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TPI Formula - August 2017

Updated TPI Formula

The Holstein Association USA board of directors approved the implementation of an updated TPI formula with the August 2017 official genetic evaluation. The updated formula incorporates the following changes:

  • Adding the trait Cow Livability with a 3% weighting, and adjusting the weighting of Productive Life from 7% to 4%. The Livability trait explains a portion of Productive Life.
  • Changing the weighting of Fat and Protein to 17% and 21% to be more in line with how producers are paid for components.
  • Increasing the weighting on Feed Efficiency from 3% to 8%.
TPI Formula - August 2017

*The value 2187 adjusts for our periodic base change, allowing TPI values to be comparable across time.
Formula last updated April 2015

  PTAP = PTA Protein   PTAF = PTA Fat
  FE = Feed Efficiency   BWC = Body Weight Composite
  PL = PTA Productive Life   LIV = PTA Cow Livability
  FI = Fertility Index   DF = STA Dairy Form
  SCS = PTA Somatic Cell Score   PTAT = PTA Type
  UDC = Udder Composite   FLC = Feet & Legs Composite
  DCE = PTA Daughter Calving Ease   DSB = PTA Daughter Stillbirth
  Weighting of Major Categories  
    Production 46% (Fat, Protein, Body Weight Composite, and Feed Efficiency)
    Health & Fertility 28% (SCS, PL, LIV, FI, DCE and DSE)
    Conformation 26% (PTAT, UDC, FLC and Dairy Form)

Use of the TPI Formula will lead to:

  • Additional pounds of Fat and Protein, with slightly more gain in Butterfat.
  • Body Weight of the next generation of cows should be consistent with the current population.
  • Production increase, and body weight staying the same, leading to an improvement in Feed Efficiency for the Breed.
  • An added benefit of the better control of the size of our cattle is a lowering of the incidence of difficult births, with a slight improvement in the daughter's ability to deliver a live calf.
  • Higher economic returns by lowering the incidence of on-farm deaths and improving the productive period of months-in-milk.
  • Conformation of our cattle will continue to improve from genetic improvement of overall conformation (PTAT), udders and feet & legs.
  • Dairy farmers using the TPI formula will be breeding a more profitable herd of cattle.



Feed Efficiency

Feed Efficiency is the net profit a farmer receives from an increase in production. Feed Efficiency is calculated from the following information:

(Dollar Value of milk produced) - (Feed costs of extra milk) - (Extra maintenance costs)

Dollar Value of milk produced is based upon the 2017 Cheese Merit $ information from USDA-AGIL. Feed costs are the increased cost of feed per lactation that is eaten by higher producing cows. Maintenance costs are associated with body maintenance based upon the National Research Council plus increased housing costs minus income from heavier calf weights. Body weight is predicted from HAUSA classification data. The formula was developed as a part of the USDA multi-state research project on feed efficiency and a cooperative project with researchers at the University of Wageningen in the Netherlands.

FE = (-.0187 x Milk) + (1.28 x Fat) + (1.95 x Protein) - (12.4 x BWC)

Fertility Index (FI)

The Fertility Index combines several reproductive components into one overall index: ability to conceive as a maiden heifer, ability to conceive as a lactating cow, and a cow's overall ability to start cycling again, show heat, conceive, and maintain a pregnancy. The Fertility Index is derived from the formula:

FI = 18% Heifer Conception Rate (HCR) + 18% Cow Conception Rate (CCR) + 64% Daughter Pregnancy Rate (DPR)

Breeding cows based on the updated TPI formula results in more profit, efficiency, and fertility. It impacts dairy producers' bottom lines today, while the genetic superiority expressed by these cows will be passed onto the next generation.