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Sealant of approval?

Research at Teagasc is aiming to identify and provide recommendations to farmers on using teat sealant alone at dry-off in uninfected cows. This will help reduce antibiotic use in dairy farms without negative impact on udder health.

TResearch Autumn 2023

Infusing cows’ teats with intramammary antibiotics at dry-off has been a common practice to cure existing infections and to prevent new infection over the dry period. The dry period and calving period are when cows are most at risk of new intramammary infections. However, regulation on veterinary medicinal products by the European Union states that antibiotics should not be used as a preventive measure. Therefore, it is no longer justifiable to treat cows with antibiotics at dry-off to prevent infections in the dry period.

An alternative is selective dry cow therapy. This involves treating uninfected cows at dry-off with an internal teat sealant, an inorganic product that acts as a physical barrier preventing the entrance of bacteria to the gland.

Infections are indicated by a measure of somatic cell count (SCC), with the common cut-off point being <200,000 cells/mL for uninfected cows, explains Research Officer Pablo Silva Boloña.

“International research has shown no difference in the prevention of new dry period infections in uninfected, low SCC cows treated with an antibiotic plus internal teat sealant or with a sealant alone,” he says. “However, Teagasc research found that cows with a SCC of <200,000 cells/mL treated with an internal teat sealant alone had higher SCC and infection levels in the following lactation compared to cows treated with antibiotic plus sealant.”

Pablo further explains that most infections were caused by Staphylococcus aureus, which differs from international production systems. Therefore, treating cows with an internal teat sealant alone is a challenge as some farmers might see this practice resulting in higher infection levels and SCC.  

Factors linked with reduced SCC

To address this situation, Teagasc has conducted studies in 21 commercial herds, using dry cow treatment, milk recording and bacterial infection data from >2,000 cows to identify factors that can help implement selective dry cow therapy with reduced risk to udder health. The team found that the following factors at dry-off and the dry period were associated with reduced SCC in the following lactation:

  • Milk yield and dry cow treatment: There was no difference found in SCC at the beginning of the next lactation between internal teat sealant alone or antibiotic plus internal teat sealant treated cows, when their milk yield at the last milk recording (30 days before dry-off) was ≤15 kg.
  • SCC at the last milk recording of the previous lactation: Cows with lower SCC at the end of their lactation were also likely to have a low SCC at the beginning of the following lactation. Cows with an SCC of 50,000 cells/mL at the end of their lactation had an estimated 60,000 cells/mL (± 30,000) lower SCC in the following lactation compared to cows with an SCC of 150,000 cells/mL.
  • Cleaning cubicles: Farmers that cleaned and disinfected cubicles twice per day had an estimated 40,000 cells/mL lower SCC cows compared to farmers doing it just once a day during the dry period and beginning of lactation.
  • California Mastitis Test (CMT): This helps farmers identify subclinical infections (i.e. no visible signs) in cows. Farmers that regularly used the CMT to identify their high SCC cows had lower SCC cows (estimated 7,000 cells/mL lower) compared to farmers not using it.

The importance of recording

A previous study showed that the best information to predict infection in late lactation was the SCC at the last milk recording of the lactation. “If farmers are not milk recording, they should start by doing one in late lactation to guide dry cow therapy decisions,” explains Pablo. “However, we encourage farmers to do multiple milk recordings throughout the year, as it is a helpful tool to manage mastitis.”

The researchers also explored the SCC cut-off point that improved detection of infection in late lactation. The quarter-level SCC that maximised the correct classification of both infected and uninfected cows was 61,000 cells/mL for first lactation cows and 100,000 cells/mL for ≥2 lactation cows. However, the cut-off point for ≥2 lactation cows was less accurate in classifying both infected and uninfected cows, meaning that using any cut-off point will result in a higher error in correctly classifying ≥2 lactation cows as infected or uninfected compared to first lactation cows.

Pablo explains that there’s no clear-cut solution to adjusting SCC cut-off: “By lowering the SCC cut-off point, farmers could detect and treat more of their truly infected cows; however, they will be unnecessarily using antibiotics on more uninfected cows,” he says. “Conversely, by increasing the SCC cut-off, farmers could be missing the opportunity to treat more of their infected cows, but would reduce their antibiotic use.” For now, the team has a set of concrete recommendations which can help farmers in their decision. 

> means greater than

≥ means greater than or equal to

< means less than

≤ means less than or equal to

± means plus-minus


  • Farmers should use their milk recording information to make dry cow therapy decisions.
  • Internal teat sealant alone should be considered if SCC is ≤61,000 cells/mL in first lactation cows and at least ≤100,000 cells/mL in ≥2 lactation cows.
  • If treating with teat sealant alone, implement measures to reduce milk yield to ≤15 kg/day near dry-off.
  • Do not look at an increase in SCC in late lactation as normal. This is due to increased infections and will affect the cows’ SCC in the following lactation.
  • Clean cubicles twice per day during the dry period and early lactation.
  • Use the CMT to detect high-SCC cows and quarters and take action when identified (treat, dry, cull).
  • Infections with Staphylococcus aureus need to be reduced to improve the outcome of selective dry cow therapy.


Funding from Dairy Research Ireland is gratefully acknowledged.


Pablo Silva Boloña, Research Officer, Animal and Grassland Research and Innovation Programme, Teagasc Moorepark. Email: silvabolona@teagasc.ie


The study team Clare Clabby, Pat Dillon and Ainhoa Valldecabres are gratefully acknowledged for their contribution to the research.

[pic caption] Treating uninfected cows with internal teat sealant may help reduce dependency on antibiotics but if not done properly it can have a negative impact on udder health

[pic credit] Teagasc

Further Information 

Read these published research papers from the team: 

Internal teat sealants alone or in combination with antibiotics at dry-off – the effect on udder health in dairy cows in five commercial herds

Evaluation of test-day milk somatic cell count to predict intramammary infection in late lactation grazing dairy cows

Association between quarter-level milk somatic cell count and intramammary bacterial infection in late-lactation Irish grazing dairy cows