Two weeks before calving to two weeks after
The period around calving (from two weeks before calving until two weeks after calving) is the highest risk period for mastitis infections to occur. This period can be critical in determining the infection status of individual cows and the herd throughout the rest of the lactation. Therefore, milk quality for the whole season (or lactation) may depend on the success of mastitis control at calving. There are huge potential gains to be made by preventing new infections in the calving period and many of these infections can be prevented by implementing some relatively simple management changes.
Cows are very susceptible to infection around calving because their natural defence mechanisms are low. New infections occur, and subclinical infections which have persisted through the dry period may flare into clinical cases.
Around calving, the udder is often filled with milk for relatively long periods without the flushing effect of being milked. Bacteria may enter the end of the teat, particularly if high udder pressure opens the teat canals. They can then multiply and establish infections. High numbers of environmental mastitis bacteria may contaminate teats, especially if udders are wet and exposed to mud and manure.
Because of the high incidence of mastitis in the first month after calving, special care in this period will pay off.