Bulk tank somatic cell counts (BTSCC) have established themselves at an all-time low throughout the U.S. Michigan dairy producers are leading that charge with steadily declining BTSCC rates for the past 10 years.
BTSCC paints a healthy picture of milk quality, but leaves out an important piece of udder health. While less than 3 percent of U.S.-produced milk exceeded somatic cell count limits required for the export market (<400,000 cells/mL) in 2015, overall number of clinical mastitis cases is on the rise, growing from 15 percent in 1997 to 20 percent in 2015.
High clinical case rates are a consequence of more intense management, higher yielding cows in free stall barns with bedding that supports bacterial growth and exposure to environmental pathogens.
A 5 percent increase in frequency over almost 20 years may seem insignificant. But if 4 percent of a herd shows clinical mastitis monthly, that equates to 50 percent of the herd having clinical mastitis signs in a one-year period, according to Dr. Pamela Ruegg, DVM.
Ruegg is a professor and Extension milk quality specialist in the Department of Dairy Science at the University of Wisconsin and recently presented a roadmap to help producers achieve better results in the path to excellent udder health. Ruegg is originally from Michigan's Upper Peninsula and earned her undergraduate and DVM from Michigan State
University.
The bottom line is, low BTSCC score is a result of improved milking management and culling chronic cows and good contagious pathogen control. It doesn't always mean that mastitis is controlled.
One goal to reach for in controlling mastitis is 2 percent or fewer chronic cases monthly. "Achieving that goal is not the result of a single decision, but it is the cumulative result of many decisions," Ruegg said.
She recommends five top actions toward achieving the 2 percent goal and excelling in udder health.
The first step is culling chronic cows. All cows diagnosed with Mycoplasma bovis or chronic Staph aureus infections should be culled, along with cows with multiple infected quarters, older cows with a history of more than three monthly SCC tests above 200,000 cells per milliliter and cows that maintain a high SCC over two lactations.
The second action involves bedding choice and management.
Bedding choice studies show that sand-bedded cows continually outperform in terms of production and quality their colleagues bedded on mattresses and manure packs. In 325 studied herds, sand bedded cows produced 83.1 pounds per day while pack bedded cows averaged 78.1 pounds per day. BCSS on sand averaged 198,000 compared to 248,000 and cows with milk not sold averaged 1.6 percent compared to 2.4 percent. Mattress bedded cows fell between the sand and pack bedding methods. Ruegg believed the production yield difference was a direct result of decreased mastitis occurrence on the sand bedding. The studies also showed that sand bedded cows had a 2,542 pound greater rolling herd average and an additional $461 per cow income per lactation.
Both sand and organic bedding materials should be at least 75 percent dry matter. In loose housing, there should be 100 square feet of effective dry lying space per cow. Cows prefer dry lying area, and wet bedding of any variety will increase standing time. Dry lying space will also help repair hoof and reproductive problems. She strongly advises no greater than 15 percent overstock rate for free stall barns. Calving areas should be deeply bedded and dry.
"If you would feel uncomfortable laying in the calving area yourself, then you need more bedding," Ruegg said.
Her third action requires developing and keeping a professional work force and training them to excel in udder health. A posted milking routine in an appropriate language and reviewing the procedures monthly results in lower rates of clinical mastitis.
Fourth, antibiotics should only be used on cows that will benefit. Ruegg suggests that only 40 percent to 50 percent of cases will benefit from antibiotic therapy.
Antibiotic residues are declining, the consuming public has a general perception that farmers are overusing antibiotics. Ruegg asks, "Can we defend all antibiotic uses if only half of the cases will respond to treatment?"
When possible, she says it pays to determine the bacteria variety and treat with a drug that will kill the pathogen. Read and follow all labeled instructions.
Finally, she said to think about eating lamb. Associating the adorable face of a baby lamb with a lamb chop is enough deterrent to turn some consumers away from enjoying the meat. In the same manner, are mental associations a consumer may have toward dairy farms or products enough to turn them away from an entire food group?
"Are you confident that you can defend all of your management and drug use practices to the non-farm public?" Ruegg said. "If not, what can you do to change practices?"