29 April 2022

Dairying and Antimicrobial Resistance (AMR)

AMR is a new challenge to the farming community and a risk to public health. Don Crowley, Teagasc Dairy advisor discusses antimicrobial resistance, how it develops and the importance of milk recording in the absence of preventative antimicrobials, on the dairy farm

Change is part of farming, a constant evolution and adaptation to new challenges and research that shape the way farmers run their business. AMR has a significant impact on the way farmers deal with disease challenges on their farm.

Antimicrobial resistance (AMR) occurs when bacteria, fungi, viruses etc. that cause infections adapt and prevent antimicrobial products from working against it. At farm level, antimicrobials used to treat infections may no longer be effective and so common infections are more difficult to treat.

So how does resistance develop?

Antibiotics when administered to an animal kill, most of the harmful bacteria, but some will survive and these are the resistant bacteria. Resistant bacteria multiply and pass on their resistant genes, enabling the bacteria population develop resistance to the antibiotic. Because bacteria under the right conditions can multiply so rapidly, the resistance to an antibiotic can become established very quickly.

Under new legislation, the use of antimicrobials to prevent infection is outlawed. An example of this practice is blanket dry cow therapy. This was where, as a preventative measure, every quarter of every cow would receive a dry cow antibiotic preparation, whether there is an infection present in the udder or not.

Since January 2022, this practice is not allowed and only infected cows can receive antibiotics. The rest of the herd must only receive a sealer following veterinary advice.

Milk Recording

Milk Recording is the only way to accurately identify cows that have had an infection during the previous lactation. Based on the milk recording results at the end of the year, a plan for drying off cows must be developed to help prevent and treat new infections. Milk recording and recording of clinical cases of mastitis with accurate culture and sensitivity analysis during the lactation is crucial to make accurate decisions at dry cow time.

AMR is a major public health concern and poses a serious threat to disease control throughout the world. New antibiotic molecules have not been discovered for a number of years. Antibiotics are crucial to protect animal health and welfare and enables the production of safe sustainable food. Antimicrobial resistance is a natural process that will occur when antibiotics are used, as every time antibiotics are used bacteria have the chance to develop resistance.

The trick is to slow this process down and use other means to prevent the need for using antibiotics. Good husbandry, nutrition, genetics and preventative health care (e.g. vaccines) are major ways to help slow and prevent the development of AMR.

The 6 R’s

Antibiotics should only be used as a last line of defence and the 6 R’s should be followed when using antibiotics:

Right Veterinary Diagnosis
Right Animal
Right Antibiotic
Right Dose
Right Duration
Right Storage and Duration

The problem of AMR has arisen due to the inappropriate use of antibiotics in animals and humans that is leading to a rapid development and spread of AMR. With proper use and high levels of animal husbandry, AMR can be greatly curtailed. Antibiotics should never be used to compensate for poor management.

Dairy farmers must prepare for a major change in how to dry off cows in the autumn of 2022. One step in the short-term is to sign up for milk recording to ensure that you achieve at least 4 to 6 recordings before drying off to give you a better picture of infection levels in the herd throughout the year. The help and expertise is available through your Agricultural Adviser, Co-op Milk Quality Advisor and your Veterinary Surgeon to help guide you in the development of an appropriate plan for your farm.