DAIRY NEWS FEBRUARY 27, 2018
22 // ANIMAL HEALTH
Teat sealant use rising for noninfected cows PAM TIPA pamelat@ruralnews.co.nz
THE USE of internal teat sealants
(ITS) at drying off has been increasing annually, say Kristen Baxter and Greg Chambers of Zoetis NZ Ltd. Although its effectiveness was known in the 1990s, its use has grown faster since work was published on teatsealing heifers in 2008 and also due to the general move away from antibiotic dry cow therapy. The development of heifer teatsealing trailers in Canterbury in 2009, and technician teams, have led to many veterinary practices administering ITS to at least 60% of heifers, Baxter and Chambers said in a paper to the New Zealand Veterinary Association (NZVA) Conference last year. They were speaking to the Large Animal Veterinary Technicians Group (LAVT), a special interest branch of the NZVA formed under the Society of Dairy Cattle Veterinarians. It is often the veterinary technicians who administer dry cow treatments. In cows, ITS can be more effective at preventing mastitis than antibiotic
dry cow therapy (ABDCT), due to long duration of action and no limitations from an antibiotic’s spectrum of activity, the paper said. Many studies have compared outcomes in cows that received ITS alone at drying off with cows that received ABDCT or no treatment. They have found that although antibiotics are the best way to cure existing intramammary infections, they are less effective than ITS in preventing new infections. “In the last few years, with increasing concern about antibiotic resistance and a continually decreasing average herd bulk tank somatic cell count, more and more farms are also choosing to treat cows that are uninfected at drying off with an ITS alone,” the authors say. Although this has appeared to be a recent change in the industry, the DairyNZ SmartSAMM (Seasonal Approach to Minimising Mastitis) has been advocating ITS alone in uninfected cows since the early 2000s. “Increasingly, the default position for a cow at drying off is to treat only with an ITS, and use ABDCT when justified,” the paper says. “This practice has extended the timeframe in
which intramammary treatments can be applied, so that in many [veterinary] practices ITS/ dry cow therapy insertion now stretches from early April to mid July.” How dry cow therapy is chosen All dry cow therapies, including ITS, are restricted veterinary medicines and so must be prescribed by the farmer’s veterinarian after a consultation. Every farm is unique and the approach depends on many factors that can require a lot of information. Data management systems like Infovet may be used. Veterinarians typically make herd level assessments before making dry cow therapy decisions for individual cows. “Without performing milk cultures on every quarter of every cow, we do not truly know which cows are infected and so require ABDCT. “In practice, cows with a higher risk of being infected at drying off are identified from the current milking season’s data – herd test somatic cells counts and clinical mastitis history. “The definition of an infected cow varies around the world, especially the individual somatic cell count (ISCC) above which cows are deemed infected.”
APPROPRIATE INSERTION CRITICAL APPROPRIATE INSERTION OF all intramammary products is critical for not only avoiding adverse events (e.g. mastitis caused by a hygiene breakdown) but also maximising their efficacy, and therefore the farmer’s return on investment. Among best practice advice, the paper says veterinarians and technicians must ensure farmers
remove internal teat sealant at calving by manually stripping each quarter 10-12 times before the first milking, to prevent entry of sealant particles into the vat. “Remind farmers that internal teat sealants have an eight milking withholding period, which is also defined as the colostrum period.” Full and appropriate advice
on best practice administration can be accessed by contacting a Zoetis area manager or visiting www.dairywellness.co.nz. This advice is continually updated from years of experience in New Zealand and overseas. In addition, the Society for Dairy Cattle Veterinarians has recently created several dry cow therapy resources.
Cow wearing a urine sensor.
SENSORS JOINING THE MOB TO GUARD WATERWAYS AGRESEARCH SAYS it has devel-
oped world-leading sensors to better understand how nitrogen is being excreted by cows, and so how best to tackle its effects on the environment. The urine sensors, a work in progress since 2010, are attached to grazing dairy cows to get detailed measurements every time the cow urinates, including volume and frequency, and crucially the concentration of nitrogen in the urine that may leach into soil and waterways, perhaps causing algal bloom. The urine sensors give much greater understanding of the behaviour of the cows, which can help develop techniques to mitigate nitrogen leaching from farms, says AgResearch senior scientist Dr Brendon Welten. “Other sensors exist around the world to provide data from livestock, but these sensors we’ve developed are unique in their ability to record nitrogen concentrations each time the cow urinates during grazing,” Welten says. “We can learn, for example, how different species of pasture affect the amount of nitrogen excreted in urine.” The sensors weigh about 1.5kg and attach to the cow by a harness connected to a lightweight cow cover. Several instruments record the data (temperature, pressure and refractive index), storing it in a data logger
remotely accessed via a wireless network system. The sensors have already been used in the UK and Australia. “The operation of the sensors is complex, and at this stage we are working towards offering the sensors to other researchers around the world to allow them to use the technology to make similar gains,” Welten says. “AgResearch will have the expertise to support those researchers to use the technology and maximise the benefits from it.” The sensors have contributed to important progress made in the Forages for Reduced Nitrate Leaching (FRNL) programme involving DairyNZ, AgResearch, Plant & Food Research, Lincoln University, the Foundation for Arable Research and Manaaki Whenua (Landcare Research). DairyNZ senior scientist Ina Pinxterhuis says the results confirm the variability in urinary nitrogen excretion over the day, necessitating many repeated measures. “The sensors make this possible.” “It is also great to see that the options we examine to reduce nitrate leaching result in lower daily urinary nitrogen excretion and lower nitrogen concentration, if not during the whole 24 hours of the day, at least for some parts. This information provides new options for management too.”
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