Dry cow management was top of the agenda at last week’s Large Herd Seminar, Woodbury, Devon, organised by Lillico Attlee.
Mastitis could have severe negative implications on cow fertility rates, said vet Matthew Burge of Coombefield Vets, Axminster.
But recognising the type of infection could allow farmers to make informed management decisions.
“The fact is non-pregnant cows that get mastitis are less likely to get in calf.”
“We all know mastitis and fertility are among the biggest problems facing dairy herd performance, but there has been little work on the links between the two.”
At calving, cows had reduced immunity, making them more susceptible to infection.
When a cow was exposed to an infection such as mastitis, white blood cells released inflammatory substances into the body as a defence mechanism. But these substances could be toxic to the developing embryo, increase the likelihood of cysts and raise body temperature.
The stage at which mastitis occurred and the severity of infection both influenced how fertility was affected.
“A mastitis infection before first service will increase the time to service by an average 14 days and add an average of 21 days to a cow’s calving interval.”
And a mastitis infection between first service and conception would add an average 57 days to a cow’s calving interval and require an extra 1.3 inseminations to conception.
“This hidden effect on fertility has severe financial implications when you consider the associated cost of about £4 a day open,” he said.
Mastitis needed to be a certain severity to cause release of inflammatory substances.
The more severe the mastitis infection, the greater the likelihood of fertility issues. “Cows just showing milk clots are unlikely to be affected fertility wise,” he said.
This in itself could allow farmers to make informed management decision, depending on mastitis severity.
“When a cow has a swollen udder or raised body temperature, it may be worth using cheaper semen or holding off service until she has recovered – it is worth having this conversation with your vet.”
There was also more justification in early use of non-steroidal, anti-inflammatory drugs to reduce the production of inflammatory substances in these cows – particularly in non-pregnant or early pregnant animals.
The key was early detection and aggressive treatment of mastitis in non-pregnant or early pregnant cows.