What is a breeding value?
A breeding value expresses a horse's genetic potential for a certain trait and helps estimate what predispositions it can pass on to its offspring. It does not only evaluate the horse itself but uses information about its relatives, offspring, sports performance, and other available data.
Breeding values represent one of the most important tools in modern breeding and allow breeders to make informed decisions when selecting stallions and broodmares.
What does a breeding value express?
A breeding value does not answer the question: How good is this horse?
But rather the question: What genetic predispositions can this horse pass on to its offspring?
Two horses may achieve similar sports performance, but their ability to pass on performance to future generations can be significantly different.
How are breeding values calculated?
The calculation uses information from the entire population:
the horse's own performance,
results of relatives,
results of offspring,
pedigree and lineage,
data on environment and performance conditions,
genomic information obtained from DNA, if applicable.
Modern statistical methods allow separating the influence of genetics from the influence of the environment and obtaining the most accurate estimate of an individual's genetic value.
How to read breeding values?
Breeding values are standardized so that the population average corresponds to a value of 100. The spread of values is expressed using a standard deviation of 20 points.
This means that most horses in the population range from 80 to 120 points, i.e., within one standard deviation from the population average.
Indicative interpretation
less than 60 – below average
60–80 – weaker average
80–120 – population average
120–140 – better above average
140 and more – elite genetic level
Values in the range of 80–120 are the most common in the population and represent the usual genetic potential for the observed trait.
Conversely, values above 140 occur only in a small part of the population and indicate individuals with exceptionally favorable genetic predispositions.
When interpreting breeding values, it is always important to also consider the reliability of the estimate.
Example
Horse A has a jumping breeding value of 125.
Horse B has a jumping breeding value of 100.
Horse A is in the better above-average category, while horse B corresponds to the population average. This means that Horse A has a higher genetic predisposition to pass on jumping performance to its offspring.
However, this does not automatically mean that every one of its offspring will be a better jumper. The breeding value expresses the probable genetic contribution within the entire population.
What is the reliability of a breeding value?
Reliability indicates how accurate the breeding value estimate is.
up to 50% – preliminary estimate
50–70% – medium accuracy
70–90% – high accuracy
over 90% – very high accuracy
Young horses without offspring usually have lower reliability, while older stallions with numerous offspring achieve significantly higher reliability.
Low reliability does not mean that the breeding value is poor. It only means that the estimate is currently based on a smaller amount of information and can be refined further as more data becomes available.
Conversely, high reliability indicates that a larger amount of data was used in the calculation, such as offspring results or extensive information about relatives.
Breeding value is not a sports result
Breeding values do not replace information about sports performance.
When selecting a stallion, it is advisable to consider:
sports results,
conformation,
temperament and health,
pedigree,
breeding values,
reliability of the estimate.
The breeder achieves the best results when combining all available information.
The future of breeding
With the development of genomics and DNA analysis, it is now possible to estimate the genetic potential of horses at a young age.
Genomic information may complement traditional breeding values in the future and contribute to more accurate genetic evaluation of sport horses. However, their benefit primarily depends on the size and quality of the reference population.
Glossary of terms
Breeding value – an estimate of the genetic potential that a horse can pass on to its offspring.
Genetic potential – a set of hereditary predispositions for a certain trait.
Reliability of breeding value – data expressing the accuracy of the breeding value estimate.
Pedigree – a record of a horse's ancestors used in genetic evaluation.
Genomic information – data obtained from DNA that can complement classical genetic evaluation.
Genetic value – a technical term denoting the estimated hereditary contribution of an individual for a certain trait.