September 2019 Monthly Management

Antimicrobial Resistance (AMR)

Antimicrobial resistance (AMR), is a term used to describe a situation where a medicine that used to work, no longer does. AMR is seen as a global public health threat with the most signs of resistance being found amongst bacteria and antibiotics. Bacteria have existed for a long time and as such they have developed efficient methods of survival. Antibiotics were first discovered in 1928 however bacteria are now developing the ability, when exposed to antibiotics, to become resistant to their effects.

AMR is a natural phenomenon and it cannot be prevented. However, the pace at which it is developing has increased rapidly in recent years because too many antibiotics are being used in both the human and animal health sectors, not just here in Ireland, but at global level also.

How can I play my part?

Not one industry or sector can fix this problem however, we all need to work together if we are to avert this crisis. For those involved with animals, this means doing everything we can to prevent the outbreaks of bacterial infections in our stock. It means using vaccination to prevent outbreaks of viral infections, as viral infections can suppress immunity and increase susceptability to bacterial infections. It means regularly cleaning and disinfecting any equipment that comes in contact with animals. It means isolating sick animals, and when we or our animals are sick, sticking to the 5 R’s:

1. Right Advice - Get the right advice
2. Right Animal - Only give an antibiotic to an animal for which it has been prescribed.
3. Right Antibiotic - The right antibiotic to use is the simplest, most narrow spectrum treatment that will work for the particular infection.
4. Right Dose - Adhere to the right dose
5. Right Duration – Always complete the duration of treatment recorded on the prescription or medicine label. (Article adapted from the Animal Health Ireland CellCheck newsletter)

Selective Dry Cow Therapy

One area specific to dairy farming that is likely to come under pressure from AMR in the near future is the blanket use of dry cow tubes. This traditionally has involved treating all quarters of all cows in the herd with a dry cow tube regardless of the mastitis status of each cow. An alternative practice to blanket dry cow treatments, known as selective dry cow therapy, is one possible method recommended to reduce AMR. In many herds, there may be a certain proportion of cows that do not require antibiotic dry cow tubes at drying off. These are cows that have a consistently low SCC history and have a good health status which are essiental criteria when considering selective dry cow therapy.

When carrying out selective dry cow therapy, accurate animal selction is critical. It is recommended to have milk records of each cow during their lactation with any clinical mastitis cases noted during the year. Milk recording will identify cows suitable for selective dry cow therapy as well as problem cows that will need an antibiotic treatment. In most selective dry cow therapy procedures, cows that are not treated with a dry cow tube should receive a teat sealer at drying off. This will help seal the teat end and prevent bacteria getting in during the dry period. Another area that is essiential for selective dry cow therapy is hygiene at dry-off and clean housing over the winter. Teats need to be disinfected thoroughly in order to avoid introducing a new infection.

Sensitivity analysis to identify the bacteria causing the mastitis issues on-farm will assist in determining the correct dry cow tube to use. This will give best results on cows that are treated.

If we do not act now, the choice may very well be taken out of our hands, whether that is by nature herself, or by those who will be forced to act to protect all our futures.

Lime - The starting Point of Soil Fertility

Soil pH is the foundation for soil fertility and pasture performance. To achieve a target pH of 6.3-6.5, lime needs to be applied; however national figures indicate that we are only spreading approximately 50% of the lime that we need to. Any field that is operating at a low pH is not working to its full potential.

When a soil becomes acidic, the availability of major nutrients (N, P & K) are dramatically reduced. Nitrogen availability can be reduced by 30% and phosphorous can be inhibited by up to 60%. If one bag of 18.6.12 is applied only 12 units of N and 2-3 units of P will be available to the plant for uptake.

Lime is one of the best on farm investments available. It is predicted an extra 1 ton/ha grass production response from lime alone. This is valued at €181/ha/year of extra grass production. At farm level this equates to a return on investment of 1:6. Every €1 spent on lime equates to €6 worth of extra grass produced.

On a cautionary note, excessive use of lime can have a slight negative effect on mineral balances in some soil types. A high pH increases molybdenum uptake, but this can reduce copper availability from the soil (see chart above). This will result in higher risks of copper deficiency occurring in grazing animals. It is recommended to keep pH on high molybdenum soils between pH 6.0-6.2 to avoid this. As a rule, do not to apply more that 3t/ac in a single application. Where the recommendation is more than this quantity, split the application and apply 50% now and the remainder in 2 years' time.

Lime, Slurry and Urea Interactions

CAN and NPK compound fertilisers i.e. 27-2.5- 5,18-6-12, etc.. are all ok to spread any time before or after lime.

The nitrogen content in urea and slurry works differently compared to other fertilisers and requires different management towards lime. A minimum interval of 7 – 10 days after spreading slurry or urea is needed before lime can be applied on the same ground. Avoid spreading slurry or urea to any land following a lime application in the previous 3-6 months. Land that receives lime in the next month will have no issue receiving urea or slurry next spring.

Lime is most effective when it is applied in late autumn/early spring. This will allow the lime to work into the soil and encourage grass growth in spring. Ground limestone should only be applied on silage fields in the autumn. Lime particles present on grass plants may inhibit the ensiling process due to their alkaline properties.

In grazing ground, lime is not harmful to cows but in a worst-case scenario it may cause some slight scouring or palatability issues, however once the lime is washed off the grass there is no risk.

Any fields known to have low pH should be targeted with lime now, if pH is unknown it is recommended to soil test over the winter and put a lime plan in place for your farm. To arrange a soil test of to find out more on soil fertility, please contact your co-op advisor.