Controlling the bulk milk somatic cell count BMSCC is a problem common to many herds in later lactation.
All herds will experience a rise in BMSCC after December each year but the extent of this rise depends on the starting point. If the BMSCC is already high around peak lactation then the rise will be correspondingly high in the second half of the season. If the BMSCC is currently sitting around 300 or above then action is required now.
Firstly, keep teat spraying which means every cow after every milking for the rest of the season. Teat spraying reduces the new infection rate by 50% and herds with a high BMSCC will also have a higher than normal risk of infection during milking. Effective teat spraying will be achieved by the following:
Next identify the currently high SCC cows and decide on what to do with these by checking their age, previous history and other risk factors such as conformation and teat lesions. Young cows and cows that have had a case of clinical mastitis during the current lactation are worth treating. Any cows in this group with a strong positive to the RMT (‘3’) that can be best described as snot hanging from the tray regardless of history etc. should be treated as well. Cows with poor udder conformation and teat end lesions are less likely to respond to treatment and are candidates for drying-off early. Contact your vet for help with selecting the best treatment option.
Arguably the hardest decision is what to do with all the remaining moderately high SCC cows. In most herds, cows with a moderate RMT score are not worth treating during lactation. If there are low producing cows in this group it makes sense to dry them off early so they are no longer spreading the bugs around. Likewise, after pregnancy testing the empty high or moderately high SCC cows can be culled immediately rather than waiting, for the same reason.
By either treating or removing the worst cows from the supply the BMSCC should drop to more manageable levels. If not, then you are probably best to dry-off some of the remaining high to moderately high SCC cows ahead of the main herd to avoid grading issues later on. As a rule of thumb the lowest grading penalty is equivalent to 5% of the milk supply so work within the 5% range of the herd for early drying-off decisions.