Lifetime Performance Index (LPI) Formula – April 2023

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

2019

46 .5681 32 .7170 22

.9592

Brown Swiss

966

55 .5458 27 .6835 18

.8328

Canadienne

932

55 .4480 30 .6537 15

.8387

Guernsey

648

50 .5547 35 .7406 15 .6895
Holstein

2255

40 .5420 40 .7971 20

.6869

Jersey

1088

50 .5979 30 .6281 20

.7645

Milking Shorthorn

1076

56 .5419 30 .8335 14

1.0332

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

-438

-293 -281 -256 -432 -208

-178

Fat Yield

-21

-10 -6 -10 -26 -16

-13

Protein Yield

-17

-10 -5 -9 -19 -11

-6

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.