Drying-off early - decisions and deadlines
As we approach the time of the year when you should be thinking about who, when and how to dry-off, it is helpful to go back to basics to aid your decision making.
Who: Cow condition and health throughout the season may help you make this decision. Chronic mastitis sufferers should be culled. Those cows that have lost condition or never regained condition since calving are candidates for drying-off. Similarly, young cows, low producers and high somatic cell count cows should be dried-off early.
Reducing the number of milkers frees up feed for the better producers, allowing them to be milked for longer, as well as allowing the dried-off cows and the milkers greater opportunity to put on condition.
When: Drying-off depends not only on cow condition and your current feed situation, including what you have on hand for winter, but also your calving date and what treatment regime, if any, you are planning on using. Different dry cow antibiotics have different periods of efficacy and therefore withholding times, and it is important to factor this into your planning.
How: The drying-off process can take 4 to 10 days. This will be determined by the level of milk production when you decide to dry-off. Higher producers will take longer. Reduce dry matter intake to maintenance levels 3 to 4 days before your planned dry-off date and change to a low protein diet by reducing pasture intake and feeding low protein feeds such as maize silage, silage or hay.
When drying-off, do not restrict water intake or make any sudden change to their diet. Starving cows at drying-off can be associated with more mastitis in the following lactation.
Immediately after their last milking, treat with the appropriate dry cow antibiotic with or without a teat sealant. Vividly mark and separate these animals from the milking herd. A week or so after drying-off, run the cows through the shed and check for mastitis. Teat spray at this time to further minimise the risk of mastitis during the dry period.
Good science behind combination drying-off treatment
The objectives of a good dry-cow treatment programme are to
- Cure existing infections
- Prevent new infections during the dry period
Dry cow antibiotics achieve the first objective and prevent new infections during the early dry period, for however long their period of activity. While there is a good cure rate on post drying-off infections in dry cows, with up to 80% being cured during the dry period, the activity of dry-cow antibiotic declines over time, meaning its protective effect against a new infection is negligible past 50 days, even with the most powerful treatments.
In herds with high bulk milk somatic cell counts (SCC) it is often necessary that higher SCC cows be dried-off earlier as milk volumes decline in late lactation and grade avoidance becomes the name of the game. However, having a dry period of greater than 50 days sets those same cows up to be susceptible to infection the following season, due to the fading effect of dry-cow antibiotic, and within cow susceptibility to infection.
Why individual cows are more susceptible to infection has numerous answers including her previous mastitis history, the length of the dry period, milk yield at drying-off, nutritional/trace element status and how quickly she forms the keratin plug in the teat canal after drying-off.
Teat sealants effectively mimic the keratin plug, and infusion at drying-off will see the product sit in the teat sinus, preventing bacteria entering well after the effects of dry-cow antibiotics have waned. Sealants reduce infection over lengthy dry periods.
Combination treatments of high cell count cows at drying-off with antibiotics and a teat sealant have been shown to reduce the incidence of new infections at calving by half. In cows with a dry period longer than 10 weeks, only a third as many cows were infected under combination treatment, compared with those treated only with antibiotic.
A trial carried out by Richard Laven at Massey University has shown combination treatments can carry positive benefits for mastitis management into the new season. Cows treated with dry-cow antibiotic plus teat sealant had half (8%) the infection rate of those treated with antibiotic only (15%).
A cow that has had clinical mastitis during the season and a cell count over 150,000 should definitely have antibiotic. If she is going to be dry for more than 10 weeks, then a teat sealant should be considered to ensure a barrier to further infection before calving.
A cow with a low SCC through the year and no mastitis may be an ideal candidate for teat sealant treatment only.
Dry cow antibiotics are a prescription animal remedy and cannot be prescribed without a prior veterinary consultation. If you haven't already received Totally Vets Drying Off Consultation for 2008/09 questionnaire, pick one up from either branch. Completing this as thoroughly as you can goes a long way to fulfilling the requirements of a consultation. Without information our promise of best advice is difficult to deliver on when we set aside dedicated time to go through it with you.
