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Management Programs to Optimize Reproduction

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 Costs Cost/cow/cwt $82 $145 $61

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Management Programs to Optimize Reproduction

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  1. Management Programs to Optimize Reproduction GL Stokka DVM,MS Pfizer Animal Health

  2. Quality

  3. 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

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

  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.

  6. Management Decisions that Influence Profitability & Health

  7. Profitability & Health

  8. Profitability & Health

  9. 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

  10. 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

  11. Risk of Disease

  12. Risk of Disease

  13. Vaccinology

  14. 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

  15. IMMUNOLOGY PRINCIPLES • INJECTION = VACCINATION • VACCINATION  IMMUNIZATION • IMMUNIZATION REQUIRES…. • a. Effective vaccine • b. Immunocompetent animal

  16. IMMUNOLOGY PRINCIPLES • for VACCINATION = IMMUNIZATION, requires an IMMUNE RESPONSE • IMMUNE REPONSE • cognition • activation • effect

  17. 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.

  18. 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

  19. IMMUNOLOGY PRINCIPLES Because of IMMUNOLOGIC MEMORY multiple doses of vaccine SHORTEN THE TIME & RAISE THE IMMUNITY LEVEL AND INCREASE THE NUMBER OF IMMUNE ANIMALS

  20. Challenge Level High challenge No or low challenge Before Vaccination After Vaccination Susceptible Non-Susceptible With PI

  21. 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.

  22. 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.

  23. 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.

  24. 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.

  25. 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.

  26. IMMUNOLOGY PRINCIPLES • PREEXPOSURE IMMUNIZATION • “REALISTIC EXPECTATIONS” • 1. Will rarely make disease rate = zero • 2. If disease rate is low, hard to see effect

  27. IMMUNOLOGY PRINCIPLES • Challenge Dose • Even a normally protective level of immunity can be overwhelmed…

  28. IMMUNOLOGY PRINCIPLES • IMMUNIZATION REQUIRES…. • a. Effective vaccine • b. Immunocompetent animal

  29. VACCINE MANAGEMENT FACTORS: • Vaccine Handling • Temperature abuse • Ultraviolet light (sunlight) • Disinfectants

  30. Fetal Protection

  31. Fetal Protection • IBR • BVD • Lepto • Vibrio • Trichomoniasis • Neopsora

  32. 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)

  33. Routes of Persistent Infection Non-immune pregnant cow exposed to NCP BVDV Persistently Infected calf Persistently infected cow giving birth

  34. 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

  35. 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

  36. Fetal protection claims for BVDV Vaccines

  37. 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

  38. 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

  39. 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.

  40. 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

  41. 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

  42. Safety for Administering MLV to Calves Nursing Previously Vaccinated Pregnant Cows

  43. 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

  44. 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: StudyControls (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 Trimester99.3% (148 / 149)99.5% (195 / 196) Total97.8%(634 / 648) 97.7% (679 / 695)

  45. 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.

  46. Summary

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