Modernizing Canada’s Lifetime Performance Index (LPI)

Abstract

National selection indexes combining important traits are frequently used by dairy farmers, breeders, and A.I. companies to achieve their breeding goals. The Canadian dairy industry has made significant genetic progress with two national selection indexes, the Lifetime Performance Index (LPI) and Pro$, which are now double the rate compared to the pre-genomics era. Since its introduction in 1991 the LPI formula has changed alongside the expansion of national breeding objectives. With the introduction in recent years of genetic evaluations for its portfolio of traits related to sustainability, the timing was right for Lactanet to modernize several aspects of Canada’s LPI, effective April 2025. A key strategic change is the creation of six subindexes, which are each published on their own using a standardized scale with an average of 500 and standard deviation of 100. Subindexes include the Production Index (PI), Longevity & Type Index (LTI), Health & Welfare Index (HWI), Reproduction Index (RI), Milkability Index (MI), and Environmental Impact Index (EI). For the Holstein breed, the relative weights placed on these subindexes are 40% PI, 32% LTI, 8% HWI, 10% RI, 5% MI, and 5% EI. The six other dairy breeds evaluated have differing relative weights in accordance with the respective breed objectives. A second important change is an increased focus on presenting the genetic response over the next five years that can be expected for each trait based on the average level of selection gain realized for LPI. While this approach recognizes the impact of direct inclusion of a trait in one of the six LPI subindexes, it also reflects the expected response for correlated traits. Defining six subindexes that contribute to LPI demonstrates the increased diversity of traits currently evaluated and acknowledges the continued expansion of Canada’s overall breeding goal for dairy cattle breeds.