After more than twenty years with the Lifetime Profit Index (LPI) as Canada’s national genetic selection index, Canadian Dairy Network (CDN) has decided to adjust the scale of expression for all dairy breeds in conjunction with the April 2013 genetic evaluation release. The CDN Board of Directors took this action following more than a year of consultation with the various breed associations and industry partners. The April 2013 implementation of the revised LPI scale of expression also includes an update of the standard deviation values for fat and protein yields in the formula in addition to the annual genetic base adjustments.
New LPI Scale
Since its beginning in 1991, the Lifetime Profit Index (LPI) has helped breeders and A.I. organizations rank bulls, cows and heifers to optimize selection and mating decisions, which translates to high rates of genetic progress for traits of importance. Effective April 2013, the scale for LPI values in each dairy breed will be half of what it has been. In order to maintain the level of LPI for the highest progeny proven bulls, a “constant” will be added to the formula For the Holstein breed, the “constant” will be 1700 points as presented in Table 1, which includes all breeds. This change in scale has no impact on how animals in each breed rank although reducing the range will create more animals tied at some LPI values.
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