Bovine mastitis refers to the inflammation of the mammary gland in dairy cows. It is one of the most economically important diseases affecting the dairy industry worldwide. The inflammation is commonly caused by bacterial infections, though physical or chemical injuries to the udder can also result in mastitis. Primary symptoms include abnormal milk, swelling or hardness of the udder, and general signs of illness in the cow. Left untreated, mastitis can seriously impact milk production and quality.
Causes and Risk Factors
The main cause of cow mastitis is bacterial infection of the udder. Common bacteria that cause mastitis include Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, and Escherichia coli. These bacteria usually enter the teat canal during or shortly after milking. Poor milking hygiene, overfilling the milking unit, and other milking management issues create opportunities for the bacteria to infect the udder. cows in late lactation or early lactation are also more susceptible due to anatomical and hormonal changes in the udder. Cows with damaged or unclean teats have a higher risk of infection. Housing and environmental factors like overcrowding, muddy lots, and contaminated bedding can spread infectious bacteria among cows. Physical injuries to the udder from trauma are another lesser cause of Bovine mastitis.
Effects on the Cow and Milk Production
Mastitis adversely impacts both the health of the dairy cow and milk production levels on the farm. Clinical mastitis causes systemic illness in the cow with fever, loss of appetite, and general lethargy. The infected udder becomes inflamed, red, painful, and swollen. Milk from an infected quarter appears abnormal, ranging from flaky to watery to purulent. Subclinical or hidden cases often do not cause visible signs of sickness but result in reduced and abnormal milk. Both clinical and subclinical mastitis lower milk yield per cow and decrease milk components like fat and protein. Severe or chronic mastitis can lead to permanent damage of mammary tissue and early removal of cows from the herd. The disease also increases susceptibility to other illnesses in cattle.
Economic Losses
Mastitis poses a huge economic burden on dairy farms worldwide. Direct costs arise from treatment expenses, discarded milk during therapy, premature culling of infected cows, and milk withholding periods. Indirect costs are difficult to quantify but huge, resulting from decreased milk production and quality as well as replacement heifer costs. Globally, mastitis is estimated to cost dairy farmers over $2 billion annually due to treatment, lost milk production, and premature deaths. Average losses per clinical mastitis case range from $180 to $250 in the United States. Subclinical or hidden cases are even more expensive due to their prolonged negative effect on milk yield. Mastitis reduces lifetime milk production of dairy cows by over 500 pounds, causing significant income losses over the production life of cows.
Control and Prevention
A comprehensive mastitis control program helps reduce the disease burden on farms. Thorough dry cow therapy with intramammary antibiotics provides protection during the non-lactating period before calving. Post-milking teat dipping or spraying with disinfectants helps control bacteria on teat skin surfaces. Ensuring a clean, dry, and well-ventilated environment prevents spread of environmental pathogens. Milking equipment should be properly functioning, cleaned, and sanitized between milkings. Proper milking hygiene requires pre-dipping teats, drying teats thoroughly, and post-dipping after completion. Reducing milking unit attachment errors and slow milking speeds lowers pressure on teats. Identifying and culling chronic subclinical cases prevents continued economic drain. Preventive techniques are far more cost-effective than treatment alone in controlling cow mastitis losses.
Genetic Selection and Vaccines
Selectively breeding dairy cattle for improved mastitis resistance also enhances herd health over successive generations. Breeding programs emphasize udders with low susceptibility to infection along with high milk production traits. Genetic testing identifies cattle best suited for further reproduction based on mastitis incidence and milk component levels. Vaccines against some mastitis-causing bacteria attempt to boost the cow's natural immune response to new infections. Though not 100% protective, vaccination combined with management decreases clinical episodes and subclinical infection rates on farms. Research continues to develop new generations of vaccines for multiple pathogens. As genetic, hygiene, and biologic control strategies progress in parallel, prospects are strong for significantly minimizing the disease burden of bovine mastitis worldwide.
Bovine mastitis remains one of the costliest conditions impacting dairy cattle health and global milk production levels. Effective control hinges on diligent adoption of hygienic practices during milking, proper environmental management, strategic dry cow therapy and vaccination, and genetic selection against mastitis susceptibility over time. An integrated approach combining management expertise with biomedical advances best supports dairy farmers worldwide in mitigating millions in potential economic losses from this inflammatory disease of the bovine mammary gland.
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