National study highlights cluster hygiene value
With herds ranging from less than 60 to more than 960 cows and yields from under 4500 to over 12,000 litres/cow, they were selected to provide a good cross-section of current dairy management practice.
The vast majority milk in herringbone parlours, with 8% having rotaries and 5% the latest automatic milking systems. Within a whisker of the national average at 202,000 cells/ml, SCCs vary from 110,000 to 320,000.
“The overwhelming majority of producers (96%) see high standards of cluster hygiene as an essential part of modern mastitis control,” reports Dairy Group senior dairy husbandry consultant, Brian Pocknee who co-ordinated the study. “And fully 80% are now routinely disinfecting clusters at milking in some way.
“There’s a good understanding of how important the practice can be in controlling contagious mastitis. However, the value of routine cluster disinfection in environmental mastitis control is noticeably less well appreciated.
“We clearly need far wider industry recognition of the extent to which Streptococcus uberis, can be spread from cow to cow. Just because its primary reservoir is the environment doesn’t necessarily mean cluster hygiene isn’t important in keeping it at bay.
“Our study also underlines the need for a much greater appreciation of the mastitis-spreading risk of cows with high Somatic Cell Counts,” Brian Pocknee stresses.
“Around three quarters of herds always disinfect their main clusters and dump units after milking cows with clinic mastitis. But just 45% of herds always disinfect clusters after milking cows with high SCCs and around 30% never do. Yet we know that high SCC cows can have more bacteria in their milk than those showing clinical mastitis. This is another reality more milk producers need to both recognise and act upon.”
The Sorgene study shows cluster dipping remains the most widely used disinfection system, with almost half of herds employing it, compared to just over two in 10 using automatic back-flushing and one in 10 cluster spraying. It further highlights a substantial increase in the popularity of routine cluster disinfection in recent years. While this is evident across all three main systems, automatic back-flushing has clearly led the way. What is more, no less than a third of those not employing an automatic system are considering installing one.
No less than half of those with back-flush systems have installed them in the past 12 months and 90% within the last five years. However, the vast majority previously employed another form of routine cluster disinfection, with many having done so for 10 years or more.
“There’s clearly a wealth of long-standing cluster disinfection experience to draw on,” observes Brian Pocknee. “The vast majority of producers (82%) see reduced mastitis cross-infection as the most important benefit of the practice with a similar proportion (85%) regarding a good disinfectant as vital to success.
“While 70% are using peracetic acid/hydrogen peroxide disinfectants, though, around 20% continue to use chemicals like sodium hypochlorite that require relatively long contact times to be effective. And a significant minority are only using water.
“Here again, better understanding would really improve cluster hygiene in practice; in particular, appreciating the need to follow well-researched manufacturers’ recommendations for the disinfectant used.
“By far the most widely used product in our study – Sorgene 5 – for instance, should be used at a concentration of 1:400. And rinsing the cluster is recommended to remove any dirt ahead of complete immersion for a few seconds. Yet too often in my experience rinsing is neglected and dilution rates are far too approximate.
“Time, as ever, appears to be the real stumbling block” Brian Pocknee notes. “Indeed, two thirds of producers identify time requirements as the biggest drawback of routine cluster disinfection.
“In practice, though, around two thirds find the technique extends their milking time by less than five minutes and nearly 40% – including many without the luxury of automatic back-flushing – see no additional time implications whatsoever (Figure 3).”This suggests the time problem may be more perception than reality in many cases. It also indicates, perhaps, that many herds could afford to be a little more rigorous in their cluster disinfection routine.”
The fact that nearly a third of producers involved in the national study feel even the most time-consuming technique of cluster dipping has a wider practicality than just following the milking of mastitic or high SCC cows clearly suggests many consider the benefits significantly outweigh any drawbacks.
As does the sheer number who continue to routinely disinfect clusters by dipping in preference to the faster but generally less effectively applied manual alternative of spraying.
Brian Pocknee accepts that disinfecting every cluster after milking each cow is impractical for most herds today in the absence of an automatic system.
Despite the paucity of scientific evidence from controlled trials under modern conditions, he believes routine disinfection of clusters after milking both mastitic and high SCC cows could have an important part to play in better mastitis management. He does, however, question the economic justification for many automatic back-flushing systems in the absence of grant support and where the cause of mastitis problems is not fully established.
“Many dairymen clearly recognise the importance of good cluster hygiene these days,” he concludes. “The key challenge is to ensure the best practice that will really minimise bacterial cross-infection via the teat cup liners.”
