Management Programs to Optimize Reproduction

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Management Programs to Optimize Reproduction
GL Stokka DVM,MS Pfizer Animal Health
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Quality
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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 Costs 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

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Health Costs

• Health Costs as of total maintenance cost of a
  beef cow.
• 15.00 to 25.00 (3.5 to 5)

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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.

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Management Decisions that Influence Profitability
Health
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Profitability Health
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Profitability Health
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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 lt800mg of IgG/dl are considered inadequate.

• Wittum TE, Perino LJ AJVR Sep. 1995

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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. (plt0.5)
• 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

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Risk of Disease
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Risk of Disease
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Vaccinology
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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

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IMMUNOLOGY PRINCIPLES

• INJECTION VACCINATION
• VACCINATION ? IMMUNIZATION
• IMMUNIZATION REQUIRES.
• a. Effective vaccine
• b. Immunocompetent animal

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IMMUNOLOGY PRINCIPLES

• for VACCINATION IMMUNIZATION, requires an
  IMMUNE RESPONSE
• IMMUNE REPONSE
• cognition
• activation
• effect

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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.

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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

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IMMUNOLOGY PRINCIPLES
Because of IMMUNOLOGIC MEMORY multiple doses
of vaccine SHORTEN THE TIME RAISE THE
IMMUNITY LEVEL AND INCREASE THE NUMBER OF
IMMUNE ANIMALS
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Challenge Level
High challenge
No or low challenge
Before Vaccination
After Vaccination
Susceptible
Non-Susceptible
With PI
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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.

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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.
  

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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.

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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.

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Herd Immunity

• Immunization for herd immunity against BVDV need
  be 57 in herds without PIs.
• 97 with PIs 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 59401-405.

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IMMUNOLOGY PRINCIPLES

• PREEXPOSURE IMMUNIZATION
• REALISTIC EXPECTATIONS
• 1. Will rarely make disease rate zero
• 2. If disease rate is low, hard to see effect

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IMMUNOLOGY PRINCIPLES

• Challenge Dose
• Even a normally protective level of immunity can
  be overwhelmed

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IMMUNOLOGY PRINCIPLES

• IMMUNIZATION REQUIRES.
• a. Effective vaccine
• b. Immunocompetent animal

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VACCINE MANAGEMENT FACTORS

• Vaccine Handling
• Temperature abuse
• Ultraviolet light (sunlight)
• Disinfectants

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Fetal Protection
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Fetal Protection

• IBR
• BVD
• Lepto
• Vibrio
• Trichomoniasis
• Neopsora

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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)

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Routes of Persistent Infection
Non-immune pregnant cow exposed to NCP BVDV
Persistently Infected calf
Persistently infected cow giving birth
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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-to-nose
  contact was sufficient for transmission.
• Direct contact with acutely infected can transmit
  though less efficiently.

Houe, Vet Microbiology 1999
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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
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Fetal protection claims for BVDV Vaccines
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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 pre-colostral 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

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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

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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.

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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

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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 94B-5359a,
  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

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Safety for Administering MLV to Calves Nursing
Previously Vaccinated Pregnant Cows
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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

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Safety for Administering MLV to Calves Nursing
Previously Vaccinated Pregnant Cows

• Field Safety Studies in
• 1rst, 2nd, and 3rd Trimester Pregnant Animals
• Normal Calving Rates
• Study 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)

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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.

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Summary