Respiratory diseases are common ailments in calves. Hubert Pausch from the Chair of Animal Breeding at the Technical University of Munich in Germany and his team have traced a gene mutation in cattle responsible for it — a recessive mutation that alters the structure of the cilia of the airways. It only manifests in homozygous animals, where both parents were carriers of the mutation.

The altered structure affects the movement of the cilia, preventing the expulsion of sufficient amounts of secretion from the respiratory tract leading to infections. This mutation on chromosome 19 had already been discovered several years ago.

When reviewing the genome databases of cattle breeding associations, the team discovered that the mutation rarely occurred in homozygous animals. However, they found out that homozygous offspring died immediately after birth and was not included in the database.

So to clarify the cause of such high calf mortality, the scientists required information on homozygous calves not included in the database. They had to identify immediately after birth to be able to characterize them from a clinical perspective.

The scientists found twelve homozygous calves: five were stillborn, three died within 30 days, and four were taken to the cattle hospitals. These four were underweight and had chronic respiratory diseases. The animals had to be put to sleep after a few weeks due to their deteriorating health. The pathological examination showed changes in the structure of cilia inside their airways.

For more on this study, read the article at Technical University of Munich website.