Where there's muck, there's mastitis

Where there's muck, there's mastitis

mastitis nz farmingThe costs to the dairy sector from mastitis is put at hundreds of millions of dollars, and science is racing to find a magic bullet for the problem.  But for many, the answer is more managerial than medicinal, reports Owen Poland.

In my late uncle's well worn Manual of Dairy Science, co-authors A.H.R. Amess and H.C. Johnson, observed that mastitis is “easily the most widespread disorder”. While several methods of cure have been attempted, they wrote, “none of them have proved satisfactory”. That was in1925.

Fast forward to 2012, and it seems that little has changed. In fact, the problem has been getting worse, judging by the steady rise in the national Bulk Milk Somatic Cell Count (BMSCC) which measures the extent of the problem.

Mastitis can be caused by more than 100 infectious organisms, the main offenders being Streptococcus uberis and the highly contagious Staphylococcus aureus. Despite the industry's best efforts, it remains the world's most common - and costly - disease of dairy herds. Annual losses in New Zealand are estimated at around $280m. In the UK it's something like $600m, and US costs are put at a staggering $2.5 billion, or 11 per cent of total milk production.

Where there's muck, there's mastitis, they say. South Waikato vet Dr Ian Scott says mastitis is a “moving target” and attributes the increased incidence to changed farming habits such as the push for higher production. Greater use of winter feed pads increases the risk of udder contamination; - “we're being forced to run more cows with less people under more pressure.”

PureMilk consultant Steve Cranefield agrees. While the problem is multifactorial, he says “it's a management disease, not a bacteria disease”, and as farms get bigger they sometimes don't have the management structures in place to ensure that all the basics are getting done.

Those basics were initially laid out in the 1960s with the Five Point Plan (FPP) which prescribed hygienic teat management, prompt treatment of clinical mastitis, dry cow therapy (DCT), culling chronically affected cows and correct maintenance of milking machines. That was followed in 1993 by the Seasonal Approach to Managing Mastitis (the SAMM Plan) which focussed attention on six seasonal control periods and aimed to reduce the BMSCC to an industry target of 150,000 cells/ml.

And now there's SmartSAMM, which DairyNZ describes as an ‘all-you-need-to-know’ online resource that it hopes will save more than $100m a year in mastitis costs. But while there may be a big pot of gold waiting for those behind a cure-all treatment, Ian Scott says “the chances of achieving it are very difficult”.

Along with disinfectant-based teat sprays, DCT is still the mainstay of most treatment regimes. Taranaki vet Guy Oakley says that being in a ‘small herd’ province means that there's a high level of farmer compliance which prevents the mastitis problems experienced in large-scale operations. The use of longer-acting penicillin-based antibiotics in DCT also helps because “the longer the antibiotic is in contact with the bacteria, the better the kill rate seems to be”.

More countries are starting to prohibit the use of antibiotics in food-producing animals though, and DairyNZ's chief scientist, Dr J Eric Hillerton, says that trend “seems inevitable” here as well. Dairy farmers, he says will need to review their use of DCT as part of their annual health plan.

It's estimated that up to 20 percent of animals will get new infections during the dry period if they haven't received DCT, so farmers tend to blanket-treat all stock. And while he's conscious that mass medication of animals is now a ‘dirty word’, Guy says farmers need to do a risk/benefit analysis on the basis of whether contagious mastitis could ruin their season if they don't use antibiotics. The fact is, he says, if you use a lot of dry therapy and hardly have any cows calving with mastitis “then you're going to have a fairly sweet run”.

The industry also has to be careful not to throw away tools “that have been central to good outcomes,” says Ian, who adds that part of the vets’ role is to be sceptical about the large range of new “miracle treatments” that are scientifically unproven. “I don't think we need a whole lot of silver bullets, we just need a collective approach to smarter management.”

The growing use of non-antibiotic teat sealants is a case in point. Sterile technique is critically important, and while it won’t cure existing infections, it is useful for first-calving heifers. According to Ian, it's probably been “the biggest step forward available in terms of managing heifer mastitis”.

Culling older infected cows also remains a “key part” of the Five Point Plan says Guy. But with many farmers once again under financial pressure from falling payouts, Ian says some have been tempted to boost cash flows by selling heifers to China and “that means more older cows are kept”.

Another issue is farmer education. Ian says that cell counts can be dramatically reduced if farm managers are focused on finding “offenders” and dealing with them immediately. However relatively inexperienced, and tired, staff on bigger farms are sometimes tempted to “have a look in the morning” to see whether the problem is getting worse. By then it's often too late. Manager observation skills and staff training, he says, are all “significant factors in controlling mastitis”.

To that end, Steve Cranefield - in conjunction with Agriculture ITO - has developed a new Mastitis Management programme. Now in its second year, it teaches farmers how to look at problems on their own farm and then develop specific year-round plans.

“They understand the problem, they understand the relevance to them, and they can make some decisions that will have a direct impact on what they do.”

Given the high cost of pharmaceuticals, it's perhaps little wonder that more farmers are turning to less expensive homeopathics such as Phytolacca, silica, bryonia and hepar sulph, supported by herbal remedies, teat sprays consisting of tea tree and fish oil, and tonics like apple cider vinegar and seaweed extract.

But DairyNZ research has shown that homeopathic treatment is less effective than antibiotics in the treatment of naturally occurring clinical mastitis (44 percent vs 79 percent), and it concluded that homeopathy ‘can not be recommended for mastitis control based on available evidence’. Other studies have produced much higher homeopathic success rates, but Steve says he looks at what's scientifically-based and what's got trial work behind it to prove a result. “If they don't, then I don't generally consider that of use.”

While not yet available in New Zealand, mastitis vaccines are another option and Guy Oakley says a Strep. uberis vaccine “would be a godsend”. European farmers are currently trialling a product called Startvac which prevents the development of a bio-slime layer that protects mastitis-causing bacteria from the action of antibiotics. Startvac's 3-shot programme must be used annually on a whole-herd basis and costs up to NZ$40 per animal - that's around $15,000 for the average Kiwi herd.

Merck Animal Health says that most mastitis vaccines developed so far have been ‘poor’.  It has launched a new project entitled Evasion Molecules in Bovine Mastitis Vaccines (EVAC) which aims to develop a series of vaccines against difficult-to-treat infections caused by Staph. aureus, Strep. uberis and Escheria coli.

With the help of cost calculators, farmers can easily estimate what mastitis costs their business and - therefore - how much they could save if they reduced their somatic cell count. But with counts increasing rather than decreasing, it seems that many don't believe that the potential benefits outweigh the costs.

Which raises the question of whether there should be stronger incentives to do better. Rather than using the current stick approach of penalising farmers with cell counts above the current threshold of 400,000 cells/ml, Ian Scott says it might be more effective to make additional payments to those who get cell counts below 150,000 - rather than just giving them a certificate. As he says, “people are very quick to respond when they are rewarded for a behaviour”. tatua front foots somatic cell counts

Tatua front-foots somatic cell counts

They're a competitive lot at the Tatua Co-operative Dairy Company. In addition to having the nation's highest milk solids payout, they also have bragging rights over the lowest somatic cell count. And the numbers are impressive. Tatua's average BMSCC in the 2011/12 season was 149,000 cells/ml. That's 25 per cent below the national average of 187,000.  

Like the rest of the rest of the dairy industry, Tatua's cell count had been steadily rising - until three years ago. That's when the company went on the front foot. Rather than simply rely on a penalty regime for any SCC above 400,000, the co-op decided to “reward good behaviour” by paying a premium of 7 cents per kg to those suppliers who delivered milk below 100,000. As Supplier Services manager Paul van Boheemen puts it, “if we did nothing we'd lose any marketing advantage we had by saying we had the best quality milk in the country”.

In addition, the company began ranking its 108 suppliers by their cell count. It also published a list of the Top Ten BMSCC Performers in the company's monthly newsletter. It soon became apparent, Paul says, that Top Ten status and the associated peer recognition was probably the “greatest driver” for encouraging farmers to reduce cell counts.

Tatua's Top Ten suppliers all have figures below 75,000 cells/ml, with the best sitting around the 50,000 mark. And since the scheme was introduced three seasons ago, the co-op's average count has fallen from around 190,000 to 149,000, though last year's bumper season helped reduce the tally further because more milk volume usually equates to lower SCC.

So what are the successful suppliers up to? Paul says if cows are kept healthy and stress levels are low then 50,000 is “doable”. He stresses the importance of doing the basics in terms of monitoring cows, using teat sprays and proper treatment. However, he believes that “it's really a function of how well you do them rather than what you do”.

Quantifying the financial benefits is more difficult. The reduced cell count means that Tatua can achieve higher yields from making caseinate. But the real value comes from a marketing perspective. With growing numbers of consumers looking for safe and wholesome products, Tatua can leverage off the fact that its milk (and product range) comes from healthy animals.

It's all about having a competitive advantage rather than actual dollars and cents says Paul, “Most people aren't prepared to pay a lot more because of that, but it's one of those 'soft' factors which provides some advantage.”

 This story originally appeared in Primary magazine. Click here to subscribe.

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