ADCT has been established for over 50 years and in 1963 blanket antibiotic dry cow therapy, mainly to control contagious mastitis pathogens, was one of the main pillars of the ‘Five-point mastitis control plan’.
With anti-microbial resistance predicted to rise to 10 million human deaths per year by 2050 if nothing is done¹, governments, human health agencies, consumer groups and food retailers are putting greater pressure on food producers to rationalise the use of antibiotics.
Selective dry cow therapy (SDCT) is the decision about whether a cow receives an antibiotic dry cow tube in addition to an internal teat sealant such as Boviseal.
What is the purpose of dry cow therapy?
The dry period allows the cow and her udder to recover and regenerate.
The aim of dry cow therapy is to optimise the chances of a cow calving with a low somatic cell count (uninfected) and being at low risk of developing clinical mastitis in the next lactation. The dry period represents the best opportunity to cure existing infection, however it is still essential to prevent new infections.
Treatment of existing intramammary infections – use of an antibiotic.
Prevention of new intramammary infections – use of an internal teat sealant (eg Boviseal).
It is essential that all other aspects of dry cow management are optimal.
What is selective dry cow therapy (SDCT)?
All cows benefit from the prevention of new infections by using Boviseal teat sealant but not all cows need antibiotics during the dry period. If a cow does require an antibiotic dry cow therapy, then it is about selecting the most appropriate product for the cow’s requirements - this may be broad or narrow spectrum.
Implementing a SDCT programme that consists of all cows being treated with Boviseal can reduce antibiotic usage in two ways:
Reduced clinical mastitis treatment:
By imitating the cow’s natural keratin plug, Boviseal prevents mastitis-causing bacteria from entering the teat during the entire dry period, consistently reducing clinical mastitis by around 35% in the subsequent lactation 2,3.
Reduced antibiotic use in dry cow therapy:
SDCT reduces the use of dry cow antibiotics but requires an effective teat seal throughout the dry period. Boviseal is proven to work with or without a dry cow antibiotic. This has been demonstrated in many clinical trials with Boviseal2,3,4,5.
What information is required to implement SDCT on farm?
When implementing SDCT on farm, it is essential to gather enough information to decide whether the herd is suitable and which cows within the herd could be dried off with Boviseal only.
At a minimum the following information is required:
Bulk milk somatic cell count (SCC).
Individual cow SCCs (four times minimum).
Clinical mastitis records.
Ideally clinical mastitis samples and samples of high SCC cows should be submitted throughout the year to determine the prevalence of gram-positive (eg Staph aureus, Strep uberis) and gram-negative bacteria (eg E. coli) on farm.
Which herds or cows are suitable for SDCT?
Not all herds or individual cows will be suitable for SDCT. With SDCT all cows are treated with an internal teat sealant, such as Boviseal, with or without a targeted antibiotic therapy. SDCT does not mean you have to stop using antibiotics altogether.
Herds suitable for SDCT have6:
Bulk milk SCC < 200,000 cells/ml.
Recent infection rate <5%.
Clinical mastitis <2% of cows over the last three months.
Excellent hygiene at dry off.
Cows from suitable herds have:
Individual cow SCC’s <100,000 cells/ml.
No cases of clinical mastitis.
A negative California mastitis test (CMT).
Thresholds may vary up or down, in discussion with the veterinary practitioner, depending on the farm’s individual situation, but hygiene at dry off should never be compromised.
For cows that require treatment, which antibiotic dry cow therapy is suitable for an individual farm?
The choice of antibiotic dry cow therapy may depend on the prevalence of bacteria.
Broad spectrum products are effective against both gram-positive and gram-negative bacteria, whereas narrow spectrum antibiotics kill gram-positive bacteria only.
As a rule of thumb, high somatic cell count cows, or cows suffering from chronic or recurrent mastitis cases are more likely to suffer from a gram-positive infection.
These cows would benefit from a targeted treatment with a narrow spectrum product as these have been shown to have better activity against gram-positive pathogens such as Staph aureus and Strep uberis than broad spectrum antibiotics7.
When faced with the prospect of selective dry cow therapy farmers should talk to their vet who will consider their individual farm situation when deciding which cows should receive Boviseal alone and which antibiotic should be used alongside Boviseal for the remainder of the herd. The more information that is available the more accurate the decision in ensuring the right cow receives the right treatment.
Compulsory implementation of SDCT will happen by 2022 so it essential for farmers to start gathering information now and plan for the change.
1 Jim O’ Neill (2016). Review on anti-microbial resistance.
2 Rabiee AR & Lean IJ (2013). The effect of teat sealant products (Teatseal and OrbeSeal®)* on intramammary infection, clinical mastitis, and somatic cell counts in lactating dairy cows: A meta-analysis. J Dairy Sci 96:1-17.
3 Godden S. et al. (2003). Effectiveness of an internal teat seal in the prevention of new intramammary infections during the dry and early-lactation periods in cows when used with a dry cow intramammary antibiotic J. Dairy Sci. 86 (12):3899-911.
4 Mütze K. et al. (2012). The effect of dry cow therapy with and without an internal teat sealant on udder health during the first 100 d. of lactation: a field study with matched pairs. J. Dairy Res. 79 (4):477-84.
5 Berry EA et al. (2002). The effect of selective dry cow treatment on new intramammary infections. J Dairy Sci 85(1):112-21.
6 Animal Health Ireland
7 Marco, J.C.; Escobal, I. and Aduriz, J.J. (1995) Efficacy of different dry cow preparations in the control of mastitis The 3rd International Mastitis Seminar Proceedings, Vol 2, 122-123.