Lifetime Performance Index (LPI) Formula – April 2024

Where the relative emphasis placed on each of the three main components in each breed is presented in the following table along with the multiplicative factors for each component.

Breed
LPI Constant
Production
Durability
Health & Fertility
Emphasis
Factor
Emphasis
Factor
Emphasis
Factor
Ayrshire
2036
46
.5690
32
.7454
22
.9461
Brown Swiss
971
55
.5520
27
.6805
18
.8108
Canadienne
919
55
.4456
30
.6615
15
.8185
Guernsey
646
50
.5356
35
.7454
15
.6897
Holstein
2302
40
.5442
40
.7631
20
.6778
Jersey
1089
50
.5991
30
.6324
20
.7690
Milking Shorthorn
1091
56
.5450
30
.8259
14
1.0169

Production Component (PROD):

PROD = [WPYx(PY-AvgPY)/SDPY] + [WPDxPD/SDPD] + [WFYx(FY-AvgFY)/SDFY] + [WFDxFD/SDFD]

Where PY = Protein Yield, PD = Protein Deviation, FY = Fat Yield and FD = Fat Deviation, which are standardized using the appropriate averages (Avg) and standard deviations (SD) and then multiplied by their respective relative weight (W), all of which are breed specific as outlined in the following table.

Parameter
Trait
Ayrshire
Brown Swiss
Canadienne
Guernsey
Holstein
Jersey
Milking Shorthorn
EBV Averages
Milk Yield
-522
-355
-325
-331
-521
-284
-208
Fat Yield
-25
-13
-7
-13
-31
-20
-14
Protein Yield
-20
-13
-6
-11
-23
-14
-7
EBV Standard Deviations
Milk Yield
620
500
450
550
740
760
450
Fat Yield
25
20
11
23
28
34
19
Fat Deviation
.21
.20
.20
.27
.28
.38
.16
Protein Yield
21
17
7
15
21
25
11
Protein Deviation
.11
.12
.13
.10
.12
.16
.09
Relative Weights Within the Production Component
Fat Yield
5.0
4.5
4.5
4.5
6.0
4.5
4.5
Fat Deviation
 
0.5
0.5
0.5
 
0.5
0.5
Protein Yield
5.0
4.5
4.5
4.5
4.0
4.5
4.5
Protein Deviation
 
0.5
0.5
0.5
 
0.5
0.5

Durability Component (DUR):

DUR = [WHL x (HL – 100)/5] + [WMS x MS/5] + [WF&L x F&L/5] + [WHH x (HH – 100)/5] + [WDS x DS/5] + [WRP x RP/5]

Where HL = Herd Life, MS = Mammary System, F&L = Feet and Legs, HH = Hoof Health, DS = Dairy Strength and RP = Rump, and each trait is standardized using the appropriate averages and standard deviations and then multiplied by their respective relative weight (W) that is breed specific as outlined in the following table.

Parameter
Trait
Ayrshire
Brown Swiss
Canadienne
Guernsey
Holstein
Jersey
Milking Shorthorn
Relative Weights Within the Durability
Component
Herd Life
4.0
4.0
2.0
3.4
2.0
2.0
2.6
Mammary System
3.8
3.2
5.5
3.2
3.7
4.0
4.0
Feet & Legs
2.2
1.6
2.5
2.4
2.1
4.0
2.6
Hoof Health
 
 
 
 
0.7
 
 
Dairy Strength
 
 
 
1.0
1.0
 
0.8
Rump
 
1.2
 
 
0.5
 
 

Health & Fertility Component (H&F):

H&F = [WDF x (DF-100)/5] + [WMR x (MR-100)/5] + [WSCS x (SCS-100)/5] + [WUD x UD/5] + [WMSP x (MSP-100)/5] + [WMT x (MT-100)/5]

Where DF = Daughter Fertility, MR = Mastitis Resistance, SCS = Somatic Cell Score, UD = Udder Depth, MSP = Milking Speed and MT = Milking Temperament.  The relative weights for each trait (i.e.: WDF, WMR, WSCS, WUD, WMSP and WMT, respectively), which are specific to each breed, are provided in the following table.

Parameter
Trait
Ayrshire
Brown Swiss
Canadienne
Guernsey
Holstein
Jersey
Milking Shorthorn
Relative Weights Within the Health & Fertility Component
Daughter Fertility
4.0
4.0
4.0
6.7
6.7
5.0
2.0
Mastitis Resistance
1.0
 
 
 
3.3
5.0
 
Somatic Cell Score
 
3.0
3.0
2.0
 
 
4.8
Udder Depth
 
1.0
2.0
1.0
 
 
2.4
Milking Speed
3.0
2.0
1.0
0.3
 
 
0.8
Milking Temperament
2.0
 
 
 
 
 
 

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By Brian Van Doormaal
Brian has dedicated his professional career of nearly 37 years involved in the genetic improvement of dairy cattle in Canada. He is well-known for his numerous extension articles and public speaking engagements in both official languages.