Longlands Project Update - Controlling Mastitis: Importance of analysing mastitis pattern
Through their work as a Farming Connect focus site, Longlands farm has been working with Dr James Breen (Nottingham University and the Evidence Group) to reduce mastitis in the herd. Up to September 2018, the 12-month somatic cell count (SCC) was increased to an average of 263,000 cells/ml (target of less than 200,00 cells/ml). Dr Breen introduced the farm to the AHDB Dairy National Mastitis Control Plan as well as the new AHDB mastitis control herd pattern analysis tool. A detailed survey of the farm was undertaken along with analysing milk bacteriology, disease patterns, somatic cell count data and clinical mastitis information which was readily available through monthly milk recording data and on farm data. The AHDB mastitis control herd pattern analysis tool provided a fully automated method of assessing the main mastitis infection patterns on-farm. From the analysis, the farm is given a plan to combat mastitis with the aim being to reduce new clinical mastitis cases, SCC and subsequent antibiotic use across the milking herd.
There was no evidence from individual cow SCC that contagious transmission had a role in the mastitis pattern, therefore the issue came from environment management. The dry period can be less well managed on many dairy farms, yet dry period management is at least as crucial as the lactation when aiming to reduce mastitis incidence in the herd. The herd pattern analysis tool showed that new high SCC did not develop during lactation, but rather during the dry period as the dry period new infection rate averaged 21% (target of 10%). Analysis, therefore, suggested that mastitis at Longlands farm is mostly influenced by the dry cow management, of which Dr Breen reviewed and put forward the following recommendations:
- Providing clean and dry straw into the close to calving yard at least once daily
- Cleaning out the straw yard completely at least once a month
- Scraping dry cow alleyways, loafing and feed areas twice daily
- Reviewing drying-off procedure to include surgical spirit and cotton wool swab.
Housing design and system can affect the health and welfare of the cows, influencing diseases such as lameness and mastitis. Close to calving cows kept in loose yards with inadequate bedded area per cow are more likely to develop mastitis infection. Crowded conditions, poor ventilation and high humidity also increases mastitis infection risk, therefore, at Longlands, they adapted the dry cow shed to allow at least 2m2 bedded area per cow. If space is limited, transition cows should be prioritised and clean bedding frequency increased.
Dr James Breen reviewed the drying-off procedure with John, looking at the hygiene and technique, and incorporating cotton wool and surgical spirit at drying off. A regulated approach to administrating dry cow therapy influences the risk of new infection around drying-off. It is essential to clean the teats prior to drying-off with a pre-milking teat disinfectant and cotton wool soaked in surgical spirit whether you are using antibiotic dry cow therapy with teat sealant, or teat sealant alone. For consistency, all cows are now dried-off by John which will ensure consistency in a selective approach to antibiotic dry-cow therapy.
Positive results were seen following these changes in management, as the overall dry period new infection rate reduced to an average of 17.6% up to September 2019 (down from 21% at the start of the project). The reduction in new infections in cows was more dramatic, dropping below 10% through winter – but new infections in first calving heifers still proved problematic to control. The reduction in dry period new infections and improvements in dry cow therapy infusion technique, brought an increase in the dry period cure rate, (proportion of cows that move from more than 200,000 cells/ml to less than 200,000 cells/ml between drying off and post-calving) to 80%, up from 69.1%. Another key outcome was fewer clinical cases that occur in the first 30 days post-calving which reduced from more than 1 case per 12 cows during 2018 and early 2019 to less than 1 case per 12 cows in the latter half of 2019 (see Figure 1). Despite some improvement, the farm continues to discuss the lack of space that is not bedded area in the dry and calving yard as well as management of freshly calved cows and access to the early lactation cow deep sand cubicles rather than the loose yard ‘hospital’ group.
There is increased pressure to reduce antibiotic usage in dairy production and mastitis is a major contributor to overall herd use of antibiotic. By using selective dry cow therapy and improving management, there was a reduction of 13.57mg/PCU of total antibiotic usage between the 2018 and 2019 records at Longlands, which came under RUMA 2020 target of 21mg/PCU. The number of antibiotic tubes that were needed to treat clinical and subclinical mastitis significantly reduced from 7.29 to 4.34 daily doses.
The overall improvement in dry period origin mastitis infection is seen when herd data is taken to the end of January 2020 and submit this to the AHDB Dairy Mastitis Pattern Analysis Tool. Data for the last three months on individual cow SCC and cases of clinical mastitis show the overall reduction in the contribution from dry cow environment infection to the herd mastitis pattern. Following the reduced dry period origin infection, the current focus would now suggest a switch to thinking about control of new environmental infection of lactating period origin. Longlands remain focused on implementing the Mastitis Control Plan and monitoring cell count and mastitis data.
Figure 1. Dry period origin clinical mastitis rate (TotalVet (QMMS Ltd, SUM-IT Software)