The Sunday News
Mhlupheki Dube
THIS week we want to talk about small ectoparasites in cattle. These are parasites which are found on the external body of your animal. Common ectoparasites are ticks which most farmers are aware of and often encounter in their herds. The less common one but of equal economic importance are lice which will form our subject of discussion this week.
However, before I expand on lice I wish to just make a comment regarding the welfare of our smallholder communal herds against the background of excruciating heat wave. This heat wave is really taking its effect on the communal herd and mortalities are being recorded and the strain on farmers is almost unbearable. It is now common to see animals stampeding with humans in scarce boreholes for water. While this article has no immediate solution to the scotching heat it just wishes to amplify communal farmers’ call for more dams and water reservoirs so that such phenomena as the heat wave can have a mitigated effect next time if it does recur.
Now back to our lice! Lice are small, flat-bodied insects with legs modified for grasping hairs. Lice irritate cattle causing them to bite, scratch and rub. There are generally two broad categories of lice based on their method of feeding and these are biting and sucking lice. Both biting and sucking lice are spread by direct contact and are typically found along the animal’s topline, particularly around the withers.
– Biting lice (Bovicola bovis) survive by feeding on the skin, hair and sloughed skin cells of the animal. A complete life cycle of this louse can occur in as little as three weeks, and adults can live as long as 10 weeks. Biting lice have larger rounder heads.
They feed on skin debris, blood and scabs. Despite being apparently less invasive than sucking lice, it is biting lice that produce the most severe irritation. Biting lice are mostly found on the neck, shoulders, back and rump of an animal.
– Sucking lice survive by penetrating the skin and feeding on blood. These have relatively small narrow heads designed for piercing the skin and sucking blood. In large numbers they can cause anaemia. They are usually found around the head and neck of cattle. The species of sucking lice include: the longnosed cattle louse (Linognathus vitulii), the little blue cattle louse (Solenopotes capullati) and the short nosed cattle louse (Haematopinus eurysternus).
The eggs, of both types are glued singly to hairs and hatch in about two weeks. The nymphs, or immature stages resemble adults but are smaller.
Lice, because of their small size, can at times escape the human eyes but obvious symptoms of lice infestation in your cattle include constant rubbing by affected animals. An animal which is observed frequently rubbing against trees and poles of the kraal should be inspected for lice infestation. The biting and sucking irritates the animal and gives it a desire to scratch. The infested animal will rub mostly the area around the neck and the rump where infestation tends to be heavy. Continued rubbing causes injuries to the skin and at times blood can be seen around the scratched area. This also results in hair losses especially around the neck, shoulders and rump. As a result the coats of lice infested cattle take on a rough scruffy appearance with some areas of skin rubbed raw. Lice can be an important cause of economic loss when cattle are in poor condition and are constantly irritated. Diseased or nutritionally stressed animals will develop more severe lice infestations than healthy animals.
Insecticides can be used to treat infected cattle. However, they may not be as effective on louse eggs. This means that after treatment, eggs can still hatch and continue the infestation. With some insecticides, a follow-up treatment two to three weeks later is necessary. This time interval is critical to achieve control, as it allows time for the eggs to hatch but not to mature into adults which will lay eggs themselves.
