A Genetic Study on Lifetime Traits for Experimental Herds of Friesian Cattle

This study analyzed data from 5,518 lactations involving 1,749 Friesian cows raised in two experimental herds between 1992 and 2022. The aim was the estimation of genetic parameters for longevity traits using a multiple-trait animal model, including lifetime (LT), lifetime days in milk (LTDIM), and lactations (TL), lifetime production (LTMY), and age at first calving (AFC). On average, cows lived for 80.4 months, with 41% of their lifetime in milk production. They averaged 3.2 lactations, starting at 32.7 months. Heritability estimates for longevity traits were 0.09-0.12, suggesting limited direct selection potential. Strong genetic and phenotypic correlations 0.88–0.96 were observed between lifespan traits and total milk production. Similar correlations were found between partial lifetime milk yield traits for the first three lactations and total lifetime milk yield ranged 0.44-0.97. Genetic correlations ranged 0.88-0.99 between lifetime traits were consistently high, mirroring phenotypic correlations. Notably, there were increasing in heritability estimates for partial performance traits with more lactations considered, and correlations between partial and lifetime traits were improved with additional data. These findings suggest the feasibility of early indirect selection for longevity through correlated responses in early performance traits, particularly early lactation milk production, to enhance overall lifetime productivity.