THE PROFITABLE LIFETIME INDEX (£PLI) FOR DAIRY CATTLE

The Profitable Lifetime Index (£PLI) is a reliable basis for the genetic improvement of dairy cattle productivity, health, welfare, longevity and environmental impact. The versions of the £PLI index developed by Scotland’s Rural College in collaboration with the University of Edinburgh have become very widely used in the UK dairy industry, allowing selection of those breeding animals best suited to UK needs from the massive international pool available. This has helped dairy producers in the UK become more sustainable, helping them to breed animals that are more profitable, fertile and healthy, and that have longer productive lives, as well as reducing greenhouse gas emissions per unit of milk produced. The research led to lifespan being included in the national dairy breeding goal in 1995. £PLI was upgraded in 2003 with the inclusion of health traits (somatic cell counts from milk as an indicator of mastitis/ udder health, and locomotion as an indicator of lameness), and in 2006 with the inclusion of fertility traits. Genetic evaluation – the process of predicting the genetic merit of animals from pedigree and performance data (milk yield, growth, disease incidence etc.) and, recently, molecular genetic data – is a mathematically complex, internationally scarce, but key enabling technology in delivering positive impacts. Edinburgh Genetic Evaluation Services (EGENES) was established in 2005. It provides livestock genetic evaluation and data-handling services, and has helped to accelerate the transfer of research results into industry practice. The work has also influenced practice internationally. For example, the genetic evaluation of body condition score has since been adopted in 15 other major dairying countries, including Canada, the Netherlands and the USA.

 

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