In this news, Intermizoo shares the press release from ANAFIBJ, published here, clarifying the situation regarding the new unwanted genetic conditions that the scientific community has highlighted in recent years: Muscle Weakness and BLIRD.

In recent months, the scientific community has identified two new undesirable genetic conditions in the Holstein Frisian breed.

These two defects are named:

  • Early Onset Muscle Weakness Syndrome (MW), initially also known as Calf Recumbency
  • BLIRD, acronym for Bovine Lymphocyte Intestinal Retention Defect

The National Holstein Frisian Breeders Association has decided that, starting from the end of February, the results of direct genetic tests will be reported on the official pedigrees and  freely accessible through the association’s online applications.

Intermizoo has also decided to adopt the national encoding in order to highlight carrier breeders. With the April evaluation update, the genetic profile of Intermizoo bulls can be directly consulted from the bull sheets: beneath the bull’s full name, the presence/absence of all undesirable genetic defects is indicated.

Regarding Calf Recumbency and BLIRD, here are the adopted codifications:

Calf Recumbency or Muscle Weakness (MW):

  • WF= Tested free
  • WC= Tested heterozygous carrier
  • WW= Tested portatore omozigote


  • LF= Tested free
  • LC= Tested heterozygous carrier
  • LS= Tested  homozygous carrier

As the number of undesirable genetic defects and haplotypes continues to rise, it has been decided to introduce the “HH Free” logo for those animals that are 100% free from known defects up to now.