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5-Step SCC Reduction Approach
Excerpt from presentation at the NMC 2020 Annual Meeting. Peter Edmondson, UdderWise Ltd., United Kingdom
The telltale signs of clinical mastitis are changes to the milk, such as clots, abnormal color and/or consistency, and there may also be udder swelling, heat, hardness, redness or pain – depending on severity. Bottom line: it is easy to detect.
On the other hand, subclinical mastitis “hides” physical symptoms and is not visible to the naked eye. In general, subclinical mastitis can only be detected by sampling and testing milk.
High SCC impairs yields
Contagious mastitis mainly causes subclinical infection resulting in raised SCC, explained Peter Edmondson at the 2020 National Mastitis Council Annual Meeting. “High cell counts are undesirable as they have negative effects on milk quality, shelf life and manufacturing yield.”
As a global milk quality consultant, Edmondson advises dairy producers managing a wide variety of dairy herds in a multitude of milking systems and housing environments. Yet, he sticks to five basics as he helps dairy producers improve milk quality. He said his approach has always been successful – “so long as the farmer engages in the process and that requires effective communication and understanding of the disease (mastitis) and the process.”
5 STEPS TO BETTER QUALITY MILK
1. Identify high SCC cows
Rely on three sets of SCC data to accurately assess an individual cow’s infection status. Collect a representative milk sample. Discard foremilk and collect an equal volume of
milk from each quarter. Edmondson noted that most modern milking parlors include a sampling port, which makes milk sampling an easy task.
The best way to evaluate milk quality is to
test milk via a milk recording program, such
as Dairy Herd Improvement (DHI). Typically, milk is tested monthly. “These programs return data in a useful format that will show a range of information for each cow, including the percentage contribution to the bulk tank SCC on test day,” said Edmondson. “They also give a useful herd summary.”
A third testing option is the California Mastitis Test (CMT). This test works in countries that don’t have access to a milk testing laboratory or equipment. Edmondson noted that CMT – a crude cowside test – is useful but leaves a lot of room for interpretation. Operator analysis varies significantly. “It (CMT) does not give a
"The best way to evaluate milk
quality is to test milk via a milk recording program, such as Dairy Herd Improvement (DHI)."
numerical result and most changes are seen when SCC is more than 400,000 cells/ml,” Edmondson explained.
2. Minimize spread of infection
Conduct a complete assessment of mastitis management to minimize spread of infection. Edmondson provided a list of key steps.
If high bulk tank SCC challenges a herd, form a high SCC cow group. This group should be milked last to reduce spreading infection to low SCC cows.
Wear clean gloves throughout milking. Most milkers’ hands are contaminated with mastitis organisms when they milk without gloves.
Use one cloth or paper towel per cow for drying teats. When using cloth towels, wash and dry them at a high temperature. After 500 to 600 milkings, discard cloth towels.
Detect clinical mastitis by stripping out a few squirts of foremilk and then follow the farm mastitis treatment protocol. Ideally,
all treated cows are milked last to avoid cross contamination among cows and to avoid medicine residues entering bulk milk. Forestripping also stimulates milk letdown.
Disinfect each teat (entire surface) with a quality post teat disinfectant after milking. “Post dipping reduces the new infection rate by around 50 percent,” said Edmondson.
Change milking machine liners (inflations)
as recommended by the manufacturer. After every milking, traces of milk remain on the liner, which may contain bacteria. Transmission risk increases with worn liners.
Train farm staff on an ongoing basis to ensure they follow standard operating milking procedures. Share key performance indicators with your staff and engage them in mastitis control and praise good work. “A simple whiteboard with basic mastitis data can be invaluable,” Edmondson commented.
3. Implement bacteriology testing
Identify which bacteria are responsible for subclinical mastitis. Collect milk samples from cows with high SCC. These cows should represent different ages and chronic and recent mastitis infections.
“Bacteriology testing is essential when making decisions about problem cows,” Edmondson stated.
4. Implement a decision-making tree regarding high SCC cows
After making a concerted effort implementing steps one through three, focus on cows contributing the highest percentage of somatic cells to the bulk tank. During
the decision-making process, consider percentage contribution to the bulk tank, individual SCC history, age, response to previous antibiotic dry cow therapy, clinical mastitis history, milk production, fertility status, locomotion or lameness problems, health and temperament issues.
Provide antibiotic dry cow therapy to mastitis- infected cows. Consider culling cows with chronic high SCC. “Culling is expensive
and irreversible; it’s important to get these decisions right,” said Edmondson.
Other options for dealing with high SCC include drying off cows early, drying off individual quarters, discarding milk (e.g., feed milk to calves) and antimicrobial treatment during lactation. “The only microorganism that responds well to treatment during lactation
is Strep. agalactiae,” Edmondson explained. “Treatment success for chronic Staph. aureus and Streptococcus uberis infections is generally disappointing. “Discuss treatment options with your veterinarian to see if treatment during lactation is appropriate.”
5. Monitor milk quality progress
Edmondson commented that it takes about one year before seeing significant herd SCC reduction – assuming the listed control measures were followed. Review all mastitis control measures if the bulk tank SCC is not falling. “There is no reason why every herd cannot reduce their cell count to less than 150,000 cells/ml by following this approach,” he concluded.
Article from National Mastitis Council, September, 2020
CHRISTMAS 2020 ❆ BC HOLSTEIN NEWS 25
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