A multinational team of experts has figured out why certain cows in a herd are affected by bovine digital dermatitis (BDD), a painful, contagious illness of the hoof that affects cattle worldwide, while others in the herd seem immune to it.
One of the most common illnesses affecting dairy cattle worldwide is BDD. The infection has an effect on animal welfare and is linked to infertility, mastitis, and decreased milk supply.
While various prevention measures used at farms have failed to appreciably curb the spread of the disease, treatment alternatives like topical antibiotics and chemical footbaths can cause bacterial resistance and harm the environment.
Bovine Digital Dermatitis affects dairy cows more
Daniel Quiceno M/Unsplash
Scientists from Germany's Martin Luther University Halle-Wittenberg (MLU) and the University of Göttingen teamed up with researchers from the University of Wisconsin-Madison in the US to conduct a detailed study to examine why some cows, usually from the same herds, does not suffer from BDD while others do.
They examined data from 5.040 genotyped animals and discovered that two gene mutations are the likely culprits causing cows to contract the disease.
The findings can be used in cattle breeding programs to breed disease-resistant animals and to develop a pre-screening test.
The German system for health trait evaluations in dairy cattle has already implemented the findings, DairyReporter highlighted.
Professor Hermann Swalve of MLU, one of the research's authors, noted that this was not their first publication or study on the genetics of claw disorders in cattle as they have spent a lot of work over the past 15 years researching the genetics of claw disorders.
He stated, "Digital dermatitis is a major problem on dairy farms all over the world. The disease is exceedingly unpleasant for the cows, and only very seldom would a farm be unaffected by it. From a tiny proportion to up to 80% of cows in every herd might be infected."
The study only took into account Holstein cows that were raised among 13 commercial herds in North Eastern Germany.
Following a visual examination of the animals using the M-scoring method, the researchers utilized DNA and sequence studies to determine why the afflicted cows were genetically prone to contract the disease.
The identification of two potential genes-CMPK2 and AS816-followed by further analysis revealed two minor gene alterations that were subsequently shown to affect disease susceptibility.
Due to the causative bacteria's ability to survive for up to a year without a host, the environment is crucial in the spread of digital dermatitis.
Cows kept in manure-filled conditions are more likely to contract germs.
These habitats are often damp, which results in an atmosphere devoid of oxygen and promotes the rapid growth of certain bacteria.
Manure builds up on the cow's lower legs, giving the germs time to combine and infect the feet. When cows have access to stalls, their hooves have more time to dry and are less exposed.
The occurrence of digital dermatitis is inversely correlated with how clean and dry the foot is kept.
A Wisconsin study showed that scraping three times a day was the minimum frequency needed to control infectious foot diseases, such as digital dermatitis.
Potentially, automatic scrapers maintain a cleaner lower limb cow than conventional scraping, but only if "operated continuously and over short distances".
If automatic scrapers are used across long distances, the cow is exposed to compounding waves of manure.
Due to cows being confined to concrete throughout the winter, which increases the stress on their feet, the prevalence of digital dermatitis tends to rise at this time.
The amount of manure deposited in the concrete area rises as less time is typically spent away from the concrete areas.
The cows stand in more dung throughout the winter if scraping frequencies are not altered.
As it decreases the number of accessible free stalls while increasing the amount of manure in the freestall area, overcrowding should be avoided.
Due to this situation, there is rivalry for a free stall.
Cows who are afraid to enter the stalls miss out and have more foot issues. Since the causative bacterium is disseminated by the increased presence of nervous cows, they make foot issues worse.
