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£PLI – Profitable Lifetime Index

Replacement heifers for the 180 cow CAFRE Dairy Herd are bred from sires selected initially on £PLI (Profitable Lifetime Index) and then on a number of individual genetic index traits including milk protein, fertility, lifespan and somatic cell count (SCC). The aim of the CAFRE dairy herd breeding programme is to improve the overall genetic merit of the CAFRE Dairy Herd through sire selection and genomic analysis. The genetic merit of the CAFRE Dairy Herd and the annual sire selection criteria are published on the CAFRE website to demonstrate to students and farmers the benefits of genetic improvement and the use of breeding technologies such as the increasing number of new genetic indices which have been added to £PLI in recent years.

£PLI is a within breed sire ranking index. The £PLI value represents the additional profit a high £PLI bull is expected to return from each of its milking daughters over her lifetime compared with an average bull of £0 PLI. The £PLI reflects the latest UK market and farming conditions. The £PLI is a weighted economic index with different weights given to a wide range of sub-indices or Predicted Transmitting Abilities (PTAs) for genetic parameters ranging from milk yield and milk quality through to lifespan, fertility, mastitis and TB resistance. The Agricultural and Horticultural Development Board (AHDB) is the UK organisation responsible for maintaining and updating £PLI three times each year.

More information on £PLI and important sub-indexes from which £PLI is derived can be found on the AHDB website through clicking on each parameter below:

Sire selection within the CAFRE Dairy Herd

The starting point for sire selection each year is to review the Herd Genetic Report. This report is available to dairy farms that fully milk record their dairy herd. Herd Genetic Reports allow farmers to evaluate the genetic potential of their dairy herd through reviewing the genetic merit for production and health traits for either individual animals or lactation number groups. Analysis of the Herd Genetic Report will indicate if the key breeding indices are improving or whether more selection pressure needs to be applied to particular breeding sub-indices. Following a review of the herd genetic report, selection criteria are set for £PLI and for a number of breeding sub-indices including: calving ease, fertility, lifespan, milk protein % and SCC. The list of available Holstein sires, and available Holstein genomic young sires

is downloaded from the AHDB website as spreadsheets. The spreadsheets are screened initially by £PLI and then for each of the breeding sub-indices to determine which sires meet the selection criteria. A shortlist is then drawn up of potential sires for milking cows and sires for maiden heifers that are available with sexed semen. The availability of semen from sires on the shortlist of sires is then checked with the semen supply companies. The shortlist of sires is also run through commercial mating software to ensure that the sires chosen will not result in inbreeding. If sufficient sires do not meet the selection criteria, or if sexed semen for use on maiden heifers is not available, the selection criteria may need to be relaxed to bring more potential sires into the shortlist.

The sires selected for the CAFRE dairy herd for breeding replacement heifers each breeding season are listed in the attached document.

Within the CAFRE Dairy Herd, analysis of breeding records across a number of breeding seasons has demonstrated a positive correlation between sire fertility index on conception rates and calving interval. This analysis carried out several years ago reinforced the benefit of breeding for daughter fertility to the CAFRE dairy team with the result that Fertility Index continues to be a key parameter for selecting sires for replacement breeding replacement heifers on an annual basis.