Trial indicates farmers could do without antibiotics
Globally, there is concern over development of antimicrobial resistance (AMR). Interest in AMR has increased recently with the emergence of multi-drug resistant “superbugs”. A number of these “superbugs” represent a serious threat to human health.
It is estimated that each year, drug-resistant infections result in 25,000 patient deaths, and cost the EU €1.5 billion in healthcare costs.
There is growing concern regarding the impact of antimicrobial use in agriculture on the emergence of antimicrobial-resistant bacteria. The majority of antimicrobials used in dairy cattle are administered via the intramammary route.
In Ireland, there is widespread use of blanket dry cow therapy (BDCT).
BDCT involves administration of long-acting antimicrobials into all quarters of all cows at drying off. Udder health has improved nationally, and many animals are now uninfected at drying off, since the establishment of the CellCheck mastitis control programme, the improved adoption of practices such as B D C T , re g u l a r m i l k i n g machine maintenance, and improved udder hygiene. In light of such positive trends, it has been suggested that BDCT is no longer required, especially as concerns have been raised that BDCT may lead to an indiscriminate over-use of antimicrobials.
Thus, a key research focus in Teagasc is to investigate mastitis prevention strategies that do not rely on BDCT.
Selective Dry Cow Therapy (SDCT)
Unlike BDCT, where all cows receive antibiotics, selected dry cow therapy (SDCT) involves targeted use of antibiotic treatment, only in those cows shown to have an intra-mammary infection at drying off.
In quarters shown to be uninfected at drying off, a teat seal is administered instead. The addition of teat seal to a SDCT protocol ensures that all quarters have some protection against new infections during the dry period. Herd and individual animal selection is important when considering SDCT. Individual cow milk recording is essential, to allow appropriate selection of cows.
Pilot Teagasc Study
A research herd with a bulk milk SCC consistently under 200,000 cells/mL, and less than 2% clinical case rate in the last three months of lactation, with individual cow milk recording data available, was studied in two concurrent years.
At drying off, cows were deemed eligible for inclusion if their SCC had not exceeded 200,000 cells/mL, and they had not presented with a clinical case of mastitis throughout the previous lactation. Eligible cows were randomly assigned to either Teat