Single Step Evaluation

Single Step Evaluation

In August 2022 the South Devons became the first beef breed in the UK to launch Breedplan Single Step Evaluations.

(This progressive move has since been followed by other beef breeds.)

The Society first started to look at the genetic make-up of the South Devon breed in the early 2000’s, and right from the start used the most up to date technology – Single-Nucleotide Polymorphism (SNPs) which meant it could easily provide a robust reference population of genetics to add to the existing pedigree and performance data computed by ABRI to produce genetic evaluations.

The first obvious improvement to conventional Estimated Breeding Values (EBVs) was a jump in accuracy percentages, particularly for unproven younger animals, thus giving more confidence to buyers.

Dr Brad Crook from ABRI, Australia explains, “When we talk about two full sib bulls, we can correctly say they have the same sire and dam, receiving 50% of their genetic material from each parent. However, what we cannot correctly say is that each receives the same combination of genetic material from each parent. The mix of DNA from the sire – which copies of which positions on each chromosome – is random, and likewise for the mix of DNA from the dam. Unless they are identical twins – where one embryo has split into two – we expect full sibs to be different at the DNA level. They share their source of DNA in common, but not the actual mix of the DNA components.  In conventional genetic evaluation, the assumption is that “on average” these full sibs will have 50% of their genes in common. In a Single Step BREEDPLAN evaluation, however, the actual proportion of genes in common is calculated and the true genomic relationships within the genotyped population are used to improve the accuracy of prediction of genetic merit.”