Worm larvae are a common issue in the cooler weather for grazing animals and can often be hard to detect.
Once the larvae eggs are passed through the faeces and conditions are suitable for development, the eggs hatch to larvae and undergo two stages of growth before de- veloping into the third stage becoming infective.
If the conditions are suitable the larvae can develop in a very short period of time. A donor sheep infected with H. contortus cultured and incubated for 7 days at 25-27 degrees produced approximately 800,000 infective larvae that could potentially infect other sheep.
Larvae are very resilient and can survive in low temperatures, even a frost. The larvae become a major issue as it can remain in the pastures for up to 3-7 months.
Warmer and humid conditions are when the larvae are most active due to a greater demand for limited food reserves, where as in cooler temperatures the larvae is less active, consume fewer reserves and will survive longer.
Unfortunately larvae can’t be seen with the naked eye on pastures hence the importance to understand the conditions at which worm eggs develop.
Highly contaminated pastures are particularly unsuitable for young sheep which are at most risk of infection. Pasture contamination can also be managed with rotational crops and worm tests conducted on farm.
Sourced from AgriWest Rural