2024/2025 has turned out to be a long season: with many of you planning to milk well into May. But this can come with some challenges. Late lactation clinical mastitis and subclinical mastitis can be difficult to manage. Many farms can experience an increase in bulk tank somatic cell count towards the end of the season as cows start to produce less milk. This means there’s less milk volume to dilute out the number of somatic cells in the bulk milk tank.

Somatic cells are immune cells, and they can increase due to new intra-mammary infections in late lactation. Sometimes a rise in bulk tank somatic cell count can be related to nutritional or other stress factors in late lactation – and often this will go hand in hand with a large number of clinical cases. If a clinical mastitis case is undetected in the main herd, it will markedly increase the bulk tank somatic cell count.

The late lactation treatment difficulties:

Late lactation mastitis can be more difficult to treat with lactation cow therapy. A late-season milk sampling case will let you know what type of mastitis bug you’re dealing with and whether it’ll be difficult to treat. Cows with high somatic cell counts (over 200,000 cells) in late lactation that have had repeated high cell counts throughout the season, have had more than 2-3 cases of clinical mastitis, and are over 7 years old, should be seriously considered for culling.  A prolonged course of antibiotics in the form of dry cow therapy may be enough to cure these cows, so they can come back into the herd for the new season with a low somatic cell count.  Often, farmers who ‘hang onto’ these problem cows year after year and have a lax culling policy will end up with more mastitis (subclinical and clinical) – as these problem cows act as a source of infection for the rest of the herd.

Drying off high cell count and problem cows earlier than the main herd may keep your bulk milk in check for longer. A strict culling policy and prompt treatment of any clinical cows is also recommended.

For more information and advice, or help with updating dry off lists and selection choices of cows to cull: talk with your vet or one of Anexa’s advanced mastitis vets.