Breeder Mortality Study
The following information was presented at the 2012 Kidman Springs Field Day by
Nigel Perkins, AusVet Animal Health Services, Alastair Henderson, Mirroong, Steve Banney,
Steve Banney Agribusiness
Slide 1 – Background
•
•
•
•
Producer surveys* indicate breeder mortality estimates between 3-4%
Published papers: 5-10% & occasionally higher
Difficult to measure
If it is markedly higher than expected then we should be doing more about it.
* 2006 NT Pastoral Survey
2007 WA Pastoral Lands Board
Slide 2 – Objectives
1.
2.
3.
4.
5.
6.
Develop a robust method for estimating breeder mortality using available herd data
Collect data from a random/representative sample of properties from several regions
Collect data/info on possible risk factors
Describe mortality
Identify drivers - recommendations
Produce a tool that can be used by producers to monitor their own mortality performance
Slide 3 - Method
•
Use simple calculations based on counts of cattle – livestock schedule
• Opening counts
• Closing counts
• Number branded
• Number of sales
• Number of purchases
Slide 4
•
Mortality rate
• numerator: No. deaths in a year
• denominator: No. animal-years at risk of death
o 1 animal present for the year contributes 1 animal year to denominator
o 1 animal present for half a year contributes 0.5 animal years to denominator
• Adjusted females at risk
opening + 0.5*branded heifers + 0.5*purchased fem
Breeder Mortality Study
Nigel Perkins, AusVet Animal Health Services - Alastair Henderson,
Mirroong - Steve Banney - Steve Banney Agribusiness
Slide 5
State
Region
NT
NT
NT
NT
NT
NT
Barkly
Gulf + Roper
Katherine
Sturt Plateau
VRD
Nth Alice Springs, Tenn.
Creek, Plenty
Southern Alice Springs
Subtotals
NT
NT
WA_Kimb
WA_Kimb
WA_Kimb
WA_Pilb
WA_Pilb
WA_Pilb
QLD
QLD
QLD
Halls Creek, Wyndham-East
Kimberley
Broome, Derby-West
Kimberley
Subtotals
East Pilbara, Port Headland,
Roebourne
Ashburton
Subtotals
QLD southern gulf
QLD northern gulf
Subtotals
TOTALS
Total
Selection
target
Data
collected
from
32
26
6
26
25
51
6
1
1
1
3
4
7
1
1
1
4
3
25
190
2
18
4
21
53
4
3
42
2
6
95
34
6
3
9
3
30
64
336
146
482
3
6
3
3
6
3
6
6
3
9
831
36
45
Slide 6
Region
QLD South Gulf
Qld North Gulf
NT Barkly
NT GKSt
Alice Springs
NT VRD
Kimberley E
Kimberley W
Pilbara
•
•
•
•
•
Region coding for
analyses
1
2
3
4
5
6
7
8
9
Available for
female mort
6
2
6
3
4
4
3
5
3
36
27 properties had 5 yrs of data
Others: 3, 4 or 9 yrs
45 properties provided data
6 had insufficient data to analyse
Another 3-6 produced negative mortality estimates
Available for male
mort
5
2
7
3
4
3
3
4
2
33
Breeder Mortality Study
Nigel Perkins, AusVet Animal Health Services - Alastair Henderson,
Mirroong - Steve Banney - Steve Banney Agribusiness
Slide 7
(opening females + 0.5*female branding + 0.5*female purchases)
QLD SthGulf
QLD NthGulf
NT Barkly
NT GKSt
Alice Springs
NT VRD
Kimberley east
Kimberley west
Pilbara
Total
6
2
6
3
4
4
3
5
3
36
Female
opening count
14,019
14,598
27,949
8,304
3,580
20,255
21,829
11,573
4,954
14,985
Adjusted female
opening count
16,281
16,034
33,247
9,064
4,007
22,509
24,229
13,002
5,585
17,137
Slide 8
Percentage female deaths by region. Bars represent a 95% confidence interval
Breeder Mortality Study
Nigel Perkins, AusVet Animal Health Services - Alastair Henderson,
Mirroong - Steve Banney - Steve Banney Agribusiness
Slide 9
Percentage breeder deaths by region. Bars represent a 95% confidence interval
The red bars are showing the average female mortality
Slide 10
. Separate mortality rates estimated for each property, ordered from smallest to largest.
Bars represent 95% confidence intervals.
Dotted lines represent the 25th (3%) and 75th percentiles (8%)
Solid line shows the median (6%) mortality rate. 13% of properties >10% mortality.
Breeder Mortality Study
Nigel Perkins, AusVet Animal Health Services - Alastair Henderson,
Mirroong - Steve Banney - Steve Banney Agribusiness
Slide 11
Separate mortality rates estimated for each property, ordered from smallest to largest.
Bars represent 95% confidence intervals.
Dotted lines represent the 25th (3.6%) and 75th percentiles (11.7%)\
Solid line shows the median (8%) mortality rate. 44% of properties >10% mortality
Slide 12
Columns represent mean annual rainfall derived from station records for the period.
Bars represent 95% confidence intervals for average rainfall for the period.
Black circles represent the long term average for the region for as long as records were available
Breeder Mortality Study
Nigel Perkins, AusVet Animal Health Services - Alastair Henderson,
Mirroong - Steve Banney - Steve Banney Agribusiness
Slide 13
Combination plot showing average annual rainfall (blue columns),
rainfall range (max – min annual rain) shown as the red bar,
female mortality rate (black circles with bars representing 95% confidence interval)
Slide 14
Multivariable statistical model
Age at last weaning
Supplementary P
Segregation of dry breeders
Age last weaned # Psupplementation
Age wean
<11yrs
<11yrs
<11yrs
11+ yrs
11+ yrs
11+ yrs
<11 yrs
11+ yrs
No
Whole herd
Part herd
Yes
No
Female
Mort Rate
4.1
9.0
8.9
9.1
4.2
4.1
8.0
Breeder
Mort Rate
7.0
11.7
11.9
12.4
5.6
5.7
10.9
P-suppl
No
Whole herd
Part herd
No
Whole herd
Part herd
4.9
9.7
3.9
16.2
8.0
4.7
6.7
12.3
5.7
21.2
12.6
5.4
Breeder Mortality Study
Nigel Perkins, AusVet Animal Health Services - Alastair Henderson,
Mirroong - Steve Banney - Steve Banney Agribusiness
Slide 15
Population attributable fractions (PAFs). How much reduction in the outcome might
be achieved if the adverse effects of a specific explanatory factor were eliminated?
Slide 16 – Tool
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•
•
Excel spreadsheet or web-mounted tool
Producers enter livestock schedule data
Tool produces an estimate of female or breeder mortality
•
Improvements in accuracy
• Accurate counts
• Adjustments (accounting for movements)
o Counts of sales/purchases by month of year
o By breeder vs non-breeder
Slide 17
•
Thank you to:
• producers who willingly provided time and information
• Alastair Henderson & Steve Banney
• – MLA