Raising the Bar on Mastitis

On Mastitis Detection and Management

The impact of mastitis can be staggering. With each case of mastitis, dairies can experience economic losses from treatment costs, lower production, increased labor, increased SCC and potentially removing a cow from the herd. Considering all of this adds up to the tune of $444 per one case of clinical mastitis1 and $100 per subclinical mastitis case1 , it’s time to raise the bar on mastitis detection and management. Obviously, there are many tried and true practices that combined with good management are effective at identifying and managing mastitis. So, what’s next… what are dairies doing to achieve higher levels of mastitis management? Four dairies share their insights on the benefits of incorporating mastitis polymerase chain reaction (PCR) testing into their management program.

Evergreen Dairy Farm, LLC

Kris and Carla Wardin, St. Johns, Mich.

550 cows, 29,500M, 74,000 SCC 2020 National Mastitis Council Gold Award 2019 National Mastitis Council Platinum Award

Seven Oaks Dairy, LLC

Tony Liebergen, Kaukauna, Wis.

1,100 cows, 29,800M, 125,000 SCC

Pagel’s Ponderosa Dairy, LLC

Chris Szydel, Kewaunee, Wis. 5,500 cows, 31,500M, 167,000 SCC

Country Aire Farms, LLC

Tom Gerrits, Greenleaf, Wis. 3,625 cows, 32,300M, 126,000 SCC 2020 National Mastitis Council Platinum Award

Why use Mastitis PCR testing?

Evergreen: We had purchased a significant number of animals for a herd expansion and had a substantial increase in our bulk tank SCC. We started with herd testing through our co-op, MMPA, and got our vet clinic involved when we did identify Staph aureus. Once we started monitoring through clinic cultures we had some difficulty collecting samples that were “clean” enough to get a valid culture rather than a contaminated result. When we started DHI testing to monitor individual cow SCC, we learned we could test those samples with PCR. We have continued to use it as a screening tool now that the Staph aureus infection rate is nearly zero. Seven Oaks: We typically average a 120,000-bulk tank SCC. It had been slowly creeping up and we knew we needed to do something. Around the same time, we were going through an expansion and Dr. Kelly Peters, our herd veterinarian, was getting nervous about all the new cows coming in. He suggested a new cow testing strategy to identify contagious mastitis using PCR. We tried it and had some come back positive for Staph aureus that we removed immediately. Initially we collected our own samples and took them to the lab. Now we rely solely on DHI collected samples. The convenience of CentralStar doing all the work and just giving us the information is extremely valuable. Pagel’s Ponderosa: We are aggressively tackling Mycoplasma bovis with a zero-tolerance approach. The PCR is hands down a better option than standard Mycoplasma culture because it is significantly faster. Because of our protocol to lockdown a positive pen until individual results are back, we need answers fast. The 48-hour turnaround time on PCR is significantly better than seven days for a Mycoplasma culture. Country Aire: We are always aiming to create a cleaner herd, keep bulk tank SCC low (goal under 100,000), and weed out non-profitable cows. We see the mastitis PCR as another tool for achieving and maintaining quality milk.

Evergreen: We were cautioned about the sensitivity of the test when we first started using PCR. We got advice on how to interpret results from our herd vet and Dr. Todd Byrem (former CentralStar Director of Research and Development). He helped us decide which organisms to focus on and how to utilize the Ct values to make management decisions. That was helpful because we had a fairly high prevalence of Staph aureus in the herd and needed to manage it aggressively to eliminate the issue. We now have an extremely low prevalence, so we do not pay much attention to Ct values. If a cow tests positive, it is marked in PCDART and she is monitored closely. While it is not a death sentence on its own, it becomes another ‘check’ against her so if other issues come up, we may be less likely to treat or keep her knowing she has that positive history. Seven Oaks: Every organism found for every cow gets recorded in BoviSync. This lets us build a substantial history for each cow so if something happens later with her, we can look back and have an idea of what may have led to the issue. It also helps us determine where mastitis pathogens are coming from. Sometimes it’s seasonal, sometimes it’s bedding management, etc. The data from PCR points us in the right direction. Pagel’s Ponderosa: Mycoplasma bovis is our top priority in terms of mastitis management. Any positive cow is removed from the herd. The benefit of the PCR finding live or dead organisms means she does not need to be shedding active organisms to find her. If she is carrying it at all, she is removed. We occasionally find Staph aureus with on-farm culture. When that happens, we send the sample to the lab to verify with PCR.

Country Aire: It’s helpful to watch the history of chronic cows and makes it easy to compare their results over time. We also recheck “good” cows to be sure they are truly positive for contagious mastitis before culling.

How is your vet involved?

Evergreen: The vets help to monitor the bulk tank culture results. When we first had more positive cows, the vet would advise us about options to manage those cows. Now that we have so few positives and an established protocol, the vet has less need to be questioned about the PCR results.

Seven Oaks: Our veterinarian helps to create the list of animals to be tested and sees all the results. He makes treatment recommendations based on those results.

Pagel’s Ponderosa: Dr. Don Niles is our on-farm veterinarian. He is actively involved in all herd health management decisions; mastitis is no different. Country Aire: Dr. Kelly Peters is the one who suggested the PCR to begin with. All results are sent to him, my son Craig, and I. We work together to make culling and treatment decisions based on results.

When is PCR a good option?

Evergreen: Anytime collection of aseptic

1Holland JK, Hadrich JC, Wolf CA, Lombard J. Economics of measuring costs due to mastitis-related milk loss. http://ageconsearch.umn. edu/bitstream/205638/2/AAEA%20Mastitis%20Paper-Final.pdf. Accessed Feb. 6, 2018. samples for culture is logistically an issue, PCR on DHI samples is a great solution. One hindrance can be the timing of DHI test intervals when dealing with a contagious outbreak. If your protocol is to test all fresh cows at each test, you could have a positive animal shedding for weeks before she is found because of the nature of DHI testing. If there is a major issue, owner-collected samples are a good alternative to use PCR more frequently. If a large number of cows need to be tested, it’s a much more labor efficient process, especially with pooled sample options. Seven Oaks: PCR is a good option through monthly DHI samples. This is the most convenient way to monitor new infections in the herd and what may be causing them. We all know mastitis can be caused by many different things. PCR helps narrow down where the issue is coming from. Pagel’s Ponderosa: PCR is a good option for any herd that has high milk quality standards. The PCR is a way to be sure the herd is clean. It provides fast results that allow a producer to make big management decisions. Country Aire: It’s another tool to manage milk quality. I see PCR on DHI samples as very valuable, especially for a herd size like mine. I get a monthly “picture of the contagious bugs” on my dairy. I fully intend to continue using mastitis PCR long term and would recommend it for any dairy working to improve or maintain their milk quality.

Michelle Kaufmann CentralStar Customer Solutions Advisor

PCR is a versatile tool for the detection of mastitis pathogens. Compared to traditional culture-based pathogen testing methods, PCR assays are as fast or faster with results available in 48 hours, and can identify multiple pathogens at one time, providing a road map to treatment and management. The PCR assay can be performed on DHI preserved milk samples and samples from treated cows. PCR saves time and labor for farms when conducted through routine DHI testing. PCR assays can be used in a variety of ways and management protocols.