Individual data key to improving SCC (May 22)

Targeting the dry-cow period to reduce somatic cell counts in the following lactation has paid dividends for one AHDB strategic dairy unit. We spoke to the producer, and two vets, to find out more.


TEXT ALIX MORLEY



Cumbria-based producer Adrian Bland has been on a mission to reduce cell counts in his autumn-block-calving herd. And working with independent vet James Breen, as well as following the principles of AHDB’s QuarterPRO programme, Mr Bland has seen some remarkable results.


“We had a bit of a hike in our somatic cell count after calving in 2019,” says Mr Bland, whose unit at Ninezergh is also an AHDB Strategic Dairy Farm. “In 2020 it was even worse, which is why we wanted to solve the problem by 2021.”


To do this, gathering and understanding data is vital, according to Mr Breen, who adds that it’s important to start by examining the drivers of an increased bulk cell count. While bulk cell counts highlight the proportion of the herd that’s likely to be infected, the figures will also include uninfected, infected and chronically-infected cows. Individual-cow milk recording is, therefore, vital to understanding cell count infections in a herd and putting in place appropriate preventive measures


Monitor trends


“We need to be looking at this data, even if cell count isn’t an issue,” says Mr Breen, who divides his time between consultancy with Map of Ag and work at the University of Nottingham. “We can still monitor trends in new high-cell-count infections and, therefore, have an early-warning system in place. It is only through milk recording that it’s possible to take a step back, look at what is driving new infection rates, and begin to think about what should be done to prevent more new infections.”


Mr Breen says key questions to ask when reviewing your data should be: are more than 10% of cows being reported with more than 200,000 cells/ml at the first test day after calving; and are more than one in 12 cows being detected with clinical mastitis within 30 days after calving?


These are key markers for dry-period infection patterns. The predominant infection pattern in a herd can be identified using the mastitis pattern analysis tool, as part of AHDB’s QuarterPRO scheme. This highlights if a cow was already infected, what the infection pattern looks like and whether any changes in management have been successful.


In November 2020 Mr Bland began milk recording again, and to track the results of individual cows. Reviewing the data available, it was clear that the dry-cow period was an area that required attention. “If there are cows with SCCs of more than 200,000 cells/ml in their first milk recording post-calving, research shows these are likely to be infections the cow already had when she calved,” says Mr Breen.


Dry-cow management


“For the past five years we have used antibiotic dry-cow therapy across the herd. We’ve used sealants in the past but stopped in a bid to save money,” adds Mr Bland. His dry cows were rotationally grazed until three weeks before calving before being moved to a paddock for calving. But, because Mr Bland was also improving his fertility management, the calving block was becoming getting tighter and, as a result, the number of cows calving in the paddock at any one time was also increasing.


Working with the herd’s own vet, Andrew Crutchley from Yan Farm Health, Mr Breen and Mr Bland created a longer-term management plan that focused on dry-cow management, and aimed to reduce the risk of new infections.


Five key areas were identified. “Research around the effectiveness of internal teat sealants is strong,” says Mr Breen. “So Mr Bland began using this on all cows at drying off, with additional emphasis on a hygienic infusion technique. We also reviewed exactly what steps are required when drying off.”


Protocol review: scrupulous hygiene is required when drying off cows


After treatment, they also looked at the importance of environmental factors to support the control programme. This included ensuring that groups of dry cows spent no more than two weeks in any one area, improved bedding management for close-up dry cows, and optimising stocking density in the calving paddock.


The combination of dry-cow therapy and environmental management is vital, according to Mr Breen. “It’s no good us just focusing on using dry-cow therapy hygienically and using internal teat sealants but then not thinking about where they’re going to spend the next seven or eight weeks."


The trio developed a plan for the herd. “Because we were a high-cell-count herd, we set the threshold for antibiotic treatment quite low,” says Mr Bland. “Around 45% of the herd were given teat sealant only, and the remaining 65% also had antibiotics. The heifers were targeted slightly lower, so any heifer with a cell count greater than 120,000 in any of their final three milk recordings were given antibiotic dry-cow therapy. For the cows, we set this number at 150,000 cells/ml.”


When it came to addressing the environmental factors, Mr Bland had to get creative. With limited options, he re-purposed an existing building. “We built temporary cubicles within existing pens and laid rubber mats on the slats to house cows prior to calving,” he says. “Each pen housed eight cows. At the end of the building was a straw pen, and the building itself was next to the calving paddock. We fed dry-cow rolls, rather than a TMR, and bedded the cows and cleaned the cubicles daily.


“Any cow thought likely to calve in the next 24 to 48 hours was moved to the calving paddock. We were able to reduce the numbers in the calving paddock at any one time.”


Comparing data


“Comparing herd average data from October and November 2021 to the same period in 2020 shows that SCC is now much lower,” says Mr Breen. “Looking at the data from November 2021, the dry-cow period new infection rate is now zero. In other words, no cows dried off with a SCC below 200,000 cells/ml calved back in with a cell count more than 200,000 cells/ml.”


Those cows entering the drying-off period with an SCC above 200,000 cells/ml show a similar pattern. “Data shows that 87% of cows dried off with a SCC more than 200,000 cells/ml come back into the milk at below 200,000 cells/ml at their first test,” adds Mr Breen.


He stresses that prevention is key. “But it’s not simple. Where do the new infections come from? We tend to assume that new infections come from other infected cows. For some herds, contagious infection patterns are important. But for many herds it’s environmental infection.”


Mr Breen says control plans must also be targeted – one size does not fit all. “Each unit will have different pathogen profiles, milk yields and environmental management plans. Mastitis control is about looking at a herd’s data at this particular time and designing a small set of control measures that are going to have the greatest impact.”


Mr Bland admits that he was initially sceptical of some of Mr Breen’s suggestions, “But never in all my time milking cows have I seen bulk somatic cell counts in just double figures. But we saw that twice in November 2021 – at 67,000 cells/ml and 85,000 cells/ml. That’s the result of following the advice we were given.”

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