Constructing udder health plan
It's a new year and a great time for dairy farmers to put together an annual udder health plan.
A sensible plan makes cents. "It is always more cost-effective to prevent mastitis than to treat mastitis," Dr. Pamela Ruegg said during "Using Key Performance Indicators To Manage Udder Health," the second segment of "Healthy Udders, Optimal Milk," a World Class Webinar being presented by Professional Dairy Producers of Wisconsin.
When dealing with animal health data in general and mastitis information in particular, dairy farmers must spend some time figuring out how and if the information being gathered can be trusted or used to make good decisions.
Fortunately, there are critical key performance indicators that can help assess which changes on the farm can improve udder health, Ruegg said.
While a whole list of items are in play, ranging from milking routines and milking systems to dry cow programs, studies have shown that no one individual farm practice is independently related to milk quality.
"These things are intertwined and the ability to improve milk quality is associated with developing a way to assess and improve many things on the farm in a systematic way," Ruegg said.
With that in mind, she strongly encourages every dairy farm to develop an annual udder health plan.
A typical plan details goals for udder health, assigns actions for people to try to achieve those goals and sets timelines for when the actions will be assessed to see if progress is being made. Regular meetings between consultants, managers and key farm workers can be used to review the progress.
Improving milk quality requires managerial skills, Ruegg said, particularly the ability to assess the current situation, develop goals for improving and reducing mastitis, implement and measure the actions, assign responsibility, determine the results and identify the next step.
"This requires records, data, regular planned time for management and effective monitoring systems," she said.
It is key to understand that mastitis is a disease of individual cows, but mastitis prevention and control programs are applied to the herd, Ruegg said. They require effective detection of clinical and subclinical mastitis, accurate diagnosis of the pathogen involved, a way to evaluate treatments and implementation of herd specific preventative practices.
Effective surveillance for mastitis must include standardized definition and detection systems for subclinical mastitis and clinical mastitis. Ruegg advised using a recording system to identify risk factors for new infections and having feedback so the managers and veterinarians working on the udder health plan can assess the current situation and make recommendations.
"One of the big questions we need to answer is how much mastitis is occurring on the farm - how much clinical mastitis and how much subclinical mastitis," Ruegg said.
Mastitis is a very simple disease — a bacterial infection of the udder with two presentations. For subclinical mastitis, the important monitor is individual cow somatic cell counts (SCC). Clinical mastitis, which presents as visual abnormalities of the milk and udder, is more problematic to measure and compare among farms since definitions and detection efforts vary, Ruegg noted.
A critical first step is training workers to detect and record mastitis in the parlor. "Make sure there aren't any negative consequences for milkers who report mastitis, and make sure the definitions are the same for the milkers, the farm manager and the vet," Ruegg advised.
When monitoring clinical mastitis, she encourages efforts to systematically record the data in a way that's useful for analysis in order to determine the actual clinical case rate.
"If we're looking at developing an assessment plan, the most critical thing to know is not how many cases, but how many new cases are occurring each month," she said.
Monitor recurring cases separately, monitor what portion of cases are severe and know what the most common bacterial culprits are, Ruegg advised.
Given every dairy farm should be recording clinical mastitis cases and recording the severity of each case, Ruegg recommended a simple system that details the date, the cow, the quarter involved and a severity score of #1 (mild) for when only the milk is abnormal (detected by forestripping); #2 (moderate) for abnormal milk and abnormal udder; and #3 (severe) for abnormal milk and a sick cow.
Data drawn from hundreds of Wisconsin farms suggests that approximately 50 percent of a farm's cases should present as #1, about 35 percent should be #2 and between 5-15 percent should be #3, Ruegg noted.
KPIs to tackle mastitis
Ruegg shared the top three most important key performance indicators for udder health, which feature goals gleaned from data from 45 large Wisconsin dairy herds. "These goals are achievable and are being achieved on many Wisconsin dairy farms," she pointed out.
Every farm should record the incidence of first cases of mastitis, calculated by dividing the number of first cases by the average number of currently lactating cows. The goal is less than 25 cases per 100 cows per year. The very top herds had less than 15 cases per 100 cows, she noted.
Every farm should also be recording the proportion of cows with not sold milk, calculated by dividing the number of cows whose milk was discarded by the average number of milking cows. The figure should be less than 1.5 - 1.6 percent of the herd.
The third most important indicator is the proportion of cows with mastitis that have a second case within 90 days of the first case. The goal is less than 25 percent of first cases with a second case within 90 days. For the top herds, recurrence rates were between 5-10 percent.
In addition, dairy producers might want to monitor the proportion of cows that have more than one quarter clinically affected. If that rises over 20 percent, Ruegg said, she would start looking for mycoplasma.
She would also look at the number of cows milking on less than four quarters, which should be less than 5 percent.
KPIs for subclinical mastitis
Since somatic cells in the milk indicate infections, Ruegg stressed that it is extremely important to monitor the counts in order to detect subclinical mastitis and improve udder health. "If we don't have individual cow somatic cell count data, we simply can't manage this disease," she said.
"Many, many mastitis infections remain subclinical for long periods of time," she said. "Clinical episodes are the tip of the mastitis iceberg."
The key management questions for subclinical mastitis include what is the prevalence of cows with SCC over 200,000 and what is the incidence rate of cows going over 200,000 for the first time in the lactation.
Another question, considered very important from an economic and a production standpoint, is what proportion of cows have subclinical mastitis at the first DHIA test after calving. That's because the earlier in lactation that cows develop into infection, the bigger the impact on productivity, milk yield, risk of clinical cases and the probability that they may become chronic, lose the quarter or infect other cows in the herd, Ruegg explained.
The KPI recommended by Ruegg are the prevalence of subclinical mastitis, indicated by the proportion of cows above 200,00. The goal is less than 15 percent of the lactating cows.
The incidence or new infection rate is the number of cows with SCC greater than 200,000 for the first time in the current month, divided by the number of cows below that level in the previous period. The goal for new infection rates is typically between 5-8 percent.
The prevalence of subclinical mastitis at first DHIA test, meaning cows with a SCC above 200,000, should be less than 5 percent of the first lactation animals and less than 10 percent of older cows, which Ruegg agreed was aggressive.
Another "really important" key performance indicator is the prevalence of subclinical mastitis at the last DHIA test before dry off should be less than 30 percent of the cows. "If we know the beginning and the end, we can make a pretty good assessment about what's going on in between," Ruegg noted.
Also, the proportion of chronic mastitis over the dry period should be measured with a goal of less than 10 percent.
"That cow, the one that's always above 200,000, should be leaving the herd, so there shouldn't be that many of these cows. In most cases, they're costing you a lot more money than they're making you," Ruegg said, underscoring the importance of monitoring to prevent chronic cows.
"So we've got all these key performance indicators that we can use to monitor udder health, but really the thing that we want to do is have farms and goals and plans to reach those goals that are done in consultation with the advisors on the farm," Ruegg concluded.
For more information, visit the UW milk quality website at milkquality.wisc.edu.