A Rams Star rating may change after the genotype is included in the evaluation for the first time after testing. These changes occur as the extra information is added to the Rams stars based on the genomic result, which can move them up or down. On average, a Rams ranking will remain the same after testing; however, there can still be movements.
Attached below is a more detailed table of the probabilities of a rams ranking increasing after genotyping.
|Percentage increase in rankings||Probability|
|5% increase in rankings||42% chance|
|10% increase in rankings||30% chance|
|15% increase in rankings||24% chance|
|20% increase in rankings||16% chance|
|25% increase in rankings||11% chance|
|30% increase in rankings||7% chance|
Example 1, there is a 30% probability that after genotyping a ram would increase by 10% in the rankings.
Example 2, there is a 16% probability that after genotyping a ram would increase by 20% in the rankings.
Watch this video with a short explanation about it:
To summarise, small movements after genotyping are common, but the probability of large movements, such as moving from 1 Star to 5 stars, is less than 1%. Breeders will have to decide for themselves which animal they want to test for the scheme, with the full knowledge that some animal’s ratings will drop after testing, and some will increase. To maximise the number of scheme-eligible rams you will have to sell, you may want to consider doing a proportion of your 3 Star rams as well so that you don’t miss out on a sale.