Lifetime Performance Index (LPI) Formula – April 2022

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Source: Lactanet, Brian Van Doormaal

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 2004 46 .5685 32 .7215 22 .9561
Brown Swiss 959 55 .5440 27 .6786 18 .8349
Canadienne 932 55 .4565 30 .6653 15 .8759
Guernsey 644 50 .5540 35 .7523 15 .6923
Holstein 2200 40 .5408 40 .8243 20 .6967
Jersey 1087 50 .5970 30 .6387 20 .7483
Milking Shorthorn 1065 56 .5389 30 .7992 14 1.0363

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 -372 -221 -256 -179 -328 -146 -195
Fat Yield -18 -7 -5 -8 -22 -13 -13
Protein Yield -14 -8 -4 -7 -15 -8 -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