Management Programs to Optimize Reproduction

Management Programs to Management Programs to Optimize ReproductionOptimize Reproduction

Management Programs to Management Programs to Optimize ReproductionOptimize Reproduction

GL Stokka DVM,MS Pfizer Animal Health

QualityQualityQualityQuality

Cow Production & CostsCow Production & CostsMedium 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

Health CostsHealth CostsHealth CostsHealth Costs

Health Costs as % of total maintenance cost of a beef cow.

$15.00 to $25.00 (3.5% to 5%)

Cost of Production TargetsCost of Production TargetsCost of Production TargetsCost 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 Management Decisions that Influence Profitability & Health Influence Profitability & Health

Profitability Profitability & Health& Health

Profitability Profitability & Health& Health

Profitability & HealthProfitability & HealthProfitability & HealthProfitability & Health

Failure of passive transfer Failure of passive transfer (FPT)(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 Health and performance effects of inadequate colostral transfer in beef inadequate colostral transfer in beef

calvescalves

Health and performance effects of Health and performance effects of inadequate colostral transfer in beef inadequate colostral transfer in beef

calvescalves 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 DiseaseRisk of DiseaseRisk of DiseaseRisk of Disease

Risk of Disease Risk of Disease Risk of Disease Risk of Disease

VaccinologyVaccinologyVaccinologyVaccinology

What is a What is a VaccineVaccine????What is a What is a VaccineVaccine????

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

• INJECTION = VACCINATION

• VACCINATION IMMUNIZATION

• IMMUNIZATION REQUIRES…. a. Effective vaccineb. Immunocompetent animal

IMMUNOLOGY PRINCIPLES

• for VACCINATION = IMMUNIZATION, requires an IMMUNE RESPONSE

• IMMUNE REPONSE•cognition•activation•effect


• mounting an immune response is complicated & TAKES TIMETAKES TIME

• Immune response takes 3 to 10 days or longer to kick in. Longer with naive animals.

• Peaks in 2 to 4 weeks.


•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

Incubation and ProtectionIncubation and ProtectionIncubation and ProtectionIncubation and Protection

Because of

IMMUNOLOGIC MEMORY multiple doses of vaccine SHORTEN THE TIME & RAISE THE IMMUNITY LEVEL

AND INCREASE THE NUMBER OF IMMUNE ANIMALS


Population Dynamics

Relative Level of Resistance

Nu

mb

er o

f A

nim

als

Challenge Level

Susceptible Non-Susceptible

Before Vaccination After Vaccination

With PI

No or low challenge High challenge

Individual VaccinationIndividual VaccinationIndividual VaccinationIndividual 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 ImmunityHerd ImmunityHerd ImmunityHerd 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)Reproductive Rate(R)Reproductive Rate(R)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 RateReproductive RateReproductive RateReproductive 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 ImmunityHerd ImmunityHerd ImmunityHerd 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.

• PREEXPOSURE IMMUNIZATION “REALISTIC EXPECTATIONS”

1. Will rarely make disease rate = zero

2. If disease rate is low, hard to see effect


Challenge Dose

• Even a normally protective level of immunity can be overwhelmed…


•IMMUNIZATION REQUIRES….

a. Effective vaccine

b. Immunocompetent animal


Vaccine Handling

• Temperature abuse

• Ultraviolet light (sunlight)

• Disinfectants

VACCINE MANAGEMENT FACTORS:

Fetal ProtectionFetal ProtectionFetal ProtectionFetal Protection

Fetal ProtectionFetal ProtectionFetal ProtectionFetal Protection

IBR BVD Lepto Vibrio Trichomoniasis Neopsora

Vaccinations for Fetal ProtectionOverview•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 Persistently infected cow infected cow giving birthgiving birth

Persistently Persistently Infected calfInfected calf

BVD TransmissionBVD TransmissionBVD TransmissionBVD 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

Risk of transmissionRisk of transmissionRisk of transmissionRisk 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 Fetal protection claims for BVDV VaccinesBVDV Vaccines

Fetal protection claims for Fetal protection claims for BVDV VaccinesBVDV Vaccines

Failure of foetal protection after Failure of foetal protection after vaccination against an experimental vaccination against an experimental

infection with bovine virus diarrhea virusinfection with bovine virus diarrhea virus


infection with bovine virus diarrhea virusinfection 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





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 Foetal cross-protection experiments between type I and type II bovine between type I and type II bovine diarrhoea virus in pregnant ewesdiarrhoea virus in pregnant ewes

Foetal cross-protection experiments Foetal cross-protection experiments between type I and type II bovine between type I and type II bovine diarrhoea virus in pregnant ewesdiarrhoea 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 Modified live type bovine viral diarrhea virus (BVDV) provides fetal protection virus (BVDV) provides fetal protection against challenge with a type 1 & 2 against challenge with a type 1 & 2 BVDVBVDVType 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 PINo difference between single or two doses

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 PINo difference between one and two doses

Modified live type bovine viral diarrhea Modified live type bovine viral diarrhea virus (BVDV) provides fetal protection virus (BVDV) provides fetal protection against challenge with a type 1 & 2 against challenge with a type 1 & 2 BVDVBVDV

Safety for Administering MLV Safety for Administering MLV to Calves Nursing Previously to Calves Nursing Previously Vaccinated Pregnant CowsVaccinated Pregnant Cows

Safety for Administering MLV Safety for Administering MLV to Calves Nursing Previously to Calves Nursing Previously Vaccinated Pregnant CowsVaccinated Pregnant Cows

Safety for Administering MLV to Safety for Administering MLV to Calves Nursing Previously Calves Nursing Previously Vaccinated Pregnant CowsVaccinated Pregnant Cows


Field Safety Studies in1rst, 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



Field Safety Studies in1rst, 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)

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.

SummarySummarySummarySummary

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Management Programs to Optimize Reproduction