Sow Longevity – Its
Improvement and Economic
Importance
Ken Stalder
Department of Animal Science
Iowa State University
Reported Averages
Replacement Culling Avg. Parity Death
Rate, % Rate,% At Culling Loss, %


PigCHAMP
Pigtales
60
53
42
47
3.8
Not Reported
7.8
Worldwide Replacement
Rates




Australian average 63.8% replacement from
1992 through 2002
Brazil 2002 averaged 55% replacement rate,
43% culling rate, 5.5% death loss, and
average parity of culled sows of 4.16.
Canada 2002 averaged 58% replacement
rate, 39.5% culling rate, 6.5% death loss,
and average parity of culled sows of 4.71.
Japan 2000 averaged 47.6% replacement
rate, 28.6% culling rate, 5.3% death loss,
and average parity of culled sows of 3.8.
How Do Top Herds
Perform?

2002 PigCHAMP data Upper 10 Percentile





Replacement rate 32.7%
Culling rate 22%
Death Loss 2.8%
Average parity at culling 5.5
Koketsu et al. (1999)



A cohort of females born in 1990
Average lifetime pig production 67.2 pigs
Average parity at removal was 5.6 parities
Why should we be
concerned with longevity?

Performance differences







Number born alive
Litter weaning weight
Grow – Finish Performance
Better protection from disease??
Introduction of more gilts
Associated costs
Welfare issue
Reasons For Culling
Reason
 Reproductive failure
 Old age
 Performance
 Feet and leg problems
 Death
 Post-farrowing problems
 Other
Percentage Culled
30 - 35
15 - 20
15 - 20
10 - 15
5 - 10
3 - 5
5 - 10
Cost of Replacing a Sow






Replacement gilt
Facility, feed, and labor during isolation and
acclimation
Vaccination and other veterinary expenses
Disease risk
Opportunity cost (interest rate)
Performance difference between a gilt and
mature sow.
% of Sow Herd
Ideal Parity Distribution
20
18
16
14
12
10
8
6
4
2
0
Industry
Book
1
2
3
4
5
Parity
6
7
>7
Impact of Distribution on
Productivity

Average parity of sow herd 3.6 (industry) and
3.86 (book)
National Swine Improvement
Federation Parity adjustment factors
for number born alive
Parity
1
2
3
4-5
6
7
8
9+
Number born alive
1.2
0.9
0.2
0
0.2
0.5
0.9
1.1
National Swine Improvement
Federation Parity adjustment factors
for 21-day Litter Weight
Parity
1
2
3
4
5
6
7
8
9+
21-day Litter Weight Adj.
16.2
0
1.0
3.8
6.2
9.5
11.6
15.2
21.5
Given 10.2 pigs born alive from an
average parity of sows farrowed of 3.5
Number
Number Born Alive
Per 100
Maximum Born
Sows
Alive
Parity
Value of
Pigs
Produced @ Value Per
$30 / pig
Year, $
Difference
from
Maximum,
$ / Year
2
9.79
979
$29,370
$1,527,240 $87,360
3
10.05
1005
$30,150
$1,567,800 $46,800
4
10.21
1021
$30,630
$1,592,760 $21,840
5
10.31
1031
$30,930
$1,608,360 $6,240
6
10.35
1035
$31,050
$1,614,600 $0
7
10.35
1035
$31,050
$1,614,600 $0
8
10.33
1033
$30,990
$1,611,480 $3,120
Ideal Distribution
Given
• Maximum Parity
•Culling per parity at 15% or 35% per year
Parity
1
1 100.000
2
3
4
5
6
7
8
2
54.1
45.9
3
38.9
33.0
28.1
4
31.4
26.7
22.7
19.3
5
27.0
22.9
19.5
16.6
14.1
6
24.1
20.5
17.4
14.8
12.6
10.7
7
22.1
18.8
16.0
13.6
11.5
9.8
8.3
8
20.6
17.5
14.9
12.7
10.8
9.1
7.8
6.6
Take Home Point:
Economic Importance of Sow
Longevity


Reduced sow longevity (parity of sow at
culling) results in fewer litters in which
a sow has an opportunity to be
sufficiently productive in order for her
purchase to be profitable.
Because of the cost of replacement
females and short herd life, commercial
swine producers should economically
evaluate their replacement breeding
herd decisions.
How do you evaluate how long
a sow needs to remain in
the breeding herd to be a
profitable investment?
Development of the Sow
Longevity Calculator




Farrow-to-Finish and Breed-to-Wean custom
spreadsheets available
Uses Net Present Value analysis
Version 2.0 Now Available
Producer supplies


Herd specific production data
Operation specific financial information


Income
Fixed and variable costs
Data Entry Sheet
Price of Gilt
Annual Discount Rate
Parity Discount Rate
Percentage of gilts purchased
that do not enter the breeding
herd
Development Feed Costs
Other Development Costs
Total Development Costs
Total Gilt Price
Number of Pigs Born Alive/Litter
Birth to Weaning Death Loss
Nursery Death Loss
Grow-Finish Death Loss
Death Loss on Sows
Wt of gilts @ culling
$/cwt for cull gilts
Revenue for cull gilts
$ 200.00 Number of Pigs Sold/Litter
10.00% Weight Sold, cwt.
4.48% $/cwt. Hogs
$
10% Revenue/Litter
$ 28.06 Feed Cost/Litter
$
7.50 Other Expenses
$ 35.56 Net Income/Litter
$ 248.53 Number of sows
10.2
Litters/sow/Yr
11.77% Total Litters/Yr
Average Parity of
2.45% Farrowed Sows
2.80% Years of Sow
5.90% Weight of Sow @ Culling
300
$/Cwt for Culls
$ 44.00 Cull Value
$ 13.20
$
$
$
$
8.53
2.56
44.00
961.18
621.79
185.07
154.31
2,400
2.23
5,352
3.50
1.57
400
$35.83
$ 134.86
Feed Data Entry
Class
Pigs
Sows
Gilts
Weight
5-10
10-15
15-25
25-50
50-80
80-120
120-170
170-Finish
Feed
SEW Diet
Transition Diet
Phase II Diet
Phase III Diet
Grower Diet I
Grower Diet II
Finisher Diet I
Finisher Diet II
Total
Nursery-Finish Feed/Gain
Gestation Diet
Lactation Diet
Total
Replacement Gilt Diet
TOTAL
Feed
(lbs/hd)
2.00
5.00
15.00
50.00
65.00
110.00
160.00
315.00
722.00
2.93
868.06
285.00
1,153.06
350
No. of
Head)
9.00
8.93
8.85
8.78
8.72
8.66
8.60
8.54
Total
(tons)
0.01
0.02
0.07
0.22
0.28
0.48
0.69
1.34
3.11
1.00
1.00
0.43
0.14
0.58
1
Price
Feed
($/ton)
Cost ($)
$1,275.00
$11.47
$722.00
$16.11
$316.00
$20.99
$210.00
$46.11
$177.50
$50.31
$172.00
$81.93
$154.60 $106.36
$144.00 $193.68
$169.44 $526.96 $
$160.35
$177.08
0.18
$160.35
3.86
$ 161.02
COST/HEAD
61.71
$69.60
$25.23
94.83
TOTAL FEED
COST/PURCHASED
FEMALE
$28.06 $
122.89
$621.79
Facilities and Other Costs
Operation Total
$
4,290,000.00
50%
10%
Per Litter
Investment / Facility Cost
% Enterprise Equity
% Interest Rate
Annual Principal &
Interest Payments
($349,088.87) $
Other Operating Expenses
Veterinary and Medicine /
Litter
Breeding / Litter
Waste Handling / Litter
Insurance / Litter
Labor / Litter
Utilities / Litter
Marketing and Hauling /
Litter
Maintence and Repairs /
Litter
Total Other Costs / Litter
Non-Feed Costs/Pig
$
$
$
$
$
$
159,757.20
80,280.00
2,676.00
5,352.00
417,777.12
194,010.00
(65.23)
$
$
$
$
$
$
29.85
15.00
0.50
1.00
78.06
36.25
$
45,652.56 $
8.53
$
$
84,989.76 $
1,339,583.51 $
$
15.88
250.30
29.33
Adjusting for Parity
Performance Differences
Parity
Adjustments Number Born Alive
1
9
2
9.3
3
10
4
10.2
5
10.2
6
10
7
9.7
8
9.3
9+
9.1
Parity Adjustment Caution


Only make these adjustments if you are
extremely confident in the production
numbers by parity.
Do not adjust if values from your herd
are based on small numbers


Within a parity
Across all parities
What does all of this get
you?
Net Present Value Analysis
What does the NPV number mean?
 > 0 means the investment is profitable in the long term.
 < 0 means the investment will lose money in the long
term.
Sensitivity Analyses – Gilt
Purchase Price (F-F)
Net Present Value per gilt by parity when the price of replacement gilt varies.
Gilt Purchase Price
1
2
3
125
$3.20
$52.54 $125.92
150 ($24.58)
$24.76 $98.14
175 ($52.36)
($3.01) $70.36
200 ($80.14)
($30.79) $42.58
225 ($107.91)
($58.57) $14.80
250 ($135.69)
($86.35) ($12.97)
275 ($163.47)
($114.13) ($40.75)
300 ($191.25)
($141.90) ($68.53)
4
$203.29
$175.51
$147.74
$119.96
$92.18
$64.40
$36.63
$8.85
5
$277.35
$249.57
$221.79
$194.01
$166.24
$138.46
$110.68
$82.90
6
$341.67
$313.90
$286.12
$258.34
$230.56
$202.78
$175.01
$147.23
Sensitivity Analyses – Number
Born Alive
Net Present Value per gilt by parity when the number of pigs born alive varies.
Number Born Alive/Litter
1
2
3
8.45 ($151.50)
($170.46) ($162.46)
8.70 ($141.31)
($150.51) ($133.16)
8.95 ($131.11)
($130.55) ($103.87)
9.20 ($120.92)
($110.60)
($74.58)
9.45 ($110.72)
($90.65)
($45.29)
9.70 ($100.53)
($70.70)
($16.00)
9.95
($90.33)
($50.74)
$13.29
10.20
($80.14)
($30.79)
$42.58
10.45
($69.94)
($10.84)
$71.87
10.70
($59.75)
$9.11
$101.17
10.95
($49.55)
$29.07
$130.46
11.20
($39.36)
$49.02
$159.75
11.45
($29.16)
$68.97
$189.04
11.70
($18.97)
$88.92
$218.33
11.95
($8.77)
$108.88
$247.62
4
($147.64)
($109.42)
($71.19)
($32.96)
$5.27
$43.50
$81.73
$119.96
$158.19
$196.42
$234.65
$272.87
$311.10
$349.33
$387.56
5
($133.47)
($86.69)
($39.90)
$6.88
$53.66
$100.45
$147.23
$194.01
$240.80
$287.58
$334.36
$381.15
$427.93
$474.71
$521.50
6
($126.45)
($71.48)
($16.51)
$38.46
$93.43
$148.40
$203.37
$258.34
$313.31
$368.28
$423.25
$478.22
$533.19
$588.16
$643.13
Sensitivity Analyses – Market
Hog Price
Net Present Value per gilt by parity for varying market hog price.
$/CWT for Hogs
1
2
$
32.00
(306.43)
(480.72)
$
34.00
(268.71)
(405.74)
$
36.00
(231.00)
(330.75)
$
38.00
(193.28)
(255.76)
$
40.00
(155.57)
(180.77)
$
42.00
(117.85)
(105.78)
$
44.00
(80.14)
(30.79)
$
46.00
(42.42)
44.20
$
48.00
(4.71)
119.19
$
50.00
33.01
194.17
$
52.00
70.72
269.16
$
54.00
108.44
344.15
$
56.00
146.16
419.14
3
($637.16)
($523.87)
($410.58)
($297.29)
($184.00)
($70.71)
$42.58
$155.87
$269.17
$382.46
$495.75
$609.04
$722.33
4
5
($784.05) ($924.64)
($633.38) ($738.20)
($482.72) ($551.75)
($332.05) ($365.31)
($181.38) ($178.87)
($30.71)
$7.57
$119.96
$194.01
$270.63
$380.46
$421.30
$566.90
$571.96
$753.34
$722.63
$939.78
$873.30 $1,126.22
$1,023.97 $1,312.66
6
($1,061.79)
($841.77)
($621.74)
($401.72)
($181.70)
$38.32
$258.34
$478.36
$698.38
$918.40
$1,138.43
$1,358.45
$1,578.47
Sensitivity Analyses – Feed Costs
Per Market Hog
Net Present Value per gilt by parity for varying feed costs.
Feed Cost/Head
1
2
$
46
33.50
195.16
$
49
10.78
149.97
$
52
(11.95)
104.78
$
56
(34.68)
59.59
$
59
(57.41)
14.40
$
62
$
$
$
$
$
65
68
71
74
77
(80.14)
(102.86)
(125.59)
(148.32)
(171.05)
(193.78)
(30.79)
(75.98)
(121.17)
(166.36)
(211.55)
(256.74)
3
383.94
315.67
247.40
179.13
110.85
4
573.94
483.14
392.35
301.55
210.75
5
755.78
643.43
531.07
418.72
306.37
6
921.29
788.70
656.11
523.52
390.93
42.58
(25.69)
(93.96)
(162.23)
(230.50)
(298.77)
119.96
29.16
(61.63)
(152.43)
(243.22)
(334.02)
194.01
81.66
(30.69)
(143.05)
(255.40)
(367.75)
258.34
125.75
(6.84)
(139.43)
(272.02)
(404.60)
Points: Factors
Take Home Points
Influencing Net Present Value of a
Breeding Herd Replacement Female
Major Factors

Pigs produced (number born alive, mortalities
at all levels, and substandard pigs at marketing)



Price received for pigs marketed



± ½ pig changes parity at which positive NPV is
reached
5% change in number born alive
± 2$ - 4$ changes parity at which positive NPV is
reached
4.5% to 9% change in price
Feed costs (feed efficiency and ingredient cost)


± 3$ per head changes parity at which positive NPV is
reached
4.8% change in feed costs
Take Home Points: Factors
Influencing Net Present Value of a
Breeding Herd Replacement Female
Relatively Minor Factors

Replacement Gilt Cost





± 50$ change in gilt price required to change parity at
which positive NPV is reached
25% change in number born alive
Interest Rate
Operation Equity
Cull Animal Market Price
Factors Influencing Sow
Longevity



Host of management effects
 feed intake, lactation length, gestation
housing, etc.
Factors under some genetic control
Backfat of gilt at selection effects sow
longevity
Summary



Improved longevity can increase profitability
Focus on management practices that
improve longevity
More sows should be culled because of poor
performance rather than reproductive
reasons.
Those Interested in The
Spreadsheet
Spreadsheet designed to evaluate the investment in a
replacement gilt available at:
Iowa Pork Industry Center
515-294-4103
Iowa Pork Industry Center Web Site:
http://www.extension.iastate.edu/ipic
Porkline (Iowa Only) 800-808-7675
e-mail me at stalder@iastate.edu
Thank You for Your Time and
Attention
Are there any questions?