Preventing disease is a main concern for many dairy farmers. Because mastitis is among the most common infections in the dairy industry, producers should be aware of the danger it poses to the health of their animals and the safety of their milk.
Mastitis, an inflammation in the mammary gland, is caused when pathogenic bacteria enters a cow’s udder through the teat orifice, moves into the teat canal and causes an infection.
A cow’s somatic cell count (SCC), the number of white blood cells produced, provides an indication of the degree of mastitis in an individual cow because a cow’s body will produce the white blood cells to fight inflammation in the mammary gland.
Jodie Pennington, dairy specialist at the University of Arkansas Cooperative Extension Service, said an inflammation of the mammary gland may result in clinical mastitis with varying degrees of visible signs of the disease or subclinical mastitis where no visible symptoms occur.
“Monitoring SCC is especially critical in diagnosing cows with subclinical mastitis since the producer is unable to see the visible signs,” Pennington said.
He said the most common methods of monitoring SCC in bulk tank milk are actual SCC from the health department or milk plant and the Wisconsin Mastitis Test (WMT). In an individual cow, the actual SCC or linear SCC score from Dairy Herd Improvement (DHI) records and cow-side tests such as the California Mastitis Test (CMT) indicate SCC. Also, some milk processing plants will measure SCC on samples of milk from individual cows.
“It is important for producers to monitor the SCC in their cows because federal law allows milk to be sold only if the bulk tank has a SCC of less than 750,000/ml. The primary reason for dairy producers to reduce SCC is because it relates to milk losses due to mastitis,” he said. “If they can reduce their SCC from 600,000 to 200,000 cells/ml, they can decrease milk production losses by 600 pounds per cow per year.”
Pennington said producers have two options to reduce SCC in a herd.
“The first method, culling infected cows, is a short-term solution that can quickly reduce SCC in the bulk tank,” he said. “The second method, controlling mastitis, is a long-term solution that should be the basis of a sound management program. The most economical method to determine SCC is testing monthly milk samples from each cow.”
Pennington suggested monitoring each cow monthly with SCC from DHI records for a mastitis prevention program and following a proper and sanitary milking procedure with proper equipment.
Johnny Gunsaulis, University of Arkansas Extension agriculture specialist, said sanitation and stress management are also methods for preventing high SCC and the onset of mastitis.
“Sanitation is a big key in reducing mastitis, and we're much more likely to get into problems during the wet weather,” he said. “Sanitation around the parlor and holding areas, in addition to moving animals to fresh pastures whenever possible, should help reduce the incidence of the disease.”
Gunsaulis said reducing irritations will also help. Stray voltage is the damaging electricity that can be grounded through a cow in the dairy barn and causes the cow to produce epinephrine. The production of this hormone prevents the removal of all of the cow’s milk and can lead to a bacterial infection. He also said improper pulsation on milking equipment can lead to mastitis problems.
