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Eamon O’Connell: Forget about grass fever – an outbreak of mastitis can be devastating


Paying close attention to the milking parlour is essential to keeping on top of mastitis

Paying close attention to the milking parlour is essential to keeping on top of mastitis

Paying close attention to the milking parlour is essential to keeping on top of mastitis

Grass fever has arrived with a bang in north Tipperary.

A condition more contagious than Covid, it is spreading at a rapid rate. All it takes for a farmer to catch this disease is for him/her to see a neighbour’s field being mowed. Then the itch begins.

I met a contractor a few days ago and he said: “If only lads would cut fields that weren’t in view of the road, we wouldn’t have half as many looking to get it done this week.”

Thankfully, the prognosis for anyone with grass fever is quite good. Once the flurry of the few days are over, the only lasting side effects are a dented bank account and a sore back from covering the pit.

Another highly contagious condition that is starting to feature at the moment is mastitis. We have seen a sharp increase in enquiries and call-outs to cows with mastitis in the past two weeks. In suckler cows, its relatively uncomplicated and easy to see.

A visibly sick cow with a swollen quarter is a sight that many suckler farmers will be all too familiar with. Both cow and calf have to be brought back into the shed to allow easy treatment for a few days. Antibiotics and anti-inflammatories will be needed, but the cornerstone of treatment involves stripping out the offending quarter at least once a day.

I know you can be taking your life into your own hands doing this, so a good crush gate is necessary, along with a rope to tie the back legs to avoid a serious kick. Stripping out the quarter can get it back into milk after a few days if its picked up early enough.

If there is a delay in spotting the mastitis (often due to being busy at silage), stripping the quarter can be the difference between keeping a cow healthy and potentially losing the quarter altogether.

Prevention of mastitis in suckler cows involves primarily keeping flies away, as they are the main source of the infection and are excellent at spreading it to other cows.

There are a few pour-on products that are very effective along with other, less common but still useful, products such as fly tags, garlic licks and Stockholm tar. Despite using some, or all, of these products, cows will still get mastitis, so regular checking and early detection are vital for a good outcome.

Mastitis in dairy herds is, unfortunately, not as straight forward. Clinical mastitis is very easy to see in dairy cows: often, the first sign is in the milk sock — at the end of milking, creamy gunk is collected in the sock which alerts the milker that there is a problem cow. At the next milking, fore-stripping the cows will usually identify the culprit and the offending quarter. Mastitis tubes for three days and everything returns to normal. Simple? If only.

It is important, at this point, to emphasise the link between somatic cell count (SCC) and mastitis. I am regularly amazed at how many dairy farmers are unaware of the link between the two.

Somatic cells are natural immune cells that are always present in milk. They are mostly made up of white blood cells, which increase in response to the presence of bacteria that cause mastitis.

Every cow has an SCC which will fluctuate, depending on the level of bacteria in the udder. Sometimes, when bacteria start to multiply in a quarter, the white blood cells will win the battle. This would be visible as an increase and then a subsequent decrease in the individual cow’s SCC. It most likely wouldn’t be visible in the bulk milk tank reading.

Other times, it will take a bit more effort to clear the infection. Visibly, the cow will look fine, but her SCC will climb significantly and will take longer to come back down. For all intensive purposes, she has mastitis, despite the fact that it isn’t visible.

She is easily identifiable on a milk recording but, outside of that, will only be detected using a California Mastitis Test (CMT). We’ve all seen one of these — four paddles (one for each quarter) where the milk from a high SCC quarter changes colour and becomes gloopy when it reacts with a purple coloured liquid. A handy tool, but sometimes frustrating when the result isn’t fully apparent on a borderline case.

Often a cow can have an exceptionally high SCC for a prolonged period without showing signs of mastitis. These ‘millionaires’ have mastitis, you just can’t see it. An SCC of less than 100,000 means a cow has a healthy udder. Anything greater than that is a concern.

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Bulk tank SCC is a figure that is brushed over by many farmers. Many are happy with a figure of 200,000, or even higher: “Sure mine is always around that figure at this time of year.”

Let’s be honest now, a bulk tank SCC greater than 200,000 is a problem. It means that, regardless of herd size, there are a few cows with very high SCCs in the herd at present. They have mastitis — just because you can’t see it, doesn’t mean it’s not there.

So if your herd has a bulk tank SCC of greater than 200,000, what can you do? Well, you could ignore it and hope it doesn’t get higher. This is like ignoring the oil light flashing red on the dash of your car. Yes, it might get you home today, but some day soon, you’ll be stuck on the side of the road in the pouring rain, waiting for the tow truck. Your engine will have seized and your car will be goosed.

It’s a lot easier in the long run to address the problem head on. If the oil light starts flashing, you check the dip stick, top up the oil and get the car serviced.

A bulk tank SCC of 200,000 or more is the equivalent of the warning light flashing. It’s time to take action to prevent disaster. A full herd milk recording is the first step. This will identify the high SCC that have hidden mastitis. These can be treated or culled, depending on the cow.

Regular milk recording for the rest of the year is needed to monitor what cows are starting to creep up. A full service of your milking parlour is essential, including a change of liners if needed.

Similar to many health issues in dairy herds, the basics is where the game is won and lost — post-milking teat spraying, regular sampling for culture and sensitivity, along with the possibility of vaccination.

It’s time to turn your attention from the silage field to the milking parlour. 

Eamon O’Connell is a vet with Summerhill Vet Clinic, Nenagh, Co Tipperary

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