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TPI Formula - April 2015

Updated TPI Formula

The Holstein Association USA board of directors approved the implementation of an updated TPI formula with the April 2015 official genetic evaluation. The updated formula incorporates two interesting new components: Feed Efficiency (FE) and a Fertility Index (FI). These components will not only improve the value of the TPI as a selection tool but also bring more focus to some important traits. The advantage of using a selection index such as TPI is that you can use it to make improvement in several traits at the same time. This is well illustrated when looking at two antagonistic traits such as production and fertility.

TPI Formula - April 2015

*The value 2187 adjusts for our periodic base change, allowing TPI values to be comparable across time.
Formula last updated December 2014

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

The new Feed Efficiency (FE) value rewards cattle with the ability to produce large volumes of milk without having to consume a great deal of feed, based on the following formula:

Feed Efficiency = (Dollar value of milk produced) - (Feed costs for extra milk) - (Extra maintenance costs)

The new Fertility Index (FI) 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:

Fertility Index = 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.

Webinar: December 2014 TPI® & Base Change

Dr. Tom Lawlor, Holstein Association USA Executive Director of Research & Development discusses what dairy producers can expect to see with the December 2014 national genetic evaluation in regards to the updated Holstein Association USA TPI® formula update and the genetic base change.




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