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Management Programs to
Optimize Reproduction
GL Stokka DVM,MS Pfizer Animal Health
Quality
Cow Production & Costs
Medium
Low
High
% Calves weaned
87
83
90
% Calf death loss
3.4
2.9
2.4
wean wt/cow exposed
455
413
455
Cost/cow/cwt
$82
$145
$61
Health costs/cwt
$4(5%)
$6(4%)
$3.50(6)
Calf breakeven/lb
$0.69
$1.36
$0.41
ROA
2.88
-15.55
18.16
•SPA Northern herds
•Barry Dunn SDSU
Costs
Health Costs
Health Costs as % of total
maintenance cost of a beef cow.
 $15.00 to $25.00 (3.5% to 5%)

Cost of Production Targets
$0.60/lb cost of producing a weaned
calf.
 Health program costs 5% - $0.03/lb.
 One dollar difference/head
assuming health costs at $20/hd.
5% of $0.03 = $.0015.

Management Decisions that
Influence Profitability & Health
Profitability
& Health
Profitability & Health
Failure of passive transfer
(FPT)
Calves with inadequate
immunoglobulin concentrations at
24 hours of age were 3.2-9.5 times
more likely to become sick and 5.4
times more likely to die prior to
weaning.
 Levels <800mg of IgG/dl are
considered inadequate.

Wittum
TE, Perino LJ AJVR Sep. 1995
Health and performance effects of
inadequate colostral transfer in beef
calves



Lower perinatal IgG1 levels were significantly
associated with higher morbidity, higher mortality
and lower gain in the preweaning period. (p<=0.5)
Calves with serum IgG1 levels up to 2500 mg/dl
were 1.5X more likely to get sick before weaning
and 2.4X more likely to die before weaning than
calves with higher IgG1 levels.
Calves with IgG1 levels of at least 2700 mg/dl
weighed 7.38 pounds more at 205 days of age than
calves with lower IgG1 levels.
– Dewell, RD., Hungerford, LL., Keen, JE., Grotelueschen,
DM., Rupp, GP., Griffin, DD., 2002 Proceedings AABP
Risk of Disease
Risk of Disease
Vaccinology
What is a Vaccine??


Contains material originating from the
disease causing “bug” that can induce
resistance (immunity) to disease.
Vaccines work by stimulating the body to
produce:
Antibodies
Killer Cells
Memory Cells
IMMUNOLOGY PRINCIPLES
• INJECTION = VACCINATION
• VACCINATION  IMMUNIZATION
• IMMUNIZATION REQUIRES….
a. Effective vaccine
b. Immunocompetent animal
IMMUNOLOGY PRINCIPLES
• for VACCINATION = IMMUNIZATION,
requires an IMMUNE RESPONSE
• IMMUNE REPONSE
•cognition
•activation
•effect
IMMUNOLOGY PRINCIPLES
• mounting an immune response is
complicated & TAKES TIME
• Immune response takes 3 to 10 days or
longer to kick in. Longer with naive
animals.
• Peaks in 2 to 4 weeks.
Incubation and Protection
•IBR – 3 days, protection 40 to 96 hours.
•BVD – 5 days, protection 21 days +.
•M. hemolytica – 7 to 10 days, protection
14 days.
•Mycoplasma – 12 days, protection 14
days (doses?).
•BRSV – 5 days, protection 11 days.
•RBCV - ??
•Multiple references
IMMUNOLOGY PRINCIPLES
Because of
IMMUNOLOGIC MEMORY
multiple doses of vaccine
SHORTEN THE TIME &
RAISE THE IMMUNITY LEVEL
AND INCREASE
THE NUMBER OF
IMMUNE ANIMALS
Population Dynamics
Challenge Level
Number of Animals
No or low challenge
Before Vaccination
High challenge
After Vaccination
Susceptible
Non-Susceptible
Relative Level of Resistance
With PI
Individual Vaccination



Induces protection against disease, i.e.
clinical signs.
Reduce susceptibility of an individual
against infection, infectious dose
needed to establish infection is higher
after vaccination.
Reduces infectivity after the occurrence
of an infection.
Herd Immunity



Reduced probability of an individual
becoming infected when it is part of a
vaccinated population.
Chance of becoming infected in a
population decreases with increasing
density of individuals being vaccinated.
Prevent transmission of pathogen within
the population to such an extent that the
infection will eventually be controlled or
become extinct.
•
Potgieter L., Immunology of Bovine Virus Diarrhea Virus.
November 1995 VCNA Vol 11 No 3 pp 501-520.
Reproductive Rate(R)


The spread of disease depends on the
reproductive rate (R, how many new cases arise
on average from one infectious animal) of an
infectious disease agent.
In general at the herd level, the basic reproductive
rate of the disease in vaccinated populations
should be below 1 to prevent the spread of
infection.
Reproductive Rate

The higher the R the greater the number of animals that
must be immune in order to prevent spread of the
infectious agent. If R in a vaccinated population is larger
than one, then the vaccine cannot totally prevent the
spread of infection and other biosecurity principles must
be employed.
– Noordhuizen, JPTM, Frankena, K, C.M. van der Hoofd, E.A.M. Graat,
in Application of Quantitative Methods in Veterinary Epidemiology
Wageningen Pers, Wageningen, Netherlands 1997 pp249-269.
– Hage, et al Vet Micro 53 (1996) 169-180.
Herd Immunity





Immunization for herd immunity against BVDV
need be 57% in herds without PI’s.
97% with PI’s based on mathematical models.
For IBR at least 86% of population must be
immune to reduce Ro to less than 1.
For PRV Ro = 10. After vaccination 0.5.
For Mannheimia? 12 marker calves spread to 10
others.
–
–
–
–
Cherry BR et al Prev Vet Med 1998
Hage, et al Vet Micro 53 (1996) 169-180.
De Jong, Kimman Vaccine 1994 761-766.
Briggs, et al Am J Vet Res 1998 59:401-405.
IMMUNOLOGY PRINCIPLES
• PREEXPOSURE IMMUNIZATION
“REALISTIC EXPECTATIONS”
1. Will rarely make disease rate = zero
2. If disease rate is low, hard to see effect
IMMUNOLOGY PRINCIPLES
Challenge Dose
• Even a normally protective level of
immunity can be overwhelmed…
IMMUNOLOGY PRINCIPLES
•IMMUNIZATION REQUIRES….
a. Effective vaccine
b. Immunocompetent animal
VACCINE MANAGEMENT FACTORS:
Vaccine Handling
• Temperature abuse
• Ultraviolet light (sunlight)
• Disinfectants
Fetal Protection
Fetal Protection
IBR
 BVD
 Lepto
 Vibrio
 Trichomoniasis
 Neopsora

Vaccinations for Fetal Protection
Overview
•The anatomy of the bovine cow-fetal connection
(multilayered placenta) precludes antibodies and
other immune cells from crossing the placenta and
providing protection for the developing fetus
•Thus the developing bovine fetus is susceptible to
small amounts of infectious agents (less than
1000 viral particles)
Routes of Persistent Infection
Non-immune
pregnant cow exposed
to NCP BVDV
Persistently
Infected calf
Persistently
infected cow
giving birth
BVD Transmission



PI animals shed large amounts of virus.
Excreted in smaller amounts from
acutely infected animals for only a few
days.
Direct contact with PI most efficient
mode.
– One hour of direct contact allowing nose-tonose contact was sufficient for transmission.
– Direct contact with acutely infected can
transmit though less efficiently.
Houe, Vet Microbiology 1999
Risk of transmission

Between Herds
– Most commonly by PI animals
introduced to herds.
– If prevalence is 2%, risk of purchasing
PI animal in a group of 20 is 33%.
– P = 1- probability of buying non PI
animal. P = 1 – 0.98n n = number of
animals purchased.
Houe, Vet Microbiology 1999
Fetal protection claims for
BVDV Vaccines
Failure of foetal protection after
vaccination against an experimental
infection with bovine virus diarrhea virus
 Two inactivated BVDV vaccines were applied twice

within a 3 week interval. Challenge virus was
applied 5 months after completion of the
vaccination protocol.
All calves born from unvaccinates were born PI.
Six out of 9 calves were born PI with 1 calf having
pre-colostral antibodies from vaccine A. Eight out
of 15 calves were born PI with 2 calves having precolostral antibodies from vaccine B.

Zimmer, GM., Wentink GH., Bruschke, FJ., Westenbrink, J., Brinkhof, J., de
Goey, I. Vet Micro 2002 Vol 89(4);255-265
Failure of foetal protection after
vaccination against an experimental
infection with bovine virus diarrhea virus
 No relation between virus isolation from blood and


birth of PI calves.
No relation between titers after vaccination, on
day of challenge and birth of PI calves.
Challenge model must allow enough time for fetal
infection to occur, in this study several calves
born with active immunity indicating fetal infection
occurred at least 1 month after challenge.
Infection may have been delayed by immune
response of the vaccination.

Zimmer, GM., Wentink GH., Bruschke, FJ., Westenbrink, J., Brinkhof, J., de
Goey, I. Vet Micro 2002 Vol 89(4);255-265
Foetal cross-protection experiments
between type I and type II bovine
diarrhoea virus in pregnant ewes



Fetuses from ewes immunized with BVDV-1 were
protected when challenged with BVDV-2.
All fetuses were infected from ewes immunized
with BVDV-2 and challenged with BVDV-1.
Pre-challenge level of neutralizing antibody is not
a reliable indicator of fetal protection.
• Paton, DJ., Sharp, G., Ibata, G., Vet Micro 1999 64;
185-196.
Modified live type bovine viral diarrhea
virus (BVDV) provides fetal protection
against challenge with a type 1 & 2
BVDV
Type 1 Challenge
•One And two doses of NADL vaccine
(PregGuard and Bovi-Shield)
•Challenge with 104.8 TCID 50 doses of
noncytopathic Type 1 BVD strain 816317,
administered IN, New York isolate calves taken
to term
1/38 vaccinates had a PI calf
7/10 control calves born PI
No difference between single or two doses
Modified live type bovine viral diarrhea
virus (BVDV) provides fetal protection
against challenge with a type 1 & 2
BVDV
Type 2 Challenge
•One And two doses of NADL vaccine
(PregGuard and Bovi-Shield)
•Challenged with 1 X 103.9 TCID 50 doses of
noncytopathic BVD Type 2 virus strain 94B5359a, administered IN, Wyoming isolate
calves taken to term
13/37 vaccinates had a PI calf
9/10 control calves born PI
No difference between one and two doses
Safety for Administering MLV
to Calves Nursing Previously
Vaccinated Pregnant Cows
Safety for Administering MLV to
Calves Nursing Previously
Vaccinated Pregnant Cows
Field Safety Studies in
1rst, 2nd, and 3rd Trimester Pregnant Animals

Study Animals and Sites:
• 1rst trimester pregnant beef cows in Leith, North Dakota
• 2nd trimester pregnant holstein heifers in Hanford,
California
• 3rd trimester pregnant beef cows in Medicine Lodge,
Kansas
Safety for Administering MLV to
Calves Nursing Previously
Vaccinated Pregnant Cows
Field Safety Studies in
1rst, 2nd, and 3rd Trimester Pregnant Animals
 Normal
Study
Calving Rates:
Controls (T1)
Vaccinates (T2 – T4)
1rst Trimester
99.2% (261 / 263)
99.6% (263 / 264)
2nd Trimester
95.3% (225 / 236)
93.6% (220 / 235)
3rd Trimester
99.3% (148 / 149)
99.5% (195 / 196)
Total
97.8% (634 / 648)
97.7% (679 / 695)
Vaccines & Fetal Protection
•Complete reproductive
protection(BVDV) can not be obtained
from vaccination. IBR protection seems
strong
•Do not over promise what vaccination
can do.
•Incorporate vaccination with the other
control measures.
•Biosecurity & testing.
Summary