Antibiotic Dry Cow Treatment (DCT) is used to:
- Treat existing infections that have not been cured during lactation
- Reduce the number of new infections that may occur during the dry period.
Internal Teat Sealants (ITS) are used to:
- Protect uninfected quarters during the dry period and at calving
- Extend protection provided by DCT.
More information about antibiotic DCT
- Antibiotic DCT is a formulation of antibiotic that is administered into the udder immediately after the last milking of a lactation. It is designed to remain in the udder in concentrations high enough to kill mastitis bacteria, which can be between 20 to 70 days, depending on the product used. The prolonged period and the formulation help the antibiotic to penetrate into the tissues and increase the chance of curing infections embedded deep in the udder.
- Antibiotic DCT can also protect udders from new infections in the dry period. This occurs directly through antibiotic being infused soon after drying off, and indirectly by promoting more rapid physical sealing of the teat canal after drying off.
- Antibiotic DCT does not protect against some environmental bacteria which may be introduced into the udder if administration is not done very cleanly. These environmental bacteria may cause severe clinical mastitis.
More information about ITS
- ITS contains the non-antibiotic product, bismuth sub-nitrate, an inert material that stays inside the teat throughout the dry period. It provides a physical barrier inside the teat and teat canal that stops bacteria moving up into the udder and causing an infection.
- ITS can extend protection by an antibiotic DCT, when administered immediately after the antibiotic tube, at drying off. This may be appropriate for cows with extended dry periods (beyond 8-10 weeks), for higher SCC cows, or for herds with a particularly high risk of mastitis at and around calving
- As ITS contain no antibiotic, they will not kill bacteria already inside the gland. Therefore cows suspected to be infected (e.g. high SCC) should not be treated with ITS only. Also, ITS cannot kill bacteria that may be pushed inside the teat canal if the administration is not done very cleanly. These environmental bacteria can cause severe mastitis.
14.1 - Calculate drying-off dates to ensure that all cows get at least six weeks (preferably eight weeks) dry period
After each lactation, dairy cows require a dry period that is sufficiently long to allow the udder tissue to repair and rejuvenate. Many of the cells that produce milk are removed and replaced again before the next calving. A minimum of six weeks (preferably eight weeks) is recommended between drying-off and calving.
Use expected calving dates, production levels, body condition scores and feed availability to calculate drying-off dates so that all cows get at least a six week dry period. If operating a split calving pattern, take extra care to ensure that individual cows have a dry period of at least 6-8 weeks (42-56 days).
In many herds, it is practical to stagger drying off over a number of weeks or days.
14.2 - Dry off high SCC cows early to help lower bulk milk SCC
Cows with high SCC can jeopardise milk quality, especially towards the end of the season when milk volumes are low. Dry them off early and cull, or use antibiotic DCT on these cows if they are being kept for the next lactation.
Antibiotic Dry Cow Treatment (DCT)
Antibiotic DCT are used in cows at drying-off to treat pre-existing infections, and help protect them from environmental mastitis infections during the dry period and prior to calving. They are a long-acting formulation of antibiotics and should only be infused into the teats after the last milking of lactation. Care must be taken to ensure that the dry period of individual cows is longer than the withholding period of the selected DCT product.
Internal Teat Sealants (ITS)
Teat sealants are used in cows at the time of drying-off to help protect them from environmental mastitis infections during the dry period and prior to calving. They are infused into the teats after the last milking and stay in the lower part of the teats throughout the dry period, physically preventing bacteria from entering the teat canal. Teat sealants are not antibiotics. These do not cure infected cows.
Whole herd approach
See Guideline 14.4 to plan your treatment approach for the whole herd.
14.3 - Collect data to assess herd level of mastitis
You will require:
Bulk milk SCC for the last six months
Records of clinical cases
Individual Cow SCC - at least three herd test results are needed, spread through the current lactation, to make individual cow decisions about antibiotic DCT or ITS. It is unreliable to use single herd test results to select cows for ITS.
Generate a Mastitis Focus report for your herd
Check the box on Previous dry-off strategies to review performance during last dry period.
14.4 - Plan to use appropriate treatment or prevention for all cows in the herd
SmartSAMM recommends that all cows are protected by some treatment during the dry period. This is likely to include antibiotic DCT in high SCC cows, and antibiotic DCT or ITS in low SCC cows.
Possible approaches include:
1. Whole Herd DCT
Treat all quarters of all cows with antibiotic DCT if:
- You have insufficient records to make individual cow decisions
- The risk of dry period mastitis is considered to be HIGH in your herd.
2. Part Herd DCT
Treat all quarters of all cows considered to be at risk of infection with antibiotic DCT. Cows that are considered to be “at risk” include:
- Cows treated for clinical mastitis in the last dry period or in current lactation
- Cows with one or more SCC above 150,000 cells/mL in the current lactation
- Heifers with one or more SCC above 120,000 cells/mL in the current lactation
- Cows with no herd test records or animal health treatment records.
All other cows may be treated with a non-antibiotic internal teat sealant (ITS), if the following is true:
- You have sufficient records to make individual cow decisions
- The risk of dry period mastitis is considered to be LOW in your herd.
Consult your veterinarian
- To identify your herd’s risk of mastitis in the dry period, and next lactation
- To decide the most appropriate treatment approach for your herd.
Reduce risk of antibiotic residues
- Do not treat blind quarters with antibiotic DCT
- Do not treat cows which are to be culled after drying-off.
See Guideline 14.3 for a definition of sufficient records to make decisions about individual cows.
See Technote 14 for more information on selecting your dry cow treatment strategy.
14.5 - Consult with your veterinarian to select the most appropriate antibiotic DCT for your herd
Your veterinarian will help you assess factors such as:
Previous culture results and antibiotic responses on your property
- Published cure rates of products for existing infections
- Claimed period of protection of products for new infections
- Minimum dry periods of products and anticipated dry period lengths of cows
- Suitability of a combination of approaches for your situation.
Hygienic preparation of the teat before infusing intramammary treatments is critical, especially for ITS.
- See Healthy Udder - Treat 3 for a practical guide.
- Discuss the training needs of your team with your veterinarian.
14.6 - Purchase and store the antibiotic DCT and ITS you will need at drying off
Order and purchase the required number of tubes for all quarters of all cows to be treated, well ahead of your planned dry off dates. Make sure you have some available for cows that are dried off early.
Store in a cool, clean environment, preferably in a refrigerator.
Under cold conditions, warming of intramammary products before use is sometimes helpful to reduce viscosity. This is best done by storing the products in a warm dry place for the night before use, or by using a ‘water-bath’ technique. This involves keeping the tubes inside a dry container (e.g. original bulk container or bucket), which is in turn floated in a larger container of hot water for a period of time to warm the product through.
Avoid accidental treatment of milking cows with DCT
Do not store antibiotic Dry Cow Treatment near tubes of Lactating Cow antibiotic.
Purchase fresh supplies of teat wipes
Containers of wipes, once opened, dry out quickly over a few days and are then ineffective.
Keep products clean before use
Under no circumstances should tubes of ITS (internal teat sealant) or antibiotic DCT be made wet or dirty before use, as this greatly increases the risk of environmental bacteria being introduced into the udder, and causing a severe mastitis.