You may have heard that leaving milk in the udder leads to more mastitis, affects milk quality and lowers milk production. For many years, we thought removing all the milk at every milking was the right thing to do.
The positive results of strategies such as maximum milking time (MaxT) or changing automatic cup remover (ACR) settings to remove cups at a higher milk flow rate has been confronting to these views. But many farmers have discovered that strategies to reduce cow milking times and increase milking efficiency are also good for udder health.
What does the research show us?
In New Zealand, trials in the 2010s reported on the effects of MaxT or raising the ACR thresholds, for cows milked twice daily and with low somatic cell counts (SCC). Results showed no increase in mastitis or decrease in milk production, even when more than 0.7 litres of milk was left in the udder in some cases.
Similar results were observed in Australia, where researchers concluded that incomplete milking (in their case leaving behind 0.5 litres) had no effect on SCC even for cows with mild, subclinical mastitis. That means cows with a higher SCC shouldn’t prevent farmers from using strategies to improve their milking efficiency.
What about gross under-milking?
Two international studies have explored the effects of gross under-milking for high-yielding cows, milked twice daily. In France, researchers found little impact on milk volume or SCC even if 30 percent of the milk volume was left in the udder at a single milking. But when comparing udders with both fully milked glands and ones with 25 percent of the milk left behind at each milking, researchers in America found some depression in milk production, and a doubling of the SCC over a six-week period.
Both studies led to much greater volumes of milk retained in the udder after milking compared with MaxT; neither reported increases in the risk of mastitis
Myth: Incomplete milking leads to mastitis.
Busted: A moderate level of incomplete milking (e.g. strip yields of up to one litre of milk per udder) does not increase the risk of mastitis or SCC.
What is SmartSAMM
SmartSAMM is all about using a Smart and Seasonal Approach to Minimise Mastitis. It provides tools and resources to help dairy farmers and advisers better manage mastitis and milk quality. It covers everything from what mastitis is and why it's important, to the best ways to manage it on a seasonal basis and where to get help.
Find out more at dairynz.co.nz/mastitis
This article was originally published in Inside Dairy October 2019