In September the USDA Animal and Plant Health Inspection Service (APHIS),National Animal Health Monitoring System (NAHMS) released information on 2011 bulk tank somatic cell counts (SCCs) from four of the 10 Federal Milk Marketing Orders. The bottom line of the report is that bulk tank somatic cell counts (BTSCCs) continue to decline. Overall, BTSCCs have decreased every year since 2007.
There are a number of reasons why BTSCC values continue to fall, says Pam Ruegg, DVM, MPVM, University of Wisconsin. “One of the reasons is that producers are more aware of the importance that processors place on producing milk that is of high quality,” she explains. “I think that the continued emphasis on improving quality resonates with many producers.”
Jason Lombard, DVM, MS, USDAAPHIS Veterinary Services, Fort Collins, Colo., adds that in some places, quality bonuses may play a role in reducing SCC. “I know that processors have essentially implemented the 400,000 limit since they don’t want to have to segregate milk that can’t go the European Union,” he says.
However, Ruegg thinks there are other important reasons that SCC has been decreasing. “Many of the best management practices that have been long recommended and are known to reduce mastitis and improve milk quality are now highly adopted and almost seen as just standard procedures on most dairy farms,” she says. “For example, virtually everyone uses pre- and post-milking teat disinfection, most conventional farmers administer dry cow treatments to every quarter of every cow at the end of every lactation, and most cows are milked using modern milking equipment that is serviced on a regular basis.” Ruegg says that we also continue to see more consistency in milking routines and most cows today are probably milked with some version of the strip, dip, dry, apply procedure. “Finally, the rapid expansion of many dairy farms and the resulting reduced age of the average cow on those farms is advantageous to producing milk that has lower SCC because younger cows typically have less chronic mastitis infections.”
Size of farm may also play a role, Lombard says, likely due to the factors Ruegg mentions above. “Larger farms have consistently lower cell counts and as the percentage of large farms increase and since they represent most of the dairy cows, SCC decreases,” Lombard notes.
50% between 200-400k
The USDA report says almost 50% of shipments had BTSCCs between 200,000-399,000 cells/mL. Both Ruegg and Lombard believe producers will be able to increase this percentage of low SCC milk.
“I believe that this percentage will increase and that the number of producers who are shipping low SCC milk will continue to grow,” Ruegg says. “Following the NMC 10-point mastitis control plan, having goals for milk quality and implementing an annual udder health plan are all actions that farmers can take to continue to make progress.” (See sidebar below).
“The trend is clear and has been consistent,” Lombard says. “There has been a slow and steady rise in the percentage of milk below 400,000. I think adoption of best management practices listed above will be necessary for producers to meet the processor-implemented limits.”
Though the National Conference on Interstate Milk Shipments decided not to lower the U.S. SCC limit from 750,000 cells/mL to 400,000 cells/mL, Lombard and Ruegg believe that could change if producers continue to reduce SCCs. “With 10% of milk being exported, countries will continue to ‘assist’ the U.S.in adopting lower limits,” Lombard notes.
Veterinarians play a role
Getting clients to implement processes that lower SCCs offers opportunities for veterinarians to help clients get and keep on the right track. “Low hanging fruit for improving SCC on most dairy farms is identifying and making individual cow decisions about cows with chronic subclinical mastitis infections,” Ruegg says.
“There are really only six decisions that can be made with these cows and for each chronically infected cow, the management team should decide which of these six options is most appropriate based on the type of pathogen that is causing the infection,” Ruegg explains.
These six decisions are:
1) cull the cow
2) dry off the quarter
3) dry off the cow
4) treat the quarter
5) segregate the cow
6) use a quarter milker to discard the milk
It’s not just getting clients on board with more intense programs that decrease SCC, but helping them maintain those levels despite seasonal fluctuations such as summer heat and humidity is an area where veterinarians can have a real impact.
Bulk tank SCC values increase in summer because heat and humidity are the exact conditions that favor the growth of mastitis pathogens. Cows are often cooled using water and exposure to water is always a risk factor for the development of mastitis. “Part of an annual udder health plan should be focused on maintaining udder health throughout the high risk periods when cows are exposed to heat stress,” Ruegg recommends.
Lombard adds on larger farms with more employees, continued worker training is key to keep them focused on correct protocols – training that can be provided, monitored and evaluated by the herd’s veterinarian.
On some farms, facilities are limited and it can be difficult to reduce exposure to environmental pathogens. “In these herds, we really need to look hard at identifying the highest risk cows and making sure that they are managed in the best possible manner,” Ruegg says.
To view the “Determining U.S. Milk Quality Using Bulk-tank Somatic Cell Counts, 2011” infosheet, visit http://tinyurl.com/cwahgou. Visit the NAHMS website at http://www.aphis.usda.gov/animal_health/nahms/.
What the 2011 U.S. bul k-tank SCC report showed
• More than 99% of milk and 98% of shipments monitored met the current PMO limit of 750,000 cells/mL.
• Of the 29,937 producers, 92.3% (all but 2,305) shipped milk with BTSCCs below 750,000 cells/mL during all months monitored.
• During all monitored months, BTSCCs in 92.7% of milk was less than 400,000 cells/mL.
• Only 53.6% of producers shipped milk below 400,000 for the entire year.
• In 2011, almost 80% of shipments had BTSCCs below 400,000 cells/mL.
10-point mastitis control plan
The NMC Recommended 10-Point Mastitis control plan is available as a pdf checklist on the NMC website at http://nmconline.org/docs/NMCchecklistNA.pdf.
The 10 categories featured in the plan are:
1.Establishment of goals for udder health
2.Maintenance of a clean,dry, comfortable environment
3.Proper milking procedures
4.Proper maintenance and use of milking equipment
5.Good record keeping
6.Appropriate management of clinical mastitis during lactation
7.Effective dry cow management
8.Maintenance of biosecurity for contagious pathogens and marketing of chronically infected cows
9.Regular monitoring of udder health status
10.Periodic review of mastitis control program