Mastitis is an inflammation of the mammary gland that has big negative effects on the health and income of dairy cows. Mastitis is seen as a bad sign of well-being because it can cause pain and discomfort. It is most often caused by pathogens like Staphylococcus aureus, Streptococcus uberis, and Escherichia coli taking over and living in the mammary gland.
Subclinical mastitis is when an infection is present but there are no obvious signs of local inflammation or involvement of the whole body. Clinical mastitis is an inflammatory response to an infection that changes the shape of the udder, changes the way the milk tastes, and raises the number of somatic cells.
How mastitis affects the economy
Mastitis has direct economic costs, such as a drop in milk production and quality, a change in the way milk is made, a shorter life span for affected cows, higher veterinary costs, milk that is thrown away during treatment, somatic cell count penalties, a higher chance of early culling, and less fertility.
Mastitis is thought to cost the dairy industry worldwide between $19.7 and $32 billion each year. The cost of subclinical mastitis depends on how many cows have a high number of somatic cells and how much milk production is lost, which is expected to be more than $1 billion per year in the US.
Rumen microbiota
The rumen is an anaerobic and methanogenic fermentation chamber containing a community of microorganisms such as bacteria, archaea, protozoa, and fungi that utilise cellulolytic feeds. The rumen microbiota has a lot of different kinds of organisms and a lot of different kinds of interactions between them.
In the rumen, there are three small environments. 25% of the microbial mass is in the liquid phase, 70% is in the solid phase, and 5% is made up of rumen epithelial cells and protozoa.
Subacute ruminal acidosis in dairy cows
When dairy cows have subacute ruminal acidosis, milk fat, milk protein, the ratio of fat to protein, and dry matter all go down. However, milk urea nitrogen goes up. Also, dairy cows that have had subacute ruminal acidosis have a higher number of somatic cells, serum amyloid A, and proinflammatory cytokines, all of which are signs of mastitis. Also, cows have a high inflammation score, a lot of inflammatory cells in the alveolar wall, destruction of the mammary glands, and thickening of the alveolar wall.
The blood-milk barrier is a specific structure that stops things from the blood or outside environment from getting into the mammary gland. Subacute ruminal acidosis changes the structure and function of the barrier between the blood and milk and makes both the blood and milk make more immunoglobulins. On the other hand, lipopolysaccharide is an important inflammatory substance that gets into the mammary gland through the blood, breaks down the barrier between the blood and milk, and causes the mammary gland to become inflamed in dairy cows.
Subacute ruminal acidosis makes the rumen and intestinal barrier more permeable, which makes lipopolysaccharide from the rumen leak into the bloodstream. Also, milk and rumen fluid from cows with subacute ruminal acidosis have less bacteria than milk and rumen fluid from healthy cows.
Conclusion
Mastitis is one of the most important economic and animal welfare problems in the dairy cattle industry around the world. Mastitis is a disease that has more than one cause. The environment, the pathogens, and the host all play a role. Due to subacute ruminal acidosis, an imbalance in the rumen’s microbiota can cause a dairy cow to get mastitis. More research is needed to find ways to balance the microbiota in the rumen through nutrition, which would reduce the number of cases of mastitis.
