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Questions

1. Why can the larvae of the thin-necked intestinal worm survive very dry conditions on pasture?

2. What does ASBV stand for and why is it useful for flystrike management?

3. Is it usual for sheep lice to breed on animals other than sheep?

4. What is the most common form of liver fluke disease (fasciolosis) seen in goats in Australia?


These lambs are scored for breech wrinkle at marking, which generates an Early Breech Wrinkle ASBV
These lambs are scored for breech wrinkle at marking, which generates an Early Breech Wrinkle ASBV

Answers

1. Why can the larvae of the thin-necked intestinal worm survive very dry conditions on pasture?

Nematodirus (the thin-necked intestinal worm) infective larvae are doubly protected from dry weather as they develop within the eggshell not out on the pasture as do larvae of other gastrointestinal roundworms of sheep and goats. The combination of eggshell and the larval sheath make these larvae better able to survive desiccation.

2. What does ASBV stand for and why is it useful for flystrike management?

Australian Sheep Breeding Value: this index or value is useful because it allows producers to confidently select sires on the basis of their genes rather than environmental effects.

Sires can be selected for improved performance on values that reduce the establishment of blowfly infestations such as Early Breech Wrinkle (EBWR), which will assist in the selection of rams that will breed progeny with less wrinkle; Dag (Dag), to assist in the selection of sheep less prone to dag/scouring; Breech cover (BCOV), to assist in selecting sheep with less wool on the breech.

3. Is it usual for sheep lice to breed on animals other than sheep?

No. Sheep lice do not breed on animals other than sheep—with the possible exception of goats, but only in very rare instances.

Birds do not carry sheep lice and they do not remain in wool rubbed onto fences, trees or other structures, so these are not sources of infestation.

Nearly all new infestations begin from contact with infested sheep.

4. What is the most common form of liver fluke disease (fasciolosis) seen in goats in Australia?

Chronic fasciolosis is the most common form of liver fluke disease seen in goats in Australia.

Clinical signs of fluke infestation are always dependent on the number of ingested metacercariae. In the chronic form of the disease the infectious dose is about 200-800 ingested metacercariae. Signs of disease such as bottle jaw, emaciation and weight loss develop gradually as the infection progresses.

Less commonly, a heavy intake of metacercariae results in an acute type of infection in which goats die suddenly, and often without any clinical symptoms. When moderate numbers of metacercariae are ingested a subacute form of the disease develops in which goats slowly become lethargic, anaemic and may die. Weight loss is characteristic of this form of the disease.