Red Lice (Bovicola ovis, Bovocola limbata) is the most important lice species in sheep and goats. It has a major economic impact on wool, hair and meat production.
Lice spend their entire life cycle on sheep / goats and move constantly through the fleece. This free movement facilitates the transfer of lice from infected to non-infected animals. To complete their life cycle (from egg to an adult louse that lay eggs again) takes ± 29 days. A light lice infestation (± 5000 red lice) can become major problem within 2-3 months due to the short life cycle.
Autumn and winter months are the most favourable times for red lice to multiply, the reason being is that:
The effect on wool production, clean yield and price (Joshua, 2001 NSW)
A light lice infestation cause:
The total R-value loss per sheep with light lice infection is ± R19.50 (The value is calculated at R75 / kg wool, average 5kg of wool per sheep)
The largest source of reinfection in sheep and goats are the remaining lice that were not effectively controlled by previous treatments.
Pour-on’s are ready-to-use products that are applied with an applicator on the back in a broad band from between the ears to the tail. Regardless of the label claims, the best use for pour-on remedies is within 24 hours from shearing. This will distribute a higher concentration of the active ingredient all over the body in the lanolin layer and ensure the best control.
The advantage of pour-on remedies is that
Dip remedies can be applied through plunge dipping, a spray race or 'jetting'. Sheep can only be dipped 3-4 weeks after shearing and up to ± 2 months before shearing.
Key factors for success with dipping is