EBVs in Signet's Sheep Evaluations

Signet’s Genetic Evaluation of Different Sheep Breeds

In recent years Signet’s provision of genetic evaluations to the industry has moved from within flock analyses and multi-flock analyses for individual breeds to mixed breed analyses based on breed type.

The three genetic evaluations provided to the sheep industry are as follows:

Terminal Sire Evaluation – Delivered in 2018

This evaluation produces two indexes, a terminal sire index and a maternal (self-replacing) index. The weightings within the terminal sire index vary with breed depending on whether the breed is making widespread use of CT scanning or not. The self-replacing index is a simple maternal index, without any penalty for ewe mature size.

These indexes were developed by Karolina Kaseja, SRUC and based on the principles of desired gains, underpinned by economic principles.

Index weightings can be viewed here

Breeds in the Terminal Sire Evaluation include: Beltex, Berrichon Du Cher, Bleu Du Maine, Blue Texel, Charollais, Dorset, Dorset Down, Dutch Spotted, Hampshire Down, Ile De France, Meatlinc, Oxford Down, Rouge De l'Ouest, Ryeland, Shropshire, Southdown, Suffolk, Texel and Vendeen

Hill Evaluation – Delivered in 2020

The hill evaluation uses an index developed by Janet Roden in 2020. The index is based on economic modelling to develop the ideal index weightings for hill sheep farms, but with modifications to include additional traits deemed important to breeders.

Breeds in the hill evaluation include: Beulah, Black Welsh Mountain, Brecon Hill Cheviot, Hardy Speckle, Hebridean, North Country Cheviot Hill, North Country Cheviot Park, Scottish Blackface, South Country Cheviot, South Welsh Mountain, Swaledale and Welsh Mountain

Maternal (Lowland) Evaluation – To be delivered in 2022

The new maternal index for lowland maternal breeds has been developed for use in 2022. Once again, it is a desired gains index based on economic principles developed with Karolina Kaseja at SRUC.

The index has non-linear weightings on prolificacy to try and enhance twinning rates and a penalty I placed on sheep with high EBVs for ewe mature size that aims to enhance ewe efficiency.

Breeds in the maternal evaluation include: Bluefaced Leicester, Charmoise Hill, Easycare, Exlana, Jacob, Lleyn, Romney Marsh, Roussin, Tefrom and Wiltshire Horn

Estimated Breeding Values in Signet’s Evaluations

A list of traits currently assessed by Signet is shown in the table below, some traits are under development or subject to on-going research.

The core traits that we publish with every run and have done so for many years are as follows:-

• Litter Size (born) – an indicator of female prolificacy
• Maternal Ability – an indicator of milking ability
• Eight Week Weight & Scan Weight – indicators of lamb growth rate
• Muscle Depth & Fat Depth – predictors of carcase quality derived from ultrasound scanning data

Table 1.  Estimated Breeding Values published by Signet Breeding Services