Westpoint Farm Vet’s Tim Potter takes a closer look at the use of selective dry-cow therapy and internal teat sealants, and the correct protocols that should be followed when drying off cows.
The dry period is a critical phase in the productive cycle of a cow, with the combination of environmental and physiological changes she experiences during this time making her susceptible to intramammary infections. The dry period is also a key time for the udder to effectively rest and recover, with existing infections picked up during lactation having a higher cure rate if treated during the dry period compared to treatments administered during lactation. For this reason, using antimicrobials at drying off became standard practice with blanket antibiotic therapy being advocated by guidelines such as the ‘five-point plan’.
Fast forward 60 years and there has been significant progress in terms of both milk quality and udder health. Sub-clinical mastitis rates in UK herds have decreased, with the proportion of UK herds with fewer than 10% chronic high SCC cows increasing from 24% of herds in 2010 to 62% of herds in 2019. And there are fewer cows suffering from udder infections at the time of dry off. This improvement in the control of contagious mastitis means the emphasis at the start of the dry period has moved from one of cure to prevention.
As well as improvements to mastitis control, there has been increasing focus on overall reduction in the use of antibiotics. While the dairy sector uses relatively few antibiotics compared to other livestock sectors, the majority of antibiotic use in dairy herds is related to udder health, and a significant proportion is dry-cow therapy.
Moving away from blanket use of antibiotic dry-cow therapy and towards selective dry-cow therapy (SDCT) has contributed to a significant reduction in antimicrobial usage on many dairy farms, with the RUMA reporting success in the reduction of the usage of antibiotic dry-cow therapy against its 2020 targets. The use of internal teat sealants has played a key role in the move towards SDCT, but many herds are yet to make use of this tool. At the start of the dry period, a keratin plug (made from a wax-like substance) seals the teat canal and prevents bacteria from entering the udder. But studies have shown that nearly 25% of teat ends remain open up to six weeks after dry-off, leaving cows more susceptible to infection.
Teat sealant: use is essential to prevent new infections
Teat damage, such as hyperkeratosis or cracked teats, as well as high milk yields can further increase the variability in the keratin plug formation. Internal teat sealants effectively simulate the cow’s natural keratin plug and act as a barrier throughout the dry period. Studies reveal that cows treated with teat sealants at drying off are at a lower risk of developing new intramammary infections at calving compared to those not given any form of dry-cow therapy. Cows not given an internal teat sealant at drying off also had a 2.8 times greater risk of developing new intramammary infection at calving compared to those given a teat sealant.
The Dairy Antimicrobial Focus report, published by Kingshay in February 2022, found that 37% of herds monitored were not using any teat sealants at all, and that overall teat-sealant usage was still below the RUMA targets set by the industry for 2020. These figures highlight the opportunity for producers to make better use of these products as part of SDCT protocols. Appropriate training around use of teat sealants is essential, as improper use and poor hygiene can result in bacteria being trapped inside the udder, which has the opposite effect on cow health and productivity. However, when used properly, teat sealants coupled with good husbandry can support udder health, and the reduction of overall antibiotic use.