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Beyond the Bale : June 2017
Asimple assessment tool is now available to enable producers to calculate the cost-benefit of different footrot management strategies specific to their own circumstances. The tool was built by Macquarie Franklin under the direction of the Tasmanian Department of Primary Industry, Parks, Water and Environment (DPIPWE), with funding from AWI. “In general terms the cost of virulent footrot for an individual farmer is a combination of the productivity impacts and the cost of treatment. Productivity impacts are a combination of loss of stock trading income and reduced wool income – themselves associated with lower body weight, lower lambing percentages and increased mortality,” said program manager Bruce Jackson of the Biosecurity Operations branch of DPIPWE. “Eradication strategies, either conventional or using vaccines, have a high initial cost but (if successful) lower ongoing costs than simply containing the disease. Containment has lower up-front costs but ongoing productivity and annual treatment costs. “Vaccine eradication tends to be the lowest cost option, less than for conventional eradication. Conventional eradication is often unsuccessful and the property reverts to containment; in this case it becomes the highest cost option.” The Excel-based tool available at www.wool. com/footrot has been developed to assist farmers in arriving at a considered decision in relation to footrot control and eradication options for their own situation. There are four steps involved in using the simple tool: Step 1: Describe what your footrot-free enterprise would look like. If there was no footrot on your farm what would the sheep gross margin be? This is the base case against which footrot impacts and cost of control is measured. Step 2: Assess the impact of footrot - before control/eradication measures The overall impact is a combination of the per head impacts on infected sheep and the proportion of the flock affected. Step 3: Assess the costs and effectiveness for the three control/eradication options 1. Containment A combination of treatments to minimise lameness, but with culling limited to chronically affected sheep. The disease is curtailed but not eradicated. 2. Conventional eradication A combination of treatments to initially reduce incidence, followed by an inspection and culling regime to identify and remove all animals that fail to NEW TOOL TO ASSESS COST OF FOOTROT STRATEGIES A new Farmer Footrot Tool will help enable producers with footrot-affected sheep to understand the financial cost of the disease on their farm and to evaluate the cost effectiveness of different strategies to control or eradicate the disease. Footrot management strategies can include footbathing. PHOTO: James Tyson respond to treatment. This strategy is not always successful. 3. Vaccination eradication Administration of a specific vaccine along with the conventional eradication program to speed up and improve the overall result. Step 4: Review overall costs The tool calculates the gross margin under each control/eradication option over 10 years. The containment option has a better gross margin earlier on, because treatment costs and culling etc are lower, but has a lower ongoing gross margin because of some continuing impact of the disease and ongoing treatment costs. MORE INFORMATION www.wool.com/footrot After years of research and development by the University of Sydney School of Veterinary Science, a serogroup specific footrot vaccine is being manufactured by Tréidlia Biovet Pty Ltd and is now available to Australian sheep producers. “The vaccine can only be used after testing has been conducted to determine which virulent serogroups of footrot are present in the flock,” said Professor Richard Whittington from the University of Sydney. “This involves taking swabs from feet with footrot and culturing them in the laboratory and then applying tests to determine which of the 10 (A to I or M) serogroups are present, and how virulent that isolate is. The correct serogroups can then be incorporated into the vaccine.” Senior Research Fellow Om Dhungyel, who conducted most of the field research, emphasised that only one or two serogroups could be incorporated into the vaccine at a time. “Very good cure rates and at least six months’ protection result if no more than two serogroups are injected at one time,” Om said. “Additional ‘rounds’ (a priming and booster shot four weeks apart) of vaccination can start three months after the first round if more than two serogroups are present in the flock. It is still crucial to follow up vaccination with several rounds of thorough foot inspection and culling of any remaining infected sheep.” Mark White, Director of Tréidlia Biovet Pty Ltd, said vaccine was available now for all but the rare M serogroup. A couple of weeks’ notice between ordering and supply is required to do the final customisation for each farm. “Your veterinary practitioner must authorise the supply of the vaccine as well, so it is best to involve your vet right from the start at the sampling stage. Approval of the Chief Veterinary Officer is also required in WA, SA and NSW where virulent footrot is a notifiable disease, so discuss this option with your Departmental Veterinary Officer if you are in one of these three states and would like to use vaccine”. Sheep Veterinary Consultant Dr Paul Nilon from Nilon Farm Health said: “We have used the serogroup specific vaccines on a number of flocks in Tasmania now, and usually achieve a good result if we have identified all the virulent serogroups present and the flock manager is meticulous with the post vaccination inspections.” AWI funded some of the early work evaluating the serogroup-specific footrot vaccine and the University of Sydney and Tasmanian DPIPWE supported on-going studies leading to commercialisation of the vaccine. NEW VACCINE AVAILABLE ON FARM 39