What to do with daily milk data advanced epidemiology

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What to do with daily milk data - advanced
epidemiology

• R Shephard1 and MA Stevenson2
• 1 Gippsland Herd Improvement 2 Foster St Maffra,
  Victoria, Australia
• 2 EpiCentre, IVABS, Massey University, Palmerston
  North, New Zealand

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Roadmap

• Lactation curves
• Shewart charts
• Individual somatic cell count frequency
  histograms
• Individual somatic cell count scatter plots

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Lactation curves

• Herd test data
• rank cows in order of productive merit
• dry off and culling decisions
• somatic cell counts ? dry cow therapy decisions

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Lactation curves

• Lactation curves
• ? herd test milk volume vs days in milk at date
  of herd test
• an additional (objective) way to assess a herds
  feeding program

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Lactation curves
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Non-seasonally calving, pasture concentrate fed
herd Kiama NSW
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Non-seasonally calving, pasture concentrate fed
herd Kiama NSW
Peak yield 28.5 litres at 50 DIM
? 0.04 litres per day ? ? 1.2 litres per month ?
1.2 ? 28.5 4.2 per month
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Seasonally calving, pasture fed herd Palmerston
North
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Seasonally calving, pasture fed herd Palmerston
North
Peak yield 25.7 litres at 50 DIM
? 0.07 litres per day ? ? 2.1 litres per month ?
2.1 ? 25.7 8.2 per month
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Seasonally calving, pasture fed herd Masterton
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Seasonally calving, pasture fed herd Masterton
Peak yield 15.4 litres at 50 DIM
? 0.03 litres per day ? ? 0.9 litres per month ?
0.9 ? 15.4 5.8 per month
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Non-seasonally calving, pasture concentrate fed
herd Kangaloon NSW
Peak yield 26.9 litres at 50 DIM
? 0.03 litres per day ? ? 0.9 litres per month ?
0.9 ? 26.9 3.3 per month
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Lactation curves
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Lactation curves

• Fat to protein ratio vs DIM

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Seasonally calving, pasture fed herd Palmerston
North
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Seasonally calving, pasture fed herd Masterton
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Seasonally calving, pasture fed herd Palmerston
North
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Seasonally calving, pasture fed herd Masterton
Seasonally calving, pasture fed herd Palmerston
North
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Roadmap

• Lactation curves
• Shewart charts
• Individual somatic cell count frequency
  histograms
• Individual somatic cell count scatter plots

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Shewart charts

• Common to monitor aspects of herd performance as
  a function of time
• bulk milk tank volume
• successful inseminations
• bulk milk tank somatic cell counts
• How many abnormal values do we need to accumulate
  before blowing the whistle?

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Non-seasonally calving, pasture concentrate fed
herd Moss Vale NSW
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Non-seasonally calving, pasture concentrate fed
herd Moss Vale NSW
Define what is normal and an acceptable level
of variability
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Non-seasonally calving, pasture concentrate fed
herd Moss Vale NSW
Define what is normal and an acceptable level
of variability
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Non-seasonally calving, pasture concentrate fed
herd Moss Vale NSW
Test 1 a single point outside of control
limits Test 2 3 out of 4 consecutive points
closer to the control limit than to the centre
line Test 3 8 or more successive points on one
side of the centre line
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Roadmap

• Lactation curves
• Shewart charts
• Individual somatic cell count frequency
  histograms
• Individual somatic cell count scatter plots

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ICSCC frequency histograms

• Bin ICSCCs
• 0 - 100,000 cells/mL
• 100,000 - 200,000 cells/mL
• etc
• Count up the number that fall into each group and
  plot as bar charts
• See Ryan (1991)

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Good mastitis control high numbers in 0 -
100,000 cells/mL category low numbers in 500,000
- 1,000,000 cells/mL category
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Poor mastitis control lower numbers in 0 -
100,000 cells/mL category higher numbers in
500,000 - 1,000,000 cells/mL category
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Ineffective teat dip large numbers 100,000 -
200,000 cells/mL category A.bovis ? udder
irritant
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ICSCC frequency histograms

• How can we use ICSCC histograms?
• effective way to monitor responses to suggested
  mastitis controls
• ICSCC frequency histograms change relatively
  quickly after implementation of a mastitis
  control program
• BMSCCs, in contrast, change more slowly

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Non-seasonally calving, pasture concentrate fed
herd Moss Vale NSW
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Non-seasonally calving, pasture concentrate fed
herd Moss Vale NSW
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Roadmap

• Lactation curves
• Shewart charts
• Individual somatic cell count frequency
  histograms
• Individual somatic cell count scatter plots

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ICSCC scatter plots

• Clarify patterns of subclinical mastitis from one
  herd test to the next
• take two consecutive herd tests
• plot first herd test ICSCC value (x axis) vs
  second herd test ICSCC value (y axis)

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Non-seasonally calving, pasture concentrate fed
herd Kiama NSW
New infections
Chronics
Clear
Cured
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Seasonally calving, pasture fed herd Palmerston
North
New infections
Chronics
Clear
Cured
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Seasonally calving, pasture fed herd Palmerston
North
New infections
Chronics
Clear
Cured
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Scatter plots - continued

• Loeffler et al. (1999)
• study of 9369 lactations evaluated effect of milk
  components on dairy cow fertility
• increase in fat-protein ratio a possible risk for
  reproductive failure

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Seasonally calving, pasture fed herd Palmerston
North
Low - High
High - High
Low - Low
High - Low
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Seasonally calving, pasture fed herd Masterton
Low - High
High - High
Low - Low
High - Low
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Roadmap

• Lactation curves

• quantify herd production characteristics

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Roadmap

• Lactation curves
• Shewart charts

• quantify herd production characteristics
• help to decide when to blow the whistle

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Roadmap

• Lactation curves
• Shewart charts
• ICSCC frequency histograms

• quantify herd production characteristics
• help to decide when to blow the whistle
• monitor response to controls

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Roadmap

• Lactation curves
• Shewart charts
• ICSCC frequency histograms
• ICSCC scatter plots

• quantify herd production characteristics
• help to decide when to blow the whistle
• monitor response to controls
• identify infection patterns