The reduced pasture heights for much of Victoria are increasing the susceptibility of sheep (and cattle) to internal parasites.
Grazing below a pasture height of 4cm will increase the ingestion of infective larvae. While most egg contamination occurs in the summer-autumn period, up to 40 per cent can come from eggs deposited during late spring and early summer.
Typically, in spring there is an abundance of quality pasture which allows your sheep to cope with the worms they have.
However, given the challenging season this may not be the case. Farmers who are early weaning due to low feed availability need to prioritise worm control as weaners are the most susceptible livestock class to internal parasites.
Livestock that are in poorer condition and potentially on restricted nutrition can have a reduced resistance and resilience to internal parasites.
It’s crucial to assess worm burdens during high-risk conditions, which in the current seasonal conditions could include lighter stock grazing shorter and highly contaminated pastures.
It’s also important to have worm-free paddocks set up for weaners. Ideally, paddocks that weaners are put into will have only been grazed by sheep who received an effective summer drench.
The best paddocks to put weaners into may be ones that have been hay paddocks, are new pastures or paddocks that have been grazed by mature cattle.
Sheep that are infected with worms may show signs of scours, weight loss or event death. It is essential to monitor worm burdens using Wormtest 4-6 weeks after the weaning and treat based on results.
Summer drenching is the key to minimising this worm carryover into next year – by making sure there are few worms in your sheep getting a free ride to autumn.
Management of internal parasites is essential for animal production and welfare, especially during high-risk times when stock are in light condition.
Seek advice from your animal health professional such as a veterinarian or consultant to assist with developing a worm management strategy.
For more information about managing in dry seasonal conditions visit agriculture.vic.gov.au or call 136 186.
