Pre- and post-milking teat disinfection, dry cow treatments to every quarter of every cow at the end of lactation and the use of modern, well-serviced milking equipment have contributed to lower SCCs. 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.