22 March 2021
Counting down with mastitis
19 February 2021
When 12-year-old Ruby White steps off the school bus at the end of the day, it’s not chilling out or homework that’s on her mind.
Instead Ruby heads to the dairy to help mum Tania milk the herd of 170 cows, each of which Ruby knows by name.
“Ruby is my right-hand helper in the shed; she just loves milking and being with the animals,” Tania says who, as a successful dairy farmer, is indisputably also her daughter’s role model.
The shy youngster, who attends St Joseph’s School in Te Aroha has an ambition to follow her mother into farming but her view of the career is not through rose-tinted glasses. She knows the truth of the old adage “when you have livestock, you have dead stock too”.
“I love spending time with the cows,” Ruby says, as she hugs “Babe” in the paddock.
“Ruby understands that this is a business and that while we care for our cows, they are not pets,” says Tania.
Dairy farming is definitely in Ruby and Tania’s genes. Tania’s parents, Graham and Glenys Bell, are dairy farming close by at Waihou near Te Aroha, and Graham can trace his farming lineage back at least two generations.
Not only has the family been farming for a long time, but they also do it extremely well. Graham and Glenys have for many years had the lowest BMSCC (Bulk Milk Somatic Cell Count) results of any Fonterra supplier, and Tania, the second lowest.
It was for Tania’s impressive results that she was asked to host the SMASH (Smaller Milk and Supply Herds) field day in November when the focus was on being grade-free, on flexible milking and on summer feed management.
Steve Cranefield, technical manager with AgriHealth of Auckland, led the discussion on mastitis management for the 50 farmers who attended the field day, bringing Tania and her father Graham into the discussion to explain their strategies for achieving such consistently low cell counts.
Tania’s BMSCC results were 31,180 cells/ml in 2019/20, the second lowest for a Fonterra supplier. While achieving low counts is important, Tania and Graham said that was not the prime focus of their management system. Healthy, happy cows are what they strive for and low somatic cell counts are a consequence of that policy.
Tania is an AB technician for LIC, a role she has carried out for the past 25 years, alongside sharemilking. Three years ago, she moved from sharemilking at Te Awamutu to become the sharemilker on the 49-hectare farm owned by Jane Mellow, whose family links with that land go back nearly 100 years.
There Tania runs 170 cows mostly pasture-fed, with some maize for autumn feed and palm kernel for spring. The property, largely flat, has 3ha of chicory.
Tania’s approach to mastitis is one of prevention. She uses both the antibiotic dry cow treatment and Teatseal, the non-antibiotic inert substance that forms a plug in the teat canal, to prevent mastitis throughout the dry period and at calving.
“We pick up cows and calves twice a day. Any cow we have concerns about is brought into the shed and tested for mastitis. Any cow reacting badly will be treated, but anything that is a little bit iffy will be watched and checked at every milking. Generally, the quicker you treat cows the better the recovery. It’s all about knowing your cows,” she told those attending the field day.
Graham said both he and Tania had a policy of calving cows on grass. “We always calve on clean grass handy to the shed. We note cows that have had mastitis before and bring them in earlier before calving to keep an eye on them.”
Both farmers use the Rapid Mastitis Test (RMT), which is a “cowside” test to quickly identify cows with high somatic cell counts.
“Before we touch the cows, we teat spray them and we teat spray the colostrum cows before milking,” Tania said.
Steve said there is an industry push to encourage farmers not to use the dry cow antibiotic and rely on teat seal alone.
“I’m not willing to get into that debate, but here we have top farmers with the lowest cell counts, still using that combination and setting themselves up well.
“Graham and Tania only treat cows which have a good reaction [to the RMT test] and check on anything else. They have a good memory of how a cow was from one stage to the next and are looking for change.”
A new on-farm testing device called Mastatest helps take the guesswork out of treating mastitis, Steve said. “It’s easy to operate; just fill the cartridge with a mastitis milk sample and place it in the machine. Within 24 hours it tells the farmer which bacteria is causing the infection and the antibiotic most likely to work.” Farmer’s using Mastatest said they liked knowing what they were treating and that they used fewer antibiotics and got better cure rates when antibiotics were needed.
In response to a question about the antibiotic use, Graham said on his farm, “we use quite a lot during calving but throughout milking, not a lot at all”.
Another farmer asked why farmers should bother about somatic cell counts as Fonterra did not pay extra for low counts. “Cows produce way better when they are all healthy and ready to go when milking starts. We don’t set out to achieve low cell counts, we like our cows and want them to be healthy,” Graham replied.
Steve urged farmers to make the time to pick up cows and calves twice a day. “The more attention you give to the colostrum mob, the better the turnout. Getting cows and calves in early also means milking earlier.”
He also advocated the use of teat spray when stripping and milking colostrum cows, something routinely done on Tania and Graham’s farms. “There is an element of killing bugs, but it’s more about teat condition and cow comfort. A newly calved cow is likely to have dry skin in the udder and teat spray makes the first milking more comfortable.” Graham’s advice is to cover the whole udder when teat spraying.
Steve said healthy teats are the common denominator he has observed among low cell count herds. “If you want to know why you have mastitis in your herd, look at the cows and they will tell you why.”
The handout he gave farmers said: “If you assess your cows’ teats once a month you can learn why there is mastitis in the herd and monitor the results for change. Farmers are encouraged to assess 50 cows for teat skin condition and teat end damage once a month throughout the season as an early indicator of problems.
The targets are: teat skin conditions >95% supple; teat end damage >90% normal.
If any of these risk factors are lower than the target, then farmers should look to rectify possible causes or seek expert advice to avoid mastitis.
The industry’s understanding of mastitis management is evolving and there is increasing pressure on the farming community to reduce the use of antibiotics. Steve’s handout said efficient milking routines can help reduce mastitis.
Culling long-term infected cows is part of that management, as is drying off strategies. Steve recommends that cows with ISCC (Individual Somatic Cell Count) of <150,000 cells/ml and heifers with ISCC of <120,000 cells/ml can be regarded as uninfected and new infections can be prevented with teat sealant, although strict hygiene is critical when it is administered.
Routine stripping of the herd, (a quarter at every milking) will identify infected cows quicker and minimise the spread of infection.
Ensuring cows have good teat condition all year round is also important. Bacteria from milking an infected cow will contaminate the milking cluster for the next five cows that are milked. Teat spray trials in New Zealand and overseas all show a 50% reduction in the new infection rate if teat spray is mixed and applied correctly.
Healthy teat skin has a fatty acid layer that slows bacteria growth, reducing the mastitis risk. If teat skin is dry, the fatty acid layer is lost, and bacteria will multiply in the cracked skin. Good teat condition requires the addition of sufficient emollient and ensuring full coverage of all teat surfaces at every milking all season. Pre-milking teat spraying the colostrum cows will assist to improve milk let-down, improve teat condition, and reduce bacteria on the teats. Teat end damage from the physical action of the milking machine allows bacteria to grow and enter the teat canal. Adopting efficient milking routines will help reduce the mastitis risk from teat-end damage caused by overmilking.
MaxT (maximum milking time) is a strategy which defers residual milk to the next milking where it can be harvested more efficiently. Cows are milked to a predetermined end point – either to a fixed point or to a set milk flow rate threshold, whichever comes first.
Using the fixed time point, the idea is to estimate when about 80 % of the cows would have completed milking and remove the cup clusters from the remaining 20%.
Research shows the implementation of MaxT can increase the number of cows milked each hour in many New Zealand dairies, with no loss of milk yield and no increase in mastitis or somatic cell count. MaxT’s principles are based on harnessing basic cow physiology. (Source: Mastitis management and milking efficiency go hand in hand – Steve Cranefield BVS, www.agrihealth.co.nz)