As featured in the Tasmanian Country publication 9th September 2022
Worms, fly, footrot and dermo – Three wet years keep sheep farmers on their toes.
Last week the Bureau of Metrology (BOM) announced what some of us might already have suspected (as we squelch around our farms), a third consecutive year of La Nina weather conditions for Australia. With this in mind, the TFGA had a discussion with Dr Paul Nilon earlier this week regarding, some of the animal health implications resulting from our third La Nina spring/summer.
For those that love a bit of science with their cereal, the BOM describes La Nina as a positive phase of the El Niño Southern Oscillation. It is associated with cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean. Interestingly, and what makes our third La Nina in a row unusual, is the El Nino-Southern Oscillation (ENSO), the natural weather cycle responsible for El Nino and La Nina operates over timescales from one to eight years, hence a third year in a row is not unheard of, but unusual.
There are agricultural animal health implications that arise in La Nina conditions, sheep and in a lesser case cattle may have some health concerns. Dr Paul Nilon is based in Longford and has been a leading agricultural vet in Tasmania for more years than he cares to count.
Sheep lead the charge with increased possible health implications in wetter and cooler summer conditions. If the four horsemen of the sheep La Nina apocalypse were looking for names they would now be: worms, fly, footrot and dermo.
“For all breeds (sheep) worms are going to be the number one issue. We have had two going into our third year of constant larval accumulation on pastures, just because it has been wet and cool. All classes of sheep are going to experience challenges into the summer especially those on irrigated perennial pasture or second year rye grass. The two traditional summer drenches are going to be less effective and there is also a high risk of Barbers’ pole and fluke.
“If it gets warm as well as wet, we can expect a bumper fly season. The Flyboss website (www.flyboss.com.au) is a useful risk management tool. If we are faced with an extended fly season, try to avoid using the same chemical group twice in the one year. This is to try and stave off the resistance to vetrazine and CLik. If using Vetrazine or CLik early in the season switch over to the other chemical group later in the year, such as Ivermectin or Avenge products,” said Dr Paul Nilon.
Nilon suggests the eradication of footrot in sheep, in a wet season may have to be shelved in favour of tight controls. Be prepared for additional foot-bathing or if your flock is vaccinated and responds well to vaccine, an additional vaccine dose maybe a better alternative compared to regular trips to the “baths”. For medium/fine peppin type sheep transmission of dermo occurs between wet sheep, avoid yarding or having young sheep confined when wet.
Weight gain, may not have got a name in my horsemen reference earlier, but Nilon suggests meat sheep although less vulnerable to wet-induced disease compared to merinos need attention. Post weaning may see ewes stack on the weight, predisposing them to metabolic disease in late pregnancy. Be prepared for sacrifice paddocks or confinement feeding to keep the ladies slim.
To listen to the full interview with Dr Paul Nilon, keep an eye on our News for the upload!
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