Interpretive Summary: Genetic inbreeding depression load for fertility traits in Pura Raza Española mares
By Anne Zinn
A study published in the Journal of Animal Science analyzed the genetic parameters and the level of inbreeding depression for reproductive traits in mares of the Pura Raza Española horse breed. Additionally, it was estimated, for the first time, the inbreeding depression load associated with common ancestors of the breed.
Over the last few decades, fertility has been studied as a breeding goal in domestic species, but horses have historically been selected for conformation or performance in equestrian sports without much regard to fertility. For this reason, there is little information available on fertility traits and their inclusion as selection criteria in equine breeding programs.
Results of the present study demonstrate the importance of taking the potential inbreeding depression load into account for reproductive traits in order to improve reproductive fitness in the Pura Raza Española breed. Additionally, it was shown that the result of mating related animals to increase or decrease traits not only depends on their additive genetic value, but also on their partial inbreeding and the inbreeding depression load genetic values of the common ancestors. In fact, the results indicate that the inbreeding depression load values have a greater influence than additive genetic values on the fertility traits of inbred animals, when analyzing animals with a large Fij from a specific ancestor.
These are significant because understanding the individual inbreeding depression load genetic values of stallions and mares for a particular trait is of great interest to the Pura Raza Española Breeding Programme, where the detrimental or beneficial repercussions of alleles from certain lineages would allow breeders to make a better selection of breeding animals.
The full paper can be found on the Journal of Animal Science webpage.