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Working together to tackle mastitis

At the British Mastitis Conference, antimicrobials, dry cow therapy and teat sealants were highlighted as topics to discuss with farmers

12 December 2018, at 9:23a.m.

Delegates at the 2018 British Mastitis Conference included researchers, milking machine specialists and those with other commercial interests, as well as veterinary surgeons, who accounted for about a third of all delegates. Tackling mastitis involves a wide range of technical abilities.

The previous day attracted overseas delegates to a research update. As well as the presentations, there were 13 posters for delegates to view and the best poster award was judged, by the delegates, to be “Maximising milking efficiency: A pilot study of current UK parameters and factors affecting the milking process” by Advance Milking. The data were processed to calculate “milk per hour”, “cows per hour”, “milk per stall per hour”, “milk per milking unit per hour” and “milk per labour unit per hour”. There is poor correlation between the metrics indicating milking efficiency, and different metrics are suitable to assess different types of milking system. Milking efficiency was found to be positively associated with rotary parlours, mean cow yield and automatic cluster removal at flow rates greater than 300ml per minute.

Phil Elkins from Westpoint Farm Vets discussed strategies for reducing antimicrobial use with mastitis; although all agree that antimicrobial use should be rational and appropriate, he advised that care should be taken when introducing changes on-farm. Identifying the causal mastitis pattern and taking steps to reduce the mastitis rate will often see the best return on investment. Care is needed when implementing selective dry cow therapy, the use of rapid diagnostics and pathogen-based treatment protocols. The speaker highlighted the need for consistency in assessing antibiotic usage over time as different parameters give widely different figures.

Dry cow therapy or teat sealant?

The selection of cows to receive dry cow therapy, teat sealant or both requires careful consideration and discussion with the farmer. Criteria include the attitude of the farmer to risk and the application protocol will be particular to that herd and fluid over time as confidence in the procedures increases. Any cow whose teats cannot be effectively sterilised prior to infusion, due to teat end damage or low ground clearance for the udder, may need dry cow antibiotic plus teat sealant. Rapid diagnostic kits, with clinical cases, have a role in indicating whether gram positive or gram negative organisms are implicated but waiting for the kit result before starting treatment of afflicted quarters risks a reduced disease clearance.

There was discussion about the use of a single tube treatment immediately and then applying specific therapy when bacteriology results are available. It was highlighted by delegates that injection of anti-inflammatories is increasing as an alternative to antibiotics. The need to reduce the volume of antibiotics used for mastitis on-farm is clearly acceptable to farmers but the speaker indicated that achieving a reduction without increasing disease requires deliberate and accurate veterinary involvement.

Andrew Bradley, Director of Quality Milk Management Services and a professor at the University of Nottingham, described a study, involving over 800 cows from six low cell count herds, that investigated the value of dry cow therapy administered to quarters rather than cows. Not all the cows have calved, but the preliminary results indicate that the potential volume of dry cow antibiotic used would be halved with quarter selection. The speaker advised that a quarter therapy programme would not be applicable for high cell count herds.

In general, the use of antibiotic dry cow therapy in low cell count cows appears unjustified. However, high cell count cows with California Milk Test negative quarters could also receive teat sealant alone. The herds that could benefit from quarter targeted therapy have low levels of contagious mastitis. With the changes recorded on UK farms, it is recognised that 80 percent of cows in the average herd are not infected at drying off and should receive teat sealant to prevent new infections during the dry period. Of the remaining 20 percent that would receive antibiotic and teat sealant, quarters uninfected with pathogens, receiving teat sealant only, have achieved acceptable self-cure rates.

Pablo Silva Boloña from the University of Wisconsin outlined that half of new milking systems in the EU will be automatic. The number of milkings performed by a robot each day indicates dairy efficiency. A study to assess the effect of teatcup removal settings on milking efficiency and milk quality in a pasture-based automatic milking system measured 20, 30 and 50 percent of the average flow rate settings. The 30 and 50 percent settings showed no difference in somatic cell count and milk production but enabled three extra cows to be milked per day. The milking duration and time in the robot were reduced.

Katharine Leach, Research Assistant and Scientific Administrator at Quality Milk Management Services, raised the question: Do herd mastitis patterns change over time? A study of 66 herds from 2012 to 2017 indicated that not only did the mastitis change over the years, but nearly half of the herds showed differences between the past three months compared to the year. The contagious, environmental, dry period and lactation infections were identified. The epidemiological patterns suggest that the greatest influence on mastitis in the UK is the environment. A pattern analysis tool (PAT) is available online from AHDB Dairy that enables rapid herd mastitis pattern analysis.

Rachel Hayton, a veterinarian at Synergy Farm Health, and Daniel Macey, Director at Underhill Farm, described the actions taken to overcome the high mastitis incidence in a Somerset dairy herd. In less than a year the clinical mastitis rate has fallen from 83 cases/100 cows/year to 39. Lactating cow tube usage has fallen from 3.90 standard courses per animal (DCDVet) to 0.66 and the farm is no longer in the top 10 percent of antibiotic users in the practice.

Data analysis led to a diagnosis of environmental mastitis of predominantly dry period origin. A reduction in costs associated with clinical mastitis of £36,000 was demonstrated and veterinary costs have fallen from a peak of £6,000 per month to £2,000, where product charges have been replaced by consultancy. Management of the environment has been improved, with greater attention to detail, together with consistency of milking routines. Applying the AHDB Dairy Mastitis Control Plan has proven the value of the analysis and application of the various elements.

Teat coverage with disinfectant is an important element of the control plan and Brian Pocknee, Senior Dairy Husbandry Consultant at The Dairy Group, explained the findings of three studies to assess dipping, handheld spraying and a platform-mounted automatic system.

Teat dipping was shown to be the gold standard against which other systems should be judged, with 97 percent coverage of the teat barrel, 100 percent coverage of the teat end and a chemical volume of 10ml per teat. Manual spraying achieved 50 percent barrel and 95 percent teat end coverage with 15ml per teat. The attention of the staff using the lance is essential; 10 percent of front teats were missed altogether. The automated system achieved similar coverage to dipping but chemical usage varied from 18 to 60ml per teat. Work is ongoing to achieve equivalent results with reduced chemical use.

An update on current teat disinfectants was presented by Mario Lopez, Technology Manager at DeLaval, who discussed germicidal components, emollients and surfactant elements. A teat disinfectant should have enough contact time to kill the microorganisms on the skin; the surfactant helps to remove soiling from dirty teats and the emollient has to cover as much of the teat as possible to maintain a healthy and soft skin. Manufacturers are very aware of regulatory and consumer concerns regarding the risk of chemical contamination of the milk, particularly with pre-dipping. Correct use of products is important to achieve effective disease control and clean milking.

Copies of the proceedings are available from The Dairy Group (bmc@thedairygroup.co.uk) and proceedings from earlier conferences can be downloaded at britishmastitisconference.org.uk. Veterinary surgeons are invited to suggest topics that they would wish to be included in the 2019 conference.