Jeremy Heim likes having mastitis information at his fingertips. Heim has been culturing suspected quarters for mastitis pathogens for about two years. And he’s doing it right on the dairy.
In as little as 24 hours, Heim has the culture results in hand and can make an informed treatment decision at Heim’s Hillcrest Dairy, a 340-cow operation in Kewaunee, Wis. Otherwise, he would have to wait two or three days for results to come back from his veterinarian before he could take appropriate treatment action.
Heim says on-farm culturing has reduced his treatment cost. The culture results tell him if the organism is Gram positive or Gram negative. That way, he doesn’t waste money treating Gram-negative bacteria — the ones that don’t respond to antibiotic therapy. Heim also has advanced to the point where he can use the system to differentiate between Strep and Staph species in order to further fine-tune treatment protocols.
It doesn’t take a lot of fancy equipment or expertise to culture milk samples on-farm. In fact, it’s best to keep things simple when you first start culturing milk samples.
“Start out with the basics and learn how to walk before you run,” advises Russ Bey, veterinarian at the University of Minnesota. Bey and colleagues at the University of Minnesota Laboratory for Udder Health developed the “Minnesota Easy Culture System,” a simple, easy-to-use culturing system for use on-farm.
Here’s the basic equipment you need to get started culturing milk samples on-farm:
1. A clean work area. You don’t need a separate room to culture milk samples. Simply use a countertop in an existing office or designate another clean, dust-free work space for your equipment.
2. Milk-collection tubes. You can usually obtain these from your milk hauler or milk-processing plant at no charge to you or for a nominal fee. Use them to collect a milk sample from a suspected quarter.
3. Culture plates. To keep things simple, start with bi-plates. As the name implies, bi-plates are split in half. Each half contains a different type of media or agar — a substance on which the bacteria can grow. Culture plates come with the media already on them. All you do is add some milk and wait about 24 hours for the bacteria to grow. The table below summarizes two common types of media found on bi-plates.
Bi-plates are good for beginners because they give you a simple “yes” or “no” answer. Is the bacterial growth on the red side or the pink? If you observe growth on the red side, the organism is most likely Gram-positive. Growth on the pink-colored media indicates a Gram-negative organism.
You can purchase culture plates from the University of Minnesota Laboratory for Udder Health, (800) 605-8787. Cost is $2.80 per bi-plate, plus shipping. The media on the plates has a shelf life of roughly five to six weeks, so don’t purchase huge quantities at one time.
Other laboratories or suppliers may prepare and sell milk-culture plates for use on-farm. Before you buy, make sure the lab runs a quality-control test on the plates it sells. This test assures you that the media will react properly and grow the right organism.
4. Sterile cotton-tipped swabs. You will need these to apply milk from the sample onto the culture plate. Look for them in a farm-supply store or catalog. Some milk-quality labs also sell them. Cost runs about a penny or less per swab.
5. Incubator. After you’ve put the milk sample on the culture plate, incubate the plate for 18 to 24 hours at 37 degrees C. All you need is a simple egg incubator with a fan. The fan circulates air inside the incubator. You can find one of these in a farm-supply store or catalog such as Nasco Farm & Ranch Catalog, (800) 558-9595. Cost ranges from $60 to $100.
6. Laboratory handbook. Until you become familiar with identifying the organisms on the plate, you will need a reference guide to help you interpret the results. The Minnesota Easy Culture System Handbook, available from the University of Minnesota Laboratory for Udder Health, (800) 605-8787, is a good choice. The handbook is specifically designed for use on-farm. It includes a description of common contagious and environmental mastitis pathogens, as well as a flow chart and color pictures of culture plates to help you identify what organism is present.
7. Refrigerator. If you won’t be able to plate the milk sample immediately, you will need to either refrigerate or freeze it within 15 minutes of obtaining the sample. Most dairies already have a refrigerator handy.
It’s easy to get overwhelmed when you start culturing milk samples on-farm. However, if you start with the basics listed here and work your way up from there, you’re more likely to have a positive experience and one that will benefit your milk-quality program in the long run.
For more information: Call your veterinarian, or the University of Minnesota Laboratory for Udder Health at (800) 605-8787.
Designate the task
One of the most important things you can do when setting up an on-farm mastitis-culturing lab is to identify one person to perform this task. Just make sure the person responsible for the task has an interest in doing it. Correct interpretation of the culture results is important to the success of an on-farm mastitis-culturing program.
Include your veterinarian
If your dairy averages four to six mastitis cases per week, then it’s probably economical to do on-farm culturing for mastitis pathogens, says Russ Bey, veterinarian at the University of Minnesota. However, discuss the entire process with your veterinarian first. In addition, involve your veterinarian in all treatment decisions and treatment protocols.