MASTITIS SERIES: WHAT IS MASTITIS?

Summary

Mastitis is the most common disease in dairy cattle, costing New Zealand farmers an estimated $15,000 per herd each year. This inflammation of the udder, caused by bacterial infection, affects milk quality and cow welfare. Mastitis can be clinical, with visible signs, or subclinical, where the cow appears healthy but has high somatic cell counts. Effective management includes minimizing stress, maintaining hygiene, and using proper milking techniques. Seasonal strategies focus on early detection, reducing infection spread, and treating infections during the dry period. Understanding mastitis and implementing proper control measures is essential for maintaining milk production and quality.

Takeaways

• 😀 Mastitis is the most common disease in dairy cattle and can cost a typical New Zealand dairy herd around $15,000 annually in lost milk, treatments, and increased culling.
• 😀 Mastitis is caused by bacterial infections entering the udder through open teat ends, leading to inflammation and affecting milk production, quality, and cow welfare.
• 😀 The cow’s immune system uses white blood cells (somatic cells) to fight mastitis infections. Effective immunity depends on factors like stress levels, health, and environmental conditions.
• 😀 Clinical mastitis presents visible signs such as clots or flakes in milk, swelling, and pain. It’s more common in early lactation and is often caused by environmental bacteria like *Streptococcus uberis*.
• 😀 Subclinical mastitis doesn’t show visible symptoms but results in high somatic cell counts, affecting milk quality. It is often caused by contagious bacteria like *Staphylococcus aureus*.
• 😀 Good hygiene and stress management are crucial to prevent mastitis. Keeping teats clean and dry and minimizing environmental stressors help support the cow’s immune defense.
• 😀 Efficient milking techniques that don’t damage the teat duct or opening are essential for reducing mastitis risk. Quick closure of the teat end after milking is also important.
• 😀 Regular monitoring of somatic cell counts (SCC) helps detect mastitis early, even before visible symptoms appear, allowing for more effective treatment.
• 😀 During early lactation, mastitis control focuses on minimizing stress, practicing good hygiene, and managing individual cow health. In late lactation, controlling subclinical mastitis becomes more important.
• 😀 At dry-off and throughout the dry period, farmers can treat existing infections, cull unproductive cows, and prevent new infections to prepare cows for the next lactation cycle.

Q & A

What is mastitis, and why is it a major concern for dairy farmers?

Mastitis is the inflammation of the udder tissue in dairy cattle, typically caused by bacterial infections. It leads to significant financial losses for dairy farmers, with costs around $15,000 per year per average-sized New Zealand dairy herd due to lost milk production, increased treatments, and culling.

How does mastitis affect the cow's milk production and quality?

Mastitis causes inflammation in the udder, which can reduce milk production, lower milk quality, and harm the cow's welfare. Infected cows produce milk with higher somatic cell counts, which is a sign of infection and a key factor in milk quality decline.

What are somatic cells, and why are they important in mastitis diagnosis?

Somatic cells are white blood cells that the cow sends to fight infections in the udder. An increased number of somatic cells, measured in individual cows or the herd as a whole, is an indicator of mastitis presence and its severity.

What factors contribute to the cow's immune response in preventing mastitis?

A cow's immune response is more effective when the cow is well-fed, free from stressors like other diseases and poor weather, and kept in good overall health. Maintaining clean and dry teats and using efficient milking techniques also help support the cow's defenses.

What is the difference between clinical and subclinical mastitis?

Clinical mastitis is characterized by visible signs of infection such as clots or flakes in the milk, redness, swelling, or pain in the udder. Subclinical mastitis does not show visible signs but results in elevated somatic cell counts, which can go undiagnosed and worsen milk quality over time.

What are the common causes of clinical mastitis?

Clinical mastitis is often caused by environmental bacteria such as *Streptococcus uberis*. It is most common in early lactation and is associated with very high somatic cell counts.

What is the role of contagious bacteria in subclinical mastitis?

Contagious bacteria, such as *Staphylococcus aureus*, are the primary cause of subclinical mastitis. These bacteria are spread from cow to cow during milking, leading to high somatic cell counts even though no visible symptoms are present.

How does the timing of lactation affect mastitis occurrence?

Clinical mastitis is more common early in lactation, whereas subclinical mastitis tends to increase later in the season as production drops and cows become more susceptible to infection.

What are some strategies to manage mastitis on a New Zealand dairy farm?

Key strategies include minimizing stress, practicing good hygiene, early identification and treatment of mastitis cases, ensuring cows entering the milking shed have normal somatic cell counts, and focusing on milking technique later in lactation to prevent the spread of subclinical mastitis.

How can farmers control mastitis during the dry period?

During the dry period, farmers can cure existing infections, protect cows from new infections by controlling exposure to environmental bacteria, and remove cows or quarters unlikely to recover. This helps prepare cows for the next lactation season.