Increasing scrutiny of somatic cell counts at the farm level will force many producers to take a closer look at how they prevent and treat clinical and subclinical mastitis. Here are some dry cow strategies.
By Mark van der List, BVSc MPVM
The landscape for dairy exports is changing and with it comes an evaluation of management strategies to reduce mastitis in the cowherd.
Increasing scrutiny of somatic cell count (SCC) levels at the farm level will force many producers to take a closer look at how they prevent and treat clinical and subclinical mastitis.
The first place a dairy producer might make improvement is in the dry cow program. Dairy cows acquire most new infections during the dry period. Cows are at peak risk for new infections at dry-off and just before calving. The vast majority of these new infections are with gram positive bacteria such as environmental staph, environmental streps and Staph aureus. These intramammary infections are subclinical and may remain so during the subsequent lactation; although a percentage of the infections will eventually result in a case of clinical mastitis.
Dry cow management and treatment is fundamental to successfully reducing mastitis in the cowherd. Dry cow treatment and management can accomplish two things in mastitis control:
1. Cure subclinical gram positive mastitis cases persisting from the previous lactation. Treatment during the dry period generally results in higher cure rates than during lactation.1
2. Prevent new infections.
I recommend the following six dry cow strategies to reduce mastitis and keep SCC levels lower:
1) Mastitis tube selection: The ideal tube will cure existing infection and prevent new infection and therefore the antibiotic needs to persist in the quarter the complete length of the dry period. This may necessitate some milk withhold at the beginning of the new lactation.
2) Dry cow tube administration: It is important to always use proper technique when infusing a tube. This means hygienic preparation of the teat and taking care not to damage the teat end by using minimal insertion tube ends. Make sure to use a teat dip after insertion.
3) Environment: Dry cows need to be housed in a cool, clean, and comfortable environment with dry bedding to minimize exposure of the teat end to bacteria. Avoid overcrowding. Also ensure that the calving areas are clean and dry.
4) Pay close attention to nutritional needs of dry cows. Pay special attention to protein and energy requirements, minerals and vitamins. If mismanaged these can all negatively affect the cow’s immune system, which could result in greater incidences of post parturient diseases including mastitis.
5) Discuss with your veterinarian the benefits of vaccination against coliform bacteria and the possible use of teat sealants to reduce new intramammary infections.
6) Consider culturing fresh cows for mastitis pathogens. This can help identify cows with pathogens such as Staph aureus and Mycoplasma, as well as cows that have acquired a new subclinical infection during the dry period.
You need to continually monitor your dry cow program. I recommend that producers measure individual cow SCC levels toward the end of a lactation and then compare these to SCC levels in first part of the next lactation. When you compare those numbers, an effective dry cow program will maintain or reduce SCC levels below 200,000, the threshold level that indicates an intramammary infection.
Another effective measure of your dry cow program is the number of clinical cases of mastitis occurring in the first 30 days of lactation. An increased number during this period should alert you to re-evaluate your dry cow management. The dry period is critical for mastitis control in dairy herds.
1 Dingwell RT et al. Management of the dry cow in control of peripartum disease and mastitis. Vet Clin Food Anim 2003;19:235–265.
Mark van der List is a Professional Services Veterinarian with Boehringer Ingelheim Vetmedica Inc., and is based in Davis, Calif.