es
• Lincoln, NE 1932

7
Great advances in medicine
Kochs postulates of infectious disease causation
Flemings discovery of penicillin
Pasteurs pioneering work in germ theory and
immunology
8
Great advances in medicine
Hippocrates 400 BC On Airs, Waters, and Places
Dr. John Snows pioneering work in modern
epidemiology
9
John Snow, London cholera epidemic,1854
remove the handle from the Broad St. pump
10
The McLean County System of Swine Sanitation

• Management system to control internal parasites
  of young pigs
• Based on farrowing hygiene and movement of sow
  and pigs to clean pastures
• Tested 1919-1926
• Reviewed- 1942 USDA Yearbook of Agriculture.
  pp774-780

A
A. These large, healthy pigs were protected
from the ravages of parasites B. These unthrifty
pigs became parasitized soon after they
were born
B
11
Nebraska Field Disease Research Diagnostic
investigation Field epidemiology Case-studies of
interventions
12
Agents

• bacteria
• E. coli, Salmonella
• viruses
• rotavirus, coronavirus
• protozoa
• cryptosporidia
• fungi
• mycotic superinfection

13
Agents of calf scours

• Diarrhea-causing organisms are common in cattle
  populations
• including herds without scours problems.

bovine coronavirus
cryptosporidia
14
(No Transcript)
15
The battle between exposure and immunity begins
at birth
16
Immunity
Antibodies from colostrum
Age
Passive
17
Immunity
Active immune response
Antibodies from colostrum
Age
Passive
Acquired
18
Immunity
Window of vulnerability
Age
Passive
Acquired
19
Immunity
Window of vulnerability
Scours
Exposure
Age
20
Immunity
Scours
Exposure
0-5 6-10 11-15 16-20 21-25
26-30
Age in Days
21
Age specificity of calf scours

• Population susceptible to scours calves 1-3
  weeks of age

Also when calves become infective
22
Nebraska Sandhills
23
The Nebraska Sandhills consists of 19,600 square
miles of sand-dune formation covered by native
grassland.
24
Nebraska Sandhills
25
Arthur County, NE402 people/718 sq. mile (2004
est)29,705 cattle and calves (2002 USDA)
26
Beef herd experiencing severe losses to calf
scours

• 402 cattle with live births, managed as a single
  group intensive grazing
• No treatment or control interventions
• 48 deaths due to scours
• An epidemiologically-pure scours epidemic
• and RECORDS!

27
(No Transcript)
28
(No Transcript)
29
Factors of the calf explaining death from scours

30
Factors of the calf explaining death from scours

• Calves born on the day of a pasture-move were
  more likely to die (OR1.9, p0.09)

31
Age of the calf at death
32
Age of death over time
Death in the same age-range throughout the
calving season
33
Size of the at-risk population
34
Weekly rates of mortality
Force of disease
neonatal diarrhea deaths / at-risk
35
Proportion of the calves born each week that
eventually died from neonatal diarrhea
36

• Levels of pathogen exposure increase over TIME
  within a calving season

• Increasing ANIMAL DENSITY (more effective
  contacts and environmental contamination)
• MULTIPLIER EFFECT
• Cows - low level shedders
• Calves multiply pathogens to higher and higher
  levels resulting in greater infectivity

37
Multiplier Effect
38
Biocontainment strategies for neonatal calf
diarrhea

• Eliminate the agent and keep it out
• Increase host resistance
• Colostrum!
• Prevent effective contacts older infective
  calves and contaminated environment!

39
Sandhills Calf Scours Project
Frequency of births
120
100
80

• Re-create the conditions existing at the start
  of the calving season
• Clean calving area
• Absence of older calves as a source of exposure

60
Count
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
40
Sandhills Calf Scours Project
Frequency of births
120

• Re-create the conditions at the start of the
  calving season
• Move pregnant cows to new calving pastures each
  week
• Minimize dose-load
• Improve maternal bonding
• Segregate calves by age to prevent the multiplier
  effect

100
80
60
Count
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
41
Sandhills Calving SystemWeek 12
Calving Pasture
42
Sandhills Calving System Week 3
Calving Pasture
1-2 week old Pairs
43
Sandhills Calving System Week 4
1 week old pairs
Calving Pasture
2-3 week old pairs
44
Sandhills Calving System Week 5
2 week old pairs
1 week old pairs
Calving Pasture
45
Sandhills Calving System Week 6
Calving Pasture
2 week old pairs
1 week old pairs
46
Sandhills Calving System Week 7
Calving Pasture
1 week old pairs
2 week old pairs
47
Sandhills Calving System Week 8
Calving Pasture
1 week old pairs
2 week old pairs
48
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
49
Develop a plan
50

• Less death and illness due to neonatal scours
  (plt0.01)
• Minimal to no treatment or antibiotic use
• 24-fold reduction in animal health expenses
  (plt0.01)

51
Sandhills Calving System reduces scours
Successful Farming John Walter and Betsy Freese
Jan 25, 2006

• "This is the number one thing I've done over the
  years that has benefited us economically,"
  Clements says.

52
Veterinarians Oath
the protection of animal health, the relief of
animal suffering, the conservation of animal
resources, the promotion of public health

53
The Principles of Animal Hygiene and Preventive
Veterinary Medicine

• those more particularly concerned with the
  food-producing animals must think in terms of
  hygiene, for their success is in no small measure
  dependent upon their knowledge of the subject
• Leunis Van Es Lincoln, NE 1932

54
Population Thinking Series
1110 AM
145 PM
1010 AM
435 PM
415 PM
245 PM
NAVC -Monday, January 19, 2009
55
http//vetext.unl.edu/ Search for sandhills
calving system