Mastitis | Animal movements

Buying replacement cows

Replacement cows may be purchased to increase the size of the herd, to assemble a new herd, or to maintain cow numbers after culling. One of the most common ways of introducing mastitis bacteria into a herd is in and on the udders of cows that are brought in. Bacteria such as Staph. aureus and Strep. agalactiae can spread rapidly through a herd.

New cows entering your herd are a potential source of mastitis, carrying infections than can spread within the herd and potentially increase your bulk milk somatic cell count (SCC). Practical precautions include:

Purchase younger cows where possible.
Check mastitis and SCC records.
Purchase milking cows where possible so that foremilk can be checked for:
- clinical signs,
- somatic cells with a Rapid Mastitis Test,
- bacteria by collection of samples for bacterial culture.
Ensure that all purchased cows are treated with an appropriate antibiotic dry cow and/or teat sealant strategy that aligns with their mastitis history.

When buying replacements or building a herd from multiple sources, consider each cow's disease history carefully to reduce health risks to your herd. More technical advice on this can be found in Technote 19.

Reducing mastitis risk when introducing new animals

Buy heifers before first calving (rather than cows), where possible

It is likely (although not certain) that a heifer that has never been in another dairy area will be free of the major bacterial causes of mastitis.

Don’t buy cows unless bulk milk SCC and mastitis records are available

If the BMSCCs have been less than 200,000 cells/mL for the past six months, the herd of origin is likely to have contagious mastitis under control.

Don’t buy cows unless they have Individual Cow SCC records. Avoid cows with one or more SCC above 150,000 cells/ml and be wary of older cows.

Individual mastitis records, including the results of any on-farm or external milk testing (e.g. cultures), can help to understand what bacteria have been involved in any mastitis episodes.

If cows have received antibiotic dry cow treatment, you should know the product used and the date of treatment.

Check cow’s udders before buying them, and again before milking them

Feel udders for uneven consistency or lumps. Look at teats for teat sores or damage.

If lactating, check foremilk by stripping milk, preferably onto a dark/black surface, and not onto your hand.

Milk containing infection may be spread during this procedure, so gloves should always be used, and rinsed under running water between cows.

If abnormalities are detected, have a milk sample cultured. Knowing if contagious bacteria such as Staph. aureus is present allows infected cows to be managed appropriately e.g. segregated from uninfected cows, treated with antibiotic DCT at dry off. Consult your veterinarian for more advice.

Milk introduced cows last until you are confident that they are free of mastitis

Introduced cows should be regarded as suspect mastitis cases until they have a problem-free lactation in the new herd. Ideally, they should be maintained independent of the home herd.

Consider your farms’ Biosecurity plan and use the biosecurity pre-purchase checklist to help you when buying cows.

Quarantine tips to remember

Milk all newly purchased animals last or with separate equipment as a standard procedure until you are confident they are free from mastitis or other infectious diseases.
Do not put the milk in the vat if there is any suspicion that the milk may contain antibiotic residue.
Consider taking milk samples for bacterial culture.

Avoid introducing mastitis through shared milking

The risk of introducing mastitis by sharing milking facilities with cows from other herds is high. This includes temporarily milking 'carry over' cows for neighbours or sending cows away from your herd to be milked for a temporary period. Where possible, maintaining a closed herd is one of the most effective ways to reduce the risk of introducing mastitis and other infectious diseases. Learn more about farm biosecurity.

In an emergency

In emergency situations, where neighbours need to share milking facilities, operate strict quarantine measures such as:

Separately graze and milk herds.
Ensure that the milking plant and yard is washed between milking different herds.
Ensure that antibiotic cows are kept segregated and milked at the end of each herd.

Mastitis Animal Movement Yard Image 1500X1000

Selling cows

Before selling a cow for slaughter, check treatment records and ensure all meat withholding periods have been met and the animal is free from unacceptable residues. Do not sell animals for slaughter until the full meat withholding period has expired.

Any cow treated with antibiotics should be clearly identified and treatment records kept up to date. While treatment markings may remain visible for the duration of the milk withholding period, they often do not last for the full meat withholding period. For this reason, permanent identification systems and accurate written records are essential.

If selling cows to another farm, provide accurate information on any current treatments and applicable milk or meat withholding periods so the receiving farmer can manage these animals appropriately.