by Jenny Cotter, Department of Agriculture and Food Western Australia
This note deals with sheep breeds that shed their fleeces and/or have fleeces that are wholly or partly kemp or hair (Table 1). Some of these sheep have coloured fleeces.
Click here to find commercial products for treatment of lice.
Claims have been made that external parasites do not establish on shedding or hair sheep breeds and anecdotal evidence does suggest that lice are rarely detected on these breeds and their crosses.
The fleeces and skins of some of these breeds are quite different from those of a Merino, so they may be poor hosts for external parasites. However, external parasites will survive on some individuals.
Table 1. Fleece and shedding characteristics of some sheep breeds
Breed |
Fleece type and colour |
Fleece shed annually? |
Afrikaner |
Hairy, kemp free; white (in Australia) |
Yes |
Awassi |
Double coated, containing hair, heterotype, wool and kemp fibres; often coloured |
No |
Damara |
Outer kempy coat, inner layer of wool; range of colours |
Yes |
Dorper |
Wool and kemp; black head with white body, or all white (White Dorper) |
Yes |
Karakul |
Double coated; black at birth, greyer with age |
No |
Namaqua |
Hair; coloured |
Yes |
Van Rooy (White Persian) |
Hair; all white |
Yes |
Wiltipoll |
Double coated; white |
Yes |
Wiltshire Horn |
Double coated; white |
Yes |
Note: The Dohne Merino, the South African Meat Merino (SAMM) and the Afrino are not included as they are wool-growing sheep.
The direct cost of lice infestation of sheep may be small if their fleeces have little or no market value, but effective lice treatments will be required for the following reasons:
Off-shears lice treatment of shedding and hair breeds is the recommended option if they have, or are suspected to have lice. Although the sheep may not require shearing, and their fleeces may have little or no value, treatment off-shears will give the best chance of lice eradication. Shearing itself will markedly reduce lice numbers. Off-shears treatments should be applied according to label directions. That is, backline treatments should be applied within 24 hours or 7 days (depending on the product used), and dips within 6 weeks after shearing, but preferably within 2–3 weeks.
There are numerous products registered for lice treatment of sheep off-shears, and many factors to take into account when deciding which product to use. As well as cost per dose, also consider the possibility of lice resistance to the chemical, operator risk, meat (and possibly fleece and milk) withholding periods, ease of application, stress to sheep and the operator during treatment, and the risk of other problems or diseases associated with particular treatment methods.
Long wool lice treatment of shedding and hair breeds is not recommended. It is better to wait and treat off-shears. If sheep are treated in long wool and not subsequently shorn and re-treated, the best that can be hoped for is that lice numbers will be suppressed to a low, tolerable level. None of the chemicals registered for use on sheep with long wool (more than 6 weeks since shearing) will eradicate lice. If eradication is your ultimate goal, a second treatment will still be needed off-shears. It also carries the risk of selecting lice for chemical resistance, leaving chemical residues in meat or fleece and exposing workers to the hazards of chemical use.