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TPI Formula - August 2020
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Updated TPI Formula

The August 2020 TPI reflects the new phenotypic base for Calving Traits.

Adjusting the Calving Trait Component of the TPI® Formula

TPI Formula - August 2020

*The value 2363 adjusts for our periodic base change, allowing TPI values to be comparable across time.

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

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 2018 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 = (-.0188 x Milk) + (1.45 x Fat) + (1.85 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 = (.7 x DPR) + (.1 x CCR) + (.1 x HCR) + (.1 x EFC)
Daughter Pregnancy Rate, Cow Conception Rate, Heifer Conception Rate and Early First Calving

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.

Health Trait Index (HT)

The Health Trait Index combines the following health traits, developed by the Council on Dairy Cattle Breeding, into one economic value. The traits included are Milk Fever, Displaced Abomasum, Ketosis, Mastitis, Metritis and Retained Placenta. Higher values are more desirable.

HT = (.34 x MFV) + (1.97 x DAB) + (.28 x KET) + (1.50 x MAS) + (1.12 x MET) + (.68 x RPL)