BRD Prevention and Control

Question 1

OBJ: Describe vaccines and expected response (Killed vs modified live; viral / bacterial)

Question 2

OBJ: Know vaccine use and expected efficacy for BRD

Question 3

OBJ: Understand value of preconditioning

Question 4

OBJ: Understand when metaphylaxis would be used and expectations for iimpact

Question 5

What is the difference between vaccination, immunization, and protection?

Answer 5

• Vaccination - act of admnistering the vaccine
• Immunization - when the animal mounts an appropriate response to the vaccine
• Protection - when the animals immunity is greater than the challenge

Question 6

What is Herd Immunity

Answer 6

The % of a herd that must be immune to stop transmission

• 86% for IBR
• 57-97% for BVD

Question 7

What are the different classes of vaccines? how are they different?

Answer 7

• Killed (inactivated)
  
  • Stable
  • More expensive
  • has adjuvant
  • Labled for suckling calves
  • Require a booster
• Modified-Live (attenuated)
  
  • Rapid, long lasting protection
  • Modified replication of virus
  • Restricted use in suckling calves and pregnant cows

Question 8

What are the different responses to a vaccine?

Answer 8

• Response based on Antigen type, route of administration, and type of vaccine
• Local response:
  
  • Immunoglobulins, IgA, Interferons
  • Fast response
  • Focused locally
• Humoral Response:
  
  • B-lymphocytes, antibodies
  • More stimulation killed vaccine
• Cell-mediated Response:
  
  • T-lymphocytes, Memory T-cells
  • More stimulation modified live vaccine

Question 9

How should vaccines be handles?

Answer 9

• Follow label
  
  • expiration, withdrawal
  • Route of administration
• Controlled environment
  
  • Temperature
  • sunlight exposure
• Combination
  
  • No mixing vaccines
  • Injection site spacing
• MLV reconstitution
  
  • Limited lifespan after mixed
• Cleanliness
  
  • Needles, syringes
  • Avoid disinfectants with MLV

Question 10

How often do feedyards vaccinate cattle on arrival?

Answer 10

Question 11

What are the challenges for evaluating BRD vaccine efficacy?

Answer 11

• Multi-factoral nature of BRD
• Variability among pens/cohorts
• Confounding with origin/other
• Complexity of response to BRD pathogens

Question 12

What is Vaccination cost effectiveness based on?

Answer 12

• Vaccine Cost (VC)
  
  • cost of vaccine and labor
• Disease Incidence (DI)
  
  • expected incidence of disease trying to prevent in population
• Disease Cost (DC)
  
  • average cost of morbidity and mortality
• Vaccine Efficacy (VE)
  
  • expected reduction in incidence and severity

Cost effective if:

VC < (DI x DC x VE)

Question 13

What is Preconditioning?

Answer 13

• Preparing calves for the next production phase
• Goals of Preconditioning:
  
  • Build immunity prior to exposure
  • Minimize stress associated with phase transition
  • Ease dietary transition to next phase
• Management procedures:
  
  • Immunizations
  • Deworming
  • Castration
  • Weaning
  • Nutrition
  • Biosecurity

Question 14

What are the different types of Preconditioning programs?

Answer 14

• One or two vaccinations, No weaning (Pre- Wean program)
  
  • Initial processing (3-4 wks prior to weaning)
    
    • IBR/BVD/BRSV/PI3 vaccine
    • Clostridial vaccine
    • Castration
    • +/- mannheimia vaccine
  • Second Processing (at weaning)
    
    • IVR/BVD/BRSV/PI3 vaccine
    • Clostridial vaccine
    • Deworming
  • Sale > 30-45d post weaning
• Two vaccinations, weaning (Weaning Program)
  
  • Initial processing (at weaning)
    
    • IBR/BVD/BRSV/PI3 vaccine
    • Clostridial vaccine
    • Castration
    • Deworming
  • Second processing (3-4 weeks post weaning
    
    • IBR/BVD/BRSV/PI3 vaccine
    • Clostridial vaccine
    • +/- Mannheimia vaccine
  • Sale > 30d post second processing

Question 15

How does the timing of castration and dehorning affect cattle?

Answer 15

• Prior to arrival:
  
  • More frequent feeding
  • Greater ADG improved gain:feed
  • Reduced BRD risk
• At arriaval:
  
  • Prolongs starting period
  • Delayed procedures reduces ADG
  • Increased (1-3x) BRD risk

Question 16

What are the different weaning methods for cattle? Pros/Cons?

Answer 16

• Confined/Abrupt weaning:
  
  • Pros - find feed, water; less labor
  • Cons - Disease concentration, Environment, abrupt = higher stress
    
    • more cortisol, more vocalization, short term weight loss
• Low Stress weaning:
  
  • “Fenceline weaning” “2-stage weaning” (includes anti-suckling device
  • Pros- low stress (less vocalization, less walking)
  • Cons: facility/labour requirements

Question 17

What is metaphylaxis? Why is it popular? what are the indications for its use?

Answer 17

• Treatment of entire group with approved antimicrobial to control acute onset of BRD
  
  • Oral/injectable
• Used influenced by the inability to identify subclinical illness in populations
• Indications for use:
  
  • Cattle at high risk for BRD
    
    • commingles
    • transported
    • castration
    • season/weather
    • vaccination history
    • clinical disease

Question 18

What is the difference between metaphylaxis and prophylaxis?

Answer 18

• Met = treatment on arrival
• Pro = treatment during outbreak
  
  • based on number/% of cases over a defined time period

Question 19

What antimicrobials are approved for metaphylactic use in the US

Answer 19

Question 20

What are the effects of metaphylaxis on BRD?

Answer 20

• Reduced animal health challenge:
  
  • Reduce morbidity by ~50%
  • Reduced mortality by ~50%
• Improved performance (ADG)
• Improvement varies by class of antimicrobials and disease challenge

Question 21

What affects the decision to give metaphylaxis treatment?

Answer 21

• Guidelines:
  
  • Clinical appearance at arrival
  • current and expected morbidity / morality patterns
  • Feed consumption
  • Elevated body temperatures
  • Expected efficacy of products
• Factors influencing economic viability
  
  • Cost of product
  • Expected disease reduction
  • Cost of disease
  • Expected level of diease