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SubscribeA good biosecurity plan must assume that introduced sheep are infested with lice regardless of their history or whether there are no lice or signs of lice. Your decision on how to manage the introduced sheep will be a personal risk management choice. This is based on
There are four management options to keep your flock lice-free in the long term. You can use the LiceBoss Treatment Guide to help choose an option to suit your situation.
The options are presented below in descending order of biosecurity rigour. Additional notes for the options are further below.
Option 1: Treat orally; or shear and treat topically immediately*
Note: This option may produce high chemical residues in the shorn wool if the sheep had already been treated off-shears or in short wool.
This option is rarely cost-effective. See below for situations it may suit and how to assess the cost.
Option 2: Treat short wool sheep immediately
Note: this option may produce high chemical residues in the shorn wool if the sheep had already been treated off-shears or in short wool.
Use another option for sheep with longer than 6 weeks wool.
Option 3: Quarantine and decide treatment at the next shearing†
Option 4: No quarantine and decide treatment at the next shearing†
All options assume that you apply any oral or off-shears/short wool topical treatments according to label instructions (including within the correct time since shearing, where applicable) to all sheep in the mob or flock and maintain the necessary period of isolation after treatment as directed by the product label.
*Option 1, despite being the best option for biosecurity, may not be cost effective especially if shearing is required. It best suits these situations:
To weigh up Option 1 for your situation:
When estimating the cost of fleece damage using the Long Wool Tool you will need to make assumptions about the level of rubbing and when it might appear, both in the introduced sheep (if no rubbing is currently evident) and in your existing flock (which could vary considerably). The extent of rubbing that will appear in your flock, if lice spread to them, will depend on how lousy the introduced sheep are, how many and which of the introduced sheep are exposed to your existing sheep (as they will have different levels of infestation) and when the contact takes place before the existing sheep are shorn. You might consider a number of scenarios, such as a worst-case scenario where the level of rubbing is high well in advance of shearing, and also a moderate and a light level of rubbing in your main flock, and estimate how likely these scenarios are. Weigh these up against the costs associated with an early shearing and treatment.
†In options 3 and 4, also check for lice each 2 months leading to shearing. If lice become apparent before the next shearing, the introduced sheep and any they they have mixed with may require an interim long wool treatment to suppress lice. Consult the Long Wool Tool to see if this is warranted. As long wool treatments cannot eradicate lice, an off-shears/short wool treatment will also be required at next shearing. Different long wool treatments are registered for different lengths of wool and for different times until shearing. Consult the Products Tool or product label to choose a suitable product.
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