Herd health investigation 4

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Herd health investigation 4

• Mark Stevenson
• EpiCentre, IVABS, Massey University, Palmerston
  North
• M.Stevenson_at_massey.ac.nz

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Herd health

• What this series of lectures will cover
• Lecture 1
• multifactorial nature of disease
• investigating problems and implementing
  interventions
• Lectures 2 and 3
• causation
• measures of health
• Lecure 4
• case studies
• tools for herd health investigations

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Case study 2

• Background
• 250 cow autumn-calving dairy herd in the Manawatu
• reproductive performance in this herd usually
  good
• Planned Start of Calving 10 March
• Planned Start of Mating 1 June
• on 1 December, youve pregnancy tested the herd
  and estimate
• 8 week in-calf rate 75 (target gt 90)
• 18 of the herd empty

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Case study 2

• Do we have a problem?
• When did the problem start?
• Define the problem more specifically

YES!
THIS SEASON
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Case study 2

• What is the problem?
• high number of empty cows identified at pregnancy
  test
• Is there a true excess of disease?
• calving pattern OK
• submission rates OK
• return intervals OK
• conception rates depressed (actual 37, target gt
  60)

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Case study 2

• Establish a case definition
• reduced herd fertility due to failure to conceive
  to service
• Enhance surveillance
• not of immediate importance at this time, since
  mating completed

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Case study 2

• Describe problem in terms of animal, place and
  time
• involves a (reasonably) detailed reproductive
  analysis
• what are some of the common risks for failure to
  conceive?
• age, type of service (AI vs natural), sire, time
  of mating, health disorders, days calved at
  mating start
• Generate and test hypotheses

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Case study 2

• Factors influencing conception rate in this herd
• sires
• week of mating
• health
• days calved at time of mating

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Case study 2

• Recommendations for the future
• sires ? ?
• week of mating ? attention to staffing during
  Field Days
• health ? ? post partum vet checks
• days calved at time of mating ? attention to
  calving pattern

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Case study 2

• First law of herd health
• identifying a cause of failure is rarely
  critical ensuring that failure does not occur in
  future is critical
• Second law of herd health
• suboptimal performance in a herd is usually the
  result of small failures in multiple areas
• this contrasts with individual animal medicine,
  where we tend to associate many clinical signs
  with a single pathological process

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Case study 2

• Compare performance with established targets
• Identify those animals at risk of failure
• Once risks have been identified manage them
• Monitor responses
• if it aint measured it aint busted

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Roadmap

• Case study 2
• Tools for herd health investigations

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Tools for herd health investigations

• Herd managers need systems to record details
  about animals within a herd and events that
  happen to those animals over their lifetime
• Options
• wall charts
• paper systems
• computerised records

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Tools for herd health investigations

• A good system will provide
• individual animal details
• lists of day-to-day tasks
• reports that help guide strategic management
• identify shortfalls in farm-herd performance
• establish optimal system of production
• a means for satisfying regulatory requirements

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Individual animal details
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Day-to-day tasks
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Reports
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Regulatory
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Palm held devices
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Tools for herd health investigations

• Other tools
• ration evaluation software
• are the cows getting the nutrients they need for
  a given stage of lactation and level of
  production?
• how much is the ration costing the herd manager?
• e.g. CamDAIRY
• whole farm models
• allows what if scenarios to be evaluated ( if
  I dried the herd off today, what would the effect
  on next seasons production be?)
• e.g. UDDER

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Ration evaluation software
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Ration evaluation software
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Ration evaluation software
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Whole farm models - UDDER
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Summary

• What weve covered
• multifactorial nature of disease
  host-pathogen-environment
• a method for investigating herd problems
• causation (cf association)
• measures of health (prevalence, incidence)
• a couple of case studies
• tools for investigating herd problems
• More to follow next year!

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