Working with James Breen (Map of Ag and Nottingham University), they have explored how small changes in their cow management and environment can have a big impact on udder health.
Willow Tree extends to 162 hectares, growing a mixture of grass, winter wheat and maize. The herd consists of around 280 cows with an average yield of 12,600 litres. Cows are milked twice daily in a herringbone parlour, calve all year round, and are fully housed.
The effects of mastitis in a herd are far reaching; from cow welfare to profit margins, milk quality and sustainability. But by taking advantage of extensive milk recording data from Willow Tree, and using the AHDB Mastitis Control Plan, James has helped the team bring down the number of new clinical cases of mastitis occurring at Willow Tree in the past year.
“In some ways, mastitis control is simple,” says James. “The vast majority of cows can be cured during the dry period. The question is can you stop the cow getting reinfected again at some stage in the lactation cycle?”
Analysis of over 1000 herds that used the AHDB Mastitis Control Plan showed that less than 10% of those herds had predominantly contagious patterns of infection. “You do find contagious mastitis patterns, but they are far less common. Overwhelmingly the predominant infection pattern is likely to be environmental,” says James.
Data is key to identify infection patterns and creating a plan to tackle mastitis on any farm. “Milk recording data and clinical mastitis case information are vital for understanding the pattern of infection in your dairy herd,” says James. “If we’re going to get anywhere, we need that information about who is infected and who is not infected.”
By using the milk recording data from Willow Tree, James was able to identify trends in the herd. “The cows I am most interested in aren’t the ones with an exceptionally high cell count or which have been reported with several clinical cases already, but the ones where there is a new infection. For example, we might see a cow that has had a low cell count for the last three milk recordings, suddenly recording a high cell count. This is a new infection in lactation and can help us start to identify patterns, such as whether there is a seasonal bias.
“We can do the same with clinical mastitis events; if you have cows that are detected with clinical mastitis at less than 30 days in milk, the research evidence shows that they were already infected before they started lactation. So, this is likely to be a dry period infection. New clinical mastitis cases in cows that are more than 30 days in milk are likely to have been caused by infection in the milking cow environment.”
The clinical mastitis data from Willow Tree showed a clear trend. “We began by looking at clinical mastitis cases from April 2020 to April 2021,” says James. “The target for cows in the first month of lactation should be less than one new case in every 12 cows. This was easily being met by this herd.” The rate of new cases in cows more than 30 days in milk, however, was much higher, exceeding the target of two new cases in every 12 cows.
“Because the number of new cases appearing in the first month of lactation was so low, we can rule out the infection stemming from the dry cow yard or calving areas,” says James. “Instead, they are picking up the infection after joining the milking herd. So, the cause must be found in the milking cow environment.”
Finding a solution
Visiting the farm at the beginning of 2022, James spent time with Howard and Tom reviewing the farm set up to identify changes that could be made given what they already knew about the pattern of infection.
“We used to run the cows in three pods plus a high cell count group,” says Tom. “One of James’ first recommendations was to get rid of the high cell count group and open up the four barns to allow the herd to run together.”
James emphasised the importance of maximising the available living space to help manage infection. “Studies have demonstrated that increasing the living space available to each cow can be beneficial to both cow welfare and yield. This has been particularly important in managing mastitis at Willow Tree.
“The high cell count group enjoyed the most living space, while the rest of the herd was run at almost full stocking density. There was no evidence of contagious mastitis patterns, so it was a simple solution to open the space allowing better use to be made of passageways and loafing areas.”
The herd now have the run of all four sheds. “They pick and choose where they want to go,” says Tom. “But they like different sheds at different times of the year, which is something we will be looking at in the future.”
The type of sand used for bedding has been changed. “We test the sand for bacterial contamination,” says Tom, “but it is much softer and more free draining. We haven’t needed to dig the beds out at all in the past year, whereas previously we were digging them out every five to eight weeks.”
Howard and Tom have also made improvements to the collecting yard, increasing the available space. “We’re aiming for at least two square meters per cow in the collecting area. If cows are tightly spaced pre milking this can be a challenge for environmental mastitis infection control,” says James.
Finally, they considered the post milking yard and how cow flow could be improved. “We’ve allowed more space post milking,” says Tom. “While the cows are now run as a single group in the shed, we still milk them in two groups to help control pressure in these areas.”
Reaping the benefits.
The number of new infections continued to be monitored throughout 2022.
In 2021 the rate of new cases in cows that were more than 30 days in milk averaged at 4.5 cases per 12 cows. “Initially the rate of new cases fell throughout the first months of 2022,” says James. “It spiked a bit in June and later during the hot summer but since then the rate of new infections has consistently fallen.” In 2022 the average rate dropped to 3.5 new cases per 12 cows plus 30 days in milk, and for November 2022 to January 2023, the average was only 2.5 new cases per 12 cows.
“It’s rarely one thing that needs to change,” says James. “You usually need to make a combination of changes and might not know which is working the best, but as long as the rate of new disease is coming down, you’re making progress.”
Looking ahead
James is expecting that the rate of infection at Willow Tree might rise slightly in the summer with the heat.
“The cows are favouring certain parts of the shed at certain times,” says Tom. “We need to look at both temperature and airflow and how we can address this in the future.”
But the team are heartened by the fact that the overall infection rate is falling. “Ultimately the main change was very simple,” says James. “We focused on opening things up and giving the cows more living space, reducing opportunistic environmental infection immediately before milking, immediately after milking, and between milkings.”
