The effectiveness of worm control programs should be monitored to ensure that worm burdens do not reach significant levels. Changes in seasonal conditions, or to cattle management, can allow larger numbers than expected to build up, even when animals have been drenched as part of an annual program. Moderate worm burdens may cause some production loss without any obvious signs of worms being present (‘sub-clinical loss’).
In higher rainfall and temperate environments, some on-going loss of production due to worms is common in younger age classes, so monitoring for signs of worms is important, and a planned program may be necessary. Worm egg counts provide a reliable estimate of worm burden in animals under 18 months. Even in environments where worms only occasionally cause significant production losses, worm problems may develop gradually over time, and it is important to be aware of the seasonal conditions where more frequent monitoring of animal performance is wise.
Checking for the presence and effects of harmful worms involves:
Drenching worm affected cattle should result in an immediate improvement and confirms that worms were involved. However, this is not necessarily the sole problem as under-nutrition may predispose cattle to outbreaks of worm disease. In the absence of a clear response to treatment, you should seek further advice, and worm egg counts will almost always be the first step towards a diagnosis.