How to reduce mastitis ahead of spring calving

In spring-calving herds, environmental pressures of housing can create a greater risk of mastitis, with cows very susceptible to new infections a few weeks before they calve.

Losses from mastitis can cost about £400/case. As well as being a financial drain, it is a cow welfare issue, which is often underestimated.

More than 90% of cases are predominantly environmental pathogen infections.

So, it is well worth focusing on dry period management ahead of calving and reviewing practices to see where improvements can be made to reduce these.

See also: How to dry off cows to treat mastitis successfully

Analysing mastitis patterns for the previous season is a key starting point, says James Breen, a vet and associate professor in cattle health and reproduction at Nottingham University.

“The [most important] thing you can do for mastitis control is to calve down an uninfected cow. It is always more difficult to cure an infection when cows are milking.”

Most infected cows will cure with antibiotic dry-cow therapy, he adds. “With mastitis, you can wipe the slate clean during the dry-cow period.” He explains what data points to analyse.

1. When and what infections are occurring?

As a starting point, it is critical to establish when mastitis cases are happening on your farm – during lactation or during the dry period.

To understand this, you need cell count data from individual cows at least every six weeks (every month is best).

All cows in-milk should be present at milk recording, including those under treatment or with clinical mastitis.

Some block-calving herds may wait a few months until all cows have calved, but this leaves gaps in data.

If cows and heifers are grouped separately, review the data separately to help target management practices. Heifers are a good sentinel for infection because they generally do not receive dry-cow therapy.

2. What pathogens are causing mastitis outbreaks?

There are two types of pathogens:

• Environmental (for example, Streptococcus uberis and E coli)
• Contagious (for example, Staphylococcus aureus).

Bacteriology can help point to the right treatment plan, but is not very useful when trying to identify trends to prevent mastitis.

Always sample clinical cases – this tells you the pathogen profile cows are exposed to – but testing cows with high cell counts can be misleading.

“If you milk-sample high-cell-count cows that don’t have clinical signs, the recovery rate for pathogens is poorer. What you need to do is understand the infection pattern,” explains Dr Breen.

3. Record clinical cases

Record cows with clots/bits in their milk, irrespective of whether you treat that animal or not. Ideally, score cows according to the following grades:

• Grade 1: Clots/bits in her milk
• Grade 2: Hot and hard quarter
• Grade 3: Sick cow with severe clinical signs (raised temperature and loss of appetite).

If you milk-record with NMR, CIS or QMMS, you can fill out a form to request a summary of your mastitis patterns.

James Breen was speaking at a recent AHDB event at The Farm, Longnor, Shropshire

Case study: Tim and Louise Downes, The Farm, Longnor, Shropshire

Producing antibiotic-free milk means mastitis prevention is key for the Downeses.

They place great focus on cleanliness at drying-off and milk-record monthly so they can monitor infection and look for patterns in mastitis prevalence.

Louise and Tim Downes © MAG/Rhian Price

Cows are dried off 60 days before calving using surgical spirit, cotton wool and teat sealant only.

Heifers have also been given internal teat sealant for some time because Mr Downes says mastitis infection in heifers had become their Achilles’ heel.

Treatment

At the first sign of clinical mastitis, they will use udder mint, homeopathic remedies and fluids. Non-steroidal anti-inflammatory drugs (NSAIDs) are also used strategically.

“We assess if it has got worse or if we had one a week ago that should have had Metacam [NSAID],” explains Mr Downes.

He adds: “If any have clots or problems, we will wait until they are better before we dry them off. We wouldn’t dry off a cow that has clinical signs.”

Data

At The Farm, Longnor, the new infection rate during lactation (more than 30 days in milk (DIM) and above 200,000 cells/ml) was 4% in 2020, but this climbed to 7% in 2021 and 11% in 2023.

Another issue that milk recording data flagged up was that 20% of heifers, and one-third of cows that dried off with a low cell count at the end of 2021, calved in with a high cell count in 2022 (less than 30 DIM).

This infection will have originated in the dry period because these animals had cell counts above 200,000 cells/ml at their first milk recording, says James Breen, vet and associate professor in cattle health and reproduction at Nottingham University.

Peaks and troughs of infection during lactation will also be environmental, Dr Breen explains: “If you had a truly contagious and transmissive infection between cows, the new infection rate will always be high.”

The Downeses believe overcrowding in the dry cow shed on the back of a TB outbreak caused a larger proportion of cows to have high cell counts.

Higher infection in heifers was probably because not all of them received teat sealant. This was because later calvers had not bagged up enough for the sealant to be administered.

Improvements

Dr Breen assessed the data, and suggested ways in which the Downeses could make improvements:

• Cow space Heifers and cows are calved separately on straw yards, but space is a limiting factor. Cow space equates to 4.33sq m a cow and 6.6sq m a heifer, but the recommended allowance for dry cows is 1.25sq m for every 1,000 litres of milk. Therefore, it should be 7sq m a cow at The Farm.
• Bedding Cows are bedded daily and heifers every other day, and the shed is cleaned out twice during calving. An “easy win” would be increasing bedding and clean-out frequency to daily and weekly, respectively, as well as improving airflow in the cow shed.

“If you don’t use antibiotics at drying off, you must be even better at prevention, because you have a limited opportunity to cure cows,” he says.