Beat Mastitis With Records

An Udder Health Management package adds a new tool to help prevent future mastitis infections. By Dave Natzke

Can a DHI report prevent mastitis infections? Ron Curran, AgSource Cooperative Services manager of market development, believes it can.”Typically, most producers use SCC information for treatment and culling,” Curran said. “This is an expensive and ineffective way to fight mastitis problems.”
AgSource’s Udder Health Management (UHM) Package, including a UHM Summary (Figure 1) and UHM Cow Report (Figure 2), provides a new approach to udder health management and mastitis prevention.
“These reports provide a sensitive and accurate tripwire to let you know when and where problems are,” Curran explained. “Combining these reports with milk culturing gives you some powerful tools to prevent future infections.”
By the time a noticeable rise in a herd’s bulk tank SCC is seen, the opportunity for early intervention is missed and an infection can become entrenched. Once established, mastitis is a menacing disease that can take years to bring under control. Preventing infection establishment underscores the value of early detection. Early and accurate signals are equally important for knowing when things are improving. Using the new reports, the dairy management team can determine a herd’s subclinical mastitis profile, trends and the effects of recent management changes.
Throughout the reports, a cow is considered subclinically infected if her SCC is equal to or greater than 200,000 cells/milliliter. Risk groups are color coded throughout both reports to match the Udder Infection Summary areas, making it easy to track problems. The darker blue area represents fresh cow infections (5-40 days in milk, or DIM); the light blue area indicates new infections occurring after the first 40 DIM. The burgundy area quantifies the number of chronic infections (two or more consecutive tests, including the current one, equal or grater than 200,000). The most recent test day is on the right.
For this example herd, the Risk Group Analysis graph (in Figure 1) makes it easy to see infections have dropped over the past year, and new infections have dropped over the past two months.
The new infection rate is the most important number to monitor on the whole report, Curran said. If this number is equal to or greater than 20%, the producer should take immediate action to identify the cause of the new infections.
Previously, AgSource’s udder health management report defined new infection rates by dividing the number of cows having their first SCC test this lactation > 200,000 by the number of cows on test that month. Cows coded as “Condition Affecting Record (CAR)” were not included, even though many of these cows were off their usual production because they were sick, perhaps due to mastitis infections.
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The new report does not ignore the dynamics of previously infected cows that later dropped below 200,000 SCC. Consequently, the new report categorizes new infections as any cow equal or greater to 200,000 this test whose previous milking test day SCC was less than 200,000. The denominator reflects an “at risk group,” including only uninfected cows on the previous test day. CAR cows are also included.
Infection rate example
Milking cows on test day 100
Cows with new infections 10*
(have been infected earlier in this lactation)
Cows with new infections 15
(first time this lactation)
Chronically infected cows 30
New infection rate
Using the old/ conventional way 10/100 or 10%
New methodology 25/70 or 36%

* two of these cows were coded as “Condition Affecting Record” or CAR

The report’s New Infection Rate is a better reflection of this herd’s udder infection status. To make the calculation more accurate, if a cow’s first test after calving is equal to or greater than 200,000 SCC, AgSource goes back to the last test of her previous lactation. If she was infected then, she is not a new fresh cow infection; she is a chronic infection. This may help head off wasting time and money trying to correct a fresh cow new infection problem that was actually an incurable chronic mastitis issue.
From herd level to cow level
While the UHM Summary gives an overview of the herd, the UHM Cow Report provides detailed information on individual cows.
“The UHM Summary is a herd or group management tool to identify problems,” Curran explained. “To take problem solving to the next level and identify solutions, you need to get to the cow level.”
Using the same color coding as the UHM Summary, the UHM Cow Report divides all subclinically infected cows into the same groupings.
Producers can then identify the cows contributing to the rise in herd chronic infections. Pat Baier, AgSource vice president of DHI Operations adds, “We removed the ‘Predicted % SCC Contribution to Bulk’ column, what everyone called the ‘Hot Cow List’, and put it on the Chronic Cow List (see Figure 2) to help prevent members from making decisions based on one high SCC test. High SCC values move around a lot, and by putting the ‘% Contribution’ column in the Chronic Cow List, users get more complete information on chronically infected cows.”
The Chronic Cow List provides valuable information to help identify which cows to cull; reproductive status; production ranking in the herd; present production; DIM; and a summary of subclinical infections over the last two lactations. An additional benefit: the UHM Cow List makes it easy to pick the right cows to culture. Cows in the Fresh and Lactating Cow New Infection Lists and Response to New Infection List (see Figure 3) are excellent candidates for culturing for two reasons, Curran said. First, culturing chronic cows provides bacteriological information with lots of lag time; new infection cultures profile the most recent causes of infections. Second, the possibility of using culture results for successful treatment is much higher in new infections compared to chronically infected cows. Culturing information narrows the solutions you need to focus on:
1) If results point predominantly to environmental infections, the goal is to protect the cow’s teat end from being overwhelmed by bacteria and to make sure teat dip covers the entire teat end.
2) If infectious mastitis predominates, have your milking equipment checked by a technician during milking and follow their recommendations. Also, be ready to overhaul your herd‚Äôs milking technique and specifically udder preparation. Again, make sure teat dip covers the entire teat end. Consider culturing all cows with an SCC >200,000 to identify cows infected with these “cow-to-cow” infections and consider grouping them so they are milked last. “After implementing these steps, monitor “New Infection Rates.” If they start dropping, keep doing what you are. If they aren’t, develop and implement a Plan B, Curran advised
Contact Ron Curran, AgSource Cooperative Services’ manager of market development, phone:
608-845-1900 ext. 5219, or e-mail: rcurran@agsource.com.

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