Department of Primary Industries:
Dry Cow Therapy
Over the next few months many dairy farmers will be thinking about drying off their herd. Decisions on dry cow therapy are never easy and may have a huge effect on the profitability of the farm for the future lactation.
By Department of Primary Industries - 23rd April 2003 - Back to News
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Over the next few months many dairy farmers will be thinking about drying off their herd. Decisions on dry cow therapy are never easy and may have a huge effect on the profitability of the farm for the future lactation. Drying cows off with antibiotics should be seen as only one part of a good mastitis control program. Their major use is to cure infections. A good mastitis program should prevent infections occurring as well as curing existing ones.
Having said this, dry cow therapy can be used to prevent infections occurring in the dry period. Primarily, new infections are caused by environmental bacteria at this time of the year. Treating the whole herd with a dry cow antibiotic may be recommended if your herd has a history of Streptococcus uberis or E. coli infections.
Protection from environmental bacteria aside, the major use of dry cow antibiotics is to cure existing infections within the udder. Dry cow preparations are more successful at clearing infections than tubes given during lactation as the antibiotics are administered at a high concentration and are left in contact with the bacteria for a long period of time. Although persistent antibiotics achieve better cure rates that cannot be used during lactation as they cause unacceptable residues in the milk.
Nowadays farmers have many options when considering drying off their cows. A history of the incidence of mastitis, Bulk Milk Cell Count (BMCC) and Individual Cow Cell Count (ICCC) and culture results if available, should all be used to make a logical decision.
The following facts should be kept in mind if deciding not to use dry cow therapy: the chance of new infections is greatest in the early dry period; of the infections already present at the start of the dry period, 90% will persist into the next lactation; a quarter with a persistent subclinical infection will give about 30% less milk in the next lactation.
Your local veterinarian should be consulted if deciding to use dry cow preparations. They are well positioned to give advice on which program to follow and the best type of antibiotic to use on particular properties. The choice of which cows to treat will depend on the methods used to detect mastitis within the herd.
1. Blanket therapy refers to treating all quarters in all cows in the herd. This program is often recommended to reduce levels of infection when the mastitis status of individual cows is unknown. Although the costs are significant, all subclinical infections are treated and all cows get protection through the dry period.
2. Selective dry cow therapy refers to treating all quarters of those cows, which have been infected during the previous lactation. To reduce mastitis within the herd, this method relies on accurately identifying infected cows. Records can be examined to identify cows, which have had a case of clinical mastitis during the past lactation. Subclinical infections are assessed by ICCC or by one of the rapid mastitis detectors or tests. It should be noted that examining the results from a single test is unlikely to give accurate information on the subclinical mastitis status of an individual cow or a herd. There are also limitations on the accuracy of the results from some of the rapid mastitis detectors so care is needed in interpreting these results.
Having several ICCC results during a cow’s lactation gives the best indication of her mastitis status. Some farmers have trouble interpreting the herd improvement data. In these cases it is best to seek professional guidance. It is a false economy to pay for the collection of the data and not use it effectively. Advisers may also vary the individual cell count target thresholds for treatment depending on the farmer’s mastitis control aims.
The correct decisions on dry cow treatment should be made by farmers and their advisers as a part of an overall mastitis strategy. Only then can the benefits of dry cow therapy be fully appreciated.
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