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Data determines success in disease control (May 24)

A team approach is keeping tabs on disease data and ensuring that herd health ‘heads north’ and infection levels ‘head south’ on one Shropshirebased dairy unit.


TEXT KAREN WRIGHT



Shropshire-based producer Julian Evans works closely with his herd vet Sean Hughes to keep infectious disease under control and levels heading in the right direction – downwards.


And despite minimal issues in the 174-cow autumn-block calved crossbred herd, the pair are committed to routine screening for key diseases, such as Johne’s and BVD, with milk tests and tissue samples being key tools in their kit.


Julian is the second generation of his family to run the dairy herd, plus 125 followers, at Heath View Farm, near Shrewsbury. Their crossbreeding programme has been tweaked during the past 24 years to best suit their system and Julian is now settled on a Holstein Norwegian cross. They tried using a few ‘heavier’ breeds as a third cross with limited success, particularly in terms of fertility performance, which is crucial in a block-calving system.


“Our cattle suit our system, which is quite straightforward and not overly complicated,” says Julian. Herd average yield is 8,700kg, at 4.45% butterfat and 3.50% protein, with a combined fat and protein production of 700kg on twice-a-day milking.


Great store is placed on maximising milk from forage which is currently 4,500 litres. This includes homegrown grass – for grazing and silage – and maize grown on contract. Fodder beet is added to the TMR, and a summer buffer, which comprises maize silage and straw, is fed at grazing.


Block calving


“We calve in a 10-week block from mid-August with cows housed from late September and fed on a flat rate TMR, which includes a blend, C16 fat, minerals and limestone flour. No concentrate is fed in the parlour,” says Julian.


Turnout is typically by mid-March, but was delayed until after first cut, at the end of April, in 2024. Having a fit and healthy herd is fundamental to the dairy business’ success. Julian has no regrets that he’s taken a long-term view to recording cow performance.


“I’ve always kept a tight rein on monitoring progress – well before it was a requirement. But now we must have accurate records to meet our milk buyers’ contract criteria,” he adds.


“Thirty years’ of milk recording has helped us get where we are today with somatic cell counts, for example.” The herd’s current average somatic cell count (SCC) of 60,000 cells/ml and an average Bactoscan of 8 attracts praise from vet Sean when he reviews the herd’s records, particularly in light of the wet winter.


A long-term view is also taken to controlling Johne’s in the herd. Julian has screened for this infectious disease since 2016, using NMR’s quarterly milk-testing service HerdWise. Although levels were never high, they’ve gradually reduced to a current average test value (ATV) of 5.2, placing the herd in the best quartile nationally.


“The latest records show that 99% of cows are ‘green’ J0 or J1, so infection levels are extremely low. Our remaining red J5 cows left the herd in summer 2023.”


Healthy herd: cows are regularly screened for Johne's disease


Johne’s screening


The milking herd is Johne’s screened four times a year: in October and November, and then once in spring and again just prior to drying off. These testing months are tailored to the block-calving system, rather than following the traditional quarterly testing pattern. “Screening before breeding is vital to ensure we don’t breed replacements from any infected cows,” says Julian.


“If we do breed from them, we’ll use beef sires and mate them towards the end of the block so there’s no risk of infecting any heifer calves. This is part of our Johne’s plan, and it has really helped me manage the disease in the herd.”


Despite extremely low levels of Johne’s, Julian and Sean both know the importance of routine screening for the disease. The same goes for BVD. Although the herd is vaccinated and free from BVD, Sean knows that just one animal could slip through the net and, by using tag-andtest for all calves, any infected animal can be picked up quickly and early before further disease spread.


“Without regular NMR somatic cell counts, Johne’s screening and BVD tag-and-test data the herd would not have its high-health status and be confident in meeting its Arla CARE requirements,” adds Sean.


“We’d have no idea if good progress was being made,” he says. “This is a healthy herd and disease infection rates were never high, but screening keeps a check on trends and progress.”


More recently, improved monitoring tools have made control even more precise. For example, the Johne’s Progress Tracker introduced in 2021 compares the herd’s data with benchmarks recognised as having a significant impact on Johne’s infection rates.


“We can see where we’re going with this and the specific areas where most progress can be made,” explains Sean. “We use this tracker in the herd’s Johne’s review so we can home in on areas to make the best progress. I think we could have made quicker progress if infected cows were culled sooner, but this is only because very few other areas show up as weak links.”


This tracker is a big leap forward from the early days of Johne’s control where producers were encouraged to use the 30-cow screen to assess their herds’ infection levels.


“A 30-cow screen gave a rough idea of infection levels, but infected cows could be missed for a few years, and by then they could have infected many others, particularly their own and other youngstock,” he adds.


Controlling disease


Controlling infectious disease requires a team approach, but it is data driven. Shropshire Farm Vets finds this much easier now they can follow progress remotely and check each herd’s test results and disease status on the vet version of NMR’s Herd Companion.


“We do this for all herds on NMR,” says Sean. “We can download milk records and fertility information, as well as disease test results such as the HerdWise Johne’s screening data and BVD test results.


“It’s important to see what’s going on across the herd and not just focus on one aspect in isolation. Fertility, milk quality, somatic cell counts, and disease incidence are all part of the picture in when managing dairy herd health.”


He adds that this is made easy with Herd Companion. “It’s user-friendly and not too ‘figure heavy’. A quick glance highlights trends and then we can delve into specific areas. Each farm is different, but there’s always scope for improvement, and there’s never room for complacency when it comes to infectious disease control in dairy herds.”

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