by Garry Levot, New South Wales Department of Primary Industries
In Australia, the national regulatory body that oversees and administers the registration of agricultural and veterinary products is the Australian Pesticides and Veterinary Medicines Authority (APVMA).
For a product to be granted registration the APVMA must be satisfied that when used in accordance with label directions, the product is safe, will not leave illegal residues and will have effectiveness that reflects the claims written on the label. In this regard, there is agreed terminology between the APVMA and product registrants.
To prevent misunderstandings and so that producers do not misinterpret the claims actually made on product labels, here is a glossary of some of the common label terms and their definitions.
BACTERIOSTAT: A chemical added to dip solution, if being held overnight, to inhibit bacterial growth. For example, zinc sulphate (0.5 to 1.0%) or chlorhexidine (0.45%, e.g. Hibitane™). They may be used when dipping young sheep or dipping sheep with skin injuries, e.g. from grass seed punctures or sheep with ‘dermo’ (lumpy wool). Generally, dip young sheep first as they are more prone to diseases. Use bacteriostats only if they are recommended on the dip label, to avoid incompatibility. Some dip products may already contain a bacteriostat.
CHARGING THE DIP: Filling the dip sump and constant replenishment tanks with water and insecticide mixed to the label recommended concentration
CONSTANT REPLENISHMENT: The constant addition of fresh insecticide solution to the dip sump during dipping to maintain a constant volume (and concentration) of dip wash. New dip wash runs into the sump continuously from a supply tank, which contains dip fluid mixed at the appropriate concentration. The fluid from the supply tank replaces the wash taken out by the sheep and automatically compensates for stripping. New fluid must run continuously from the supply tank into the sump while the shower is operating. Adjust the flow from the supply tank, so that after switch-off and draining, the sump level returns to the full mark.
CONTROL: (i) For products applied/ administered to sheep off-shears or in short wool:
Reduction of the lice population to non-detectable levels 20 weeks after treatment in pen and field trials.
CONTROL: (ii) For products applied/ administered to sheep 6 to 43 weeks after shearing:
Reduction of the lice population by >95% after 90 days (or less as supported by data) in sheep examined in pen and field trials. If unequivocal evidence of a reduction in fleece damage caused by the lice at any time period is presented, then the 95% figure may be modified.
DIPPING OUT: A means to minimise the amount of used dip wash that has to be disposed. Dipping out allows the dip volume to drop to 50% full by reinforcing without topping up.
DISINFECTANT: A chemical used to kill bacteria. e.g. to disinfect the dip sump in preparation for dipping or after cleaning out the sump when dipping is finished.
ERADICATION: Elimination of all live lice and viable eggs from treated sheep—the definition is applicable only to products applied off-shears or in short wool and will be determined by inspection of sheep using the standard technique (or any other method approved by the APVMA) 52 weeks after treatment as well as sheep in field trials inspected at 20 weeks.
Currently (2023), no products registered for use against sheep lice carry an eradication claim.
EXPORT SLAUGHTER INTERVAL (ESI): The Export Slaughter Interval is the time that must elapse between treatment and slaughter for product destined for the export market. In many cases, the destination market may not be known at the time animals are sold, so it may be best to comply with the ESI, which is generally longer than the meat WHP. The ESI is not included on the product label. Prior to treatment, check the ESI by referring to the APVMA website, or the Meat and Livestock Australia website or telephone MLA on 1800 023 100 (Australia only).
LONG WOOL: Wool length from 6 weeks after shearing until treatment, as allowed by withholding periods.
OFF-SHEARS: In the first 24 hours after shearing.
REINFORCEMENT: Reinforcement replaces the insecticide removed from the dip wash by stripping. It involves the regular addition of insecticide product, but not water, to the dip.
SHORT WOOL: Wool length from 2 to 6 weeks after shearing.
STRIPPING: The selective uptake of insecticide by wool that results in a drop in dip concentration as sheep are treated.
TOPPING UP (REPLENISHMENT): This is the addition of water and insecticide to the dip to replace the dip wash taken out by sheep. Topping up should occur every time the dip volume drops below 75% full.
WITHHOLDING PERIOD: The withholding period is the time that must elapse between treating the sheep and
- slaughter (Australian domestic market)—Meat WHP
- milk collection for human consumption or processing (Australian domestic market)—Milk WHP
- shearing/fibre collection—may also be referred to as a ‘Wool harvesting interval (WHI)’—Wool WHP.
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