Relationships between bull proofs for lifespan (LS) in the united kingdom (UK) and various countries.

摘要

Longevity or lifespan has proved to be an important trait when it comes to profitability for the dairy farmer. Selecting for longer herdlife not only reduces the replacement rate and thereby the replacement cost, but also gives the opportunity to cull for low production (as opposed to health problems) and increases the milk yield through a higher proportion of mature cows in the herd. Predicted Transmitting Abilities (PTA's) for LS are calculated from a bivariate analysis including indirect information in the form of a phenotypic index of four linear type traits (fore udder attachment, foot angle, udder depth and teat length) closely related to longevity, and from direct lactation information, i.e. survival measured in number of lactations corrected for milk yield (Brotherstone et RAID., 1998). Genetic evaluations for LS were introduced in the United Kingdom (UK) in August 1998 (Mrode et RAID., 1999).