March Seasonal Focus

Summer worms

End of summer does not necessarily mean the end of worm woes in flocks and herds. In areas where both barbers pole worm and scour worm are an issue, now is the time to be ensuring a larval culture is undertaken so you can be sure that the worms that are being targeted are in fact present. Oftentimes producers can fall into the trap of using some ‘rules of thumb’ or ‘word of mouth’ when it comes to decision making for which drench to use with the aim of targeting worm species.

For an overview of summer worm control in cattle, goats and sheep see the ParaBoss webinar.

A recent report from Victoria shows the dangers. Five mobs of sheep were purchased in February from northern NSW. On arrival they were tested and found to have worm egg counts averaging about 5,000 eggs per gram (epg). They were treated with a drench that did not contain either of the ‘new’ active ingredients (derquantel and monepantel). Two weeks later sheep were still poor, some died and worm egg counts had actually gone up, with one mob recording 18,000 epg. A veterinary post-mortem examination confirmed death was due to barber’s pole worms.

Not doing a ‘quarantine drench’ can be fraught with danger, as what we do know is that the worm situation on an individual farm is very much specific to that property and herd/flock.

So a drench that usually works on your property is likely to not work against worms that came from somewhere else!

A quarantine drench must contain one of the new active ingredients (derquantel and monepantel), along with three other broad-spectrum chemicals. More specific strategies may be needed when purchasing sheep, cattle or goats from areas with high resistance (including NNSW) or where liver fluke are common (most of the higher rainfall and irrigation areas of south-eastern Australia).

Therefore, what’s going on elsewhere may not be very different from what’s happening on your own operation. The key here is Test – don’t guess! Information is key to staging a campaign on the worms in your herd/flock, and the power of knowledge is very much integral to effective management of internal parasites and preventing the onset of resistance.

The only way to know exactly which worms you are dealing with is to test and request a larval differentiation. A larval differentiation is where the parasitology laboratory incubates the worm eggs and then identifies them under microscope to give a firm diagnosis of which worms are present. Most of our problematic worms have eggs that look the same under a microscope, which makes product selection for control less accurate without a differentiation. 

Goat producers will benefit from ongoing monitoring of worms in herds. An integrated approach is important where product choice is limited.

Sheep blowflies

The fly situation in sheep and cattle continues to challenge many – now is the time to stay vigilant with checking sheep. Depending on when preventative chemical was applied, be on the watch for the product approaching the end of its protective period.

Tick control

Cattle producers should also be on the front foot with ticks and cleaning up any residual tick populations on their animals. Theileriosis has been reported in many areas including southern Western Australia and Tasmania and avoiding losses from this deadly disease requires effective control of bush ticks. Summer and autumn are peak times for risk of Theileria infection. For more detailed information on Theileria and how to minimise its impact in your herd, click on this link.

Cleaning up pastures

Warm dry weather is a great time to use the conditions to your advantage when it comes to cleaning up pastures for lambing ewes and other vulnerable classes of stock. The wet spring conditions may have seen heavier pasture contamination than usual, and using stubbles along with spelling times that facilitate reduction of worm larvae on pasture will be highly beneficial for the coming cooler, wetter conditions.