By studying the genetic origin of a recessive disease affecting the Holstein breed, a team from GIGA has discovered how this affects the fertility of these dairy cows. Up to the present time, early embryonic death of homozygous individuals could not be attributed to the impact of the mutation responsible for the brachyspina syndrome on fertility levels in bred cattle. This discovery has opened a new channel of research in the fight against the decrease in the fertility of cattle populations. 

Breeding involves reproduction, and the very essence of reproduction depends on the fertility of bred animals. High fertility, therefore, represents a major challenge for all types of breeding. The consequences of a drop in fertility levels are self-evident: a reduction in herd numbers and in stock farming products followed by inevitable negative economic and social impacts.

In the case of dairy cattle and more particularly the Holstein breed, the situation is particularly worrying. For decades, fertility in this breed which is the most widespread in the world has been steadily declining. Fertility, which can be estimated from a set of parameters such as the number of calves born, the calving interval (or the time neccessary for a cow to have two calves), the age at which the cow is culled, that is to say the moment when the farmer decides to stop using it for breeding purposes, and many other factors, is expressed in the form of an index. “This index combines all the criteria which are involved in measuring fertility and all of these criteria have diminished during recent decades”, explains Carole Charlier, senior research associate with the FNRS and project leader at the GIGA Unit of Animal Genomics.

In collaboration with the Merete Fredholm team from Denmark, Carole Charlier recently identified a mutation which partly explains the decrease in the fertility of Holstein dairy cows. The results of this study have been published in the journal PLoS ONE ⁽¹⁾.