TPI Formula, Holstein Association USA


Note:	New udder composite formula
	New PTATs with larger standard deviation
	Added Daughter Stillbirth
	Multiplier changed from 3.6 to 3.7
	Constant changed from 1548 to 1575

Where:	PTAP	= PTA Protein	PTAF	= PTA Fat
	PTAT	= PTA Type	DF	= STA Dairy Form
	UDC	= Udder Composite	FLC	= Feet & Legs Composite
	PL	= PTA Productive Life	SCS	= PTA Somatic Cell Score
	DPR	= PTA Daughter Pregnancy Rate	DCE	= PTA Daughter Calving Ease
	DSB	= PTA Daughter Stillbirth

Change to TPI formula - effective May 2007

The TPI formula will be changed in May 2007 to incorporate more emphasis on health and fertility traits. This will lead to higher daughter pregnancy rates, longer productive life, lower somatic cell score, less calving difficulty and fewer stillbirths. In the new formula, type receives the same emphasis while production emphasis has been reduced.

To better reflect our new objective the acronym TPI will be changed from Type and Production Index to Total Performance Index.

The key features of the new TPI formula are as follows:

47%	emphasis on production	(Fat and Protein & part of PTAT)
20%	emphasis on udder health	(SCS, UDC & part of PTAT)
19%	emphasis on early breeding	(DPR, PL & DF)
8%	emphasis on mobility	(Feet & Leg composite & part of PTAT )
3%	emphasis on calving ability	(Daughter Calving Ease & Stillbirth)
3%	emphasis on body size	(part of PTAT )