Antibiotic use on dairy farms

Antimicrobial use in livestock continues to be a prominent topic in the mainstream media.

As gatekeepers of antibiotic usage, vets  play a key role to reduction through raising awareness and non-antimicrobial disease prevention.

Below we've listed alternative treatments for six common diseases to help reduce antibiotic use. Each shows an example situation along with three possible treatment options.

Example Scenario:

Farmer A has a 100-cow dairy herd, milking twice daily in a herringbone parlour.

The farmer has noticed many cows are lame following housing. His foot-trimmer has found that six of the 20 cows trimmed that day had acute digital dermatitis lesions.

Keen to control the disease, Farmer A discusses options to control the apparent outbreak of digital dermatitis with his vet.

Example treatment options

Option 1 – Inappropriate use
All cows are walked through a monthly antibiotic footbath. This is off license, requiring a minimum 7 day milk and 28 day meat withdrawal, and equates to 28mg/PCU of antibiotic that will usually end up in the slurry store.

Option 2 – Improved approach
All cows are screened in the parlour using a mirror and any with active digital dermatitis are separated and spot treated with antibiotic spray for three days.

This targeted treatment approach uses a negligible quantity of antibiotic and is within the licensing rules, no milk withhold is necessary.

Option 3 – Best practice
In addition to option 2, a preventive non-antibiotic foot bathing regime is introduced, leaking water troughs are repaired and hygiene is improved.

This approach uses a negligible quantity of antibiotic in the short term, and also reduces the number of new cases. Long term antibiotic use will decline and animal health will improve.

Example Scenario:
Farmer B has a 500-cow dairy herd. The farmer has had trouble with clinical mastitis in the herd.

Keen to control the disease, farmer B discusses options to control mastitis with their vet. Data analysis reveals an incidence rate of 90 cases/100 cows each year, with about 15% of cases being repeat cases.

Example treatment options

Option 1 – Inappropriate use
Change intra-mammary tube and treat every case with an intramammary tube and injectable systemic antibiotic, hoping it reduces recurrence.

This approach uses approx. 30mg/PCU of antibiotic however, there is no evidence that injectable antibiotics will have any meaningful impact on cure rates or repeat cases.

Option 2 – Improved approach
Mastitis detection is improved by fore-stripping, cases are treated earlier with intramammary tubes only, and the client reminded that cure rates for the existing recurrent cases in lactation are likely to be poor but cure during the dry period is much better

This treatment approach uses approximately 1.5 mg/PCU.

Option 3 – Best practice
In addition to Option 2 and in consultation with your vet, reduce the level of mastitis by implementing the AHDB Dairy Mastitis Control Plan.

This approach uses 1.5mg/PCU antibiotic in the short term as per Option 2, but also reduces the number of new cases. Long term antibiotic use will decline and animal health will improve

Example Scenario:
Farmer C owns a 150-cow dairy farm rearing its own replacements.

Calves are group-housed in converted stables and often develop pneumonia (or BRD – bovine respiratory disease) in the spring. This year when the usual outbreak occurs, two in a group of 30 calves die and another four are coughing and appear sick.

Example treatment options

Option 1 – Inappropriate use
Treat all calves with florfenicol antibiotic injection. Treatment of all 30 calves uses ~1.4mg/PCU of antibiotic .

Option 2 – Improved approach
Improve detection to treat cases earlier and only treat those calves affected with florfenicol antibiotic and an anti-inflammatory.

This treatment approach uses approx. 0.2 mg/PCU of antibiotic.

Option 3 – Best practice
In addition to Option 2 and in consultation with your vet, plan to prevent BRD by taking specific preventive measures appropriate for the farm situation such as reducing infection pressure (e.g. better ventilation), and improving immunity (e.g. colostrum management). Also consider pneumonia vaccines and BVD eradication.

This approach uses 0.2mg/PCU antibiotic in the short term as per Option 2 but also reduces the number of new cases. Long term antibiotic use will decline and animal health will improve.

Example Scenario:
Farm D is a 400 cow dairy which block calves. The farmer notices nearly 10% of cows calving go on to develop signs of metritis (high temperature, vaginal discharge) the following week.

These cows often go on to develop endometritis (whites) and are difficult to get back in calf. They consult their vet about their options to tackle this, as their conception rates are reducing and the calving interval getting longer.

Example treatment options

Option 1 – Inappropriate use
Treat all affected cows with ceftiofur, a zero-milk withdrawal 3^rd generation cephalosporin

This approach uses approx. 1mg/PCU of antibiotic however, 3^rd generation cephalosporins are classified as ‘Highest Priority Critically Important Antibiotics’ (HP-CIAs) and use should be avoided.

Option 2 – Improved approach
Treat all cases with amoxicillin or cephalexin, neither of which are HP-CIAs.

This treatment approach uses approx. 3.5 mg/PCU, typically with a 3-day withdrawal. While this uses more antibiotic by weight, it avoids using an HP-CIA.

Option 3 – Best practice
In addition to Option 2, the vet advises preventive strategies (e.g. changes to transition cow feeding and management) to reduce risk of ketosis and milk fever in fresh-calved cows.

This approach uses 3.5mg/PCU antibiotic in the short term as per Option 2, but also reduces the number of new cases. Long term antibiotic use will decline and animal health will improve.

Example Scenario:
Farm E is a 200-cow dairy farm producing 9,000 litres of milk per cow each year.

The herd manager has noticed a lot of lame cows with sole ulcers. There are 10 cows that are severely lame, all of which have sole ulcers when examined.

Example treatment options

Option 1 – Inappropriate use
Trim the cows feet and treat them with three days of Tylosin, an injectable macrolide.

This approach uses 2.1mg/PCU per treatment with a 3-day withdrawal. There is no evidence that antibiotics will improve the cure rates of non-complicated sole ulcers.

Option 2 – Improved approach
Treat the cows with a foot trim, block and non-steroidal anti-inflammatory drug (NSAID).

This treatment approach uses no antibiotic. Blocks and NSAIDs have been shown to improve outcomes in cows with claw horn disease.

Option 3 – Best practice
In addition to Option 2, fortnightly mobility scoring is used to identify and then treat early cases of lameness.

This approach uses no antibiotic in the short term and also results in treating cases sooner, increasing their chances of recovery and reducing the number of lame cows overall.

Example Scenario:
Farm F is a 400-cow spring calving Jersey-cross herd producing 5,000 litres of milk/cow each year.

It is approaching drying-off time and the farmers want to review the protocols.

Clinical mastitis case rate is 90 cases/100 cows each year, bulk milk somatic cell count is 210,000 cells/ml and the last milk recording shows that 25% of the herd had somatic cell counts of over 200,000 cells/ml at any one of the previous three recordings.

Example treatment options

Option 1 – Inappropriate use
Give all cows antibiotic dry cow therapy, an internal teat sealant, and inject high cell count cows with a macrolide.

This approach uses approx16mg/PCU of antibiotic for all these treatments together. There is no evidence that injectable antibiotics will have any meaningful impact on cure rates; in most herds, >90% of mastitis infections will be cured with antibiotic dry cow tubes alone.

Option 2 – Improved approach
Give all cows an internal teat sealant at drying off. Treat only those with a high cell count (>200,000 cells/ml) with antibiotic dry cow tubes at drying off.

This treatment approach uses approx1.4 mg/PCU antibiotic and may also result in less clinical mastitis in early lactation. Strict hygiene is essential.

Option 3 – Best practice
In addition to Option 2, the AHDB Dairy Mastitis Control Plan is introduced in consultation with the vet.

This approach uses approx1.4mg/PCU antibiotic in the short term as Option 2, but also reduces the number of new cases. Long term antibiotic use will decline and animal health will improve.