NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
Recent weeks have seen incidences of disease (such as pneumonia) in concurrence with energy and protein deficiency in livestock (both sheep and cattle), particularly in the weaner age group. Although no WormTests have been done on these animals, it is logical that their parasite burdens might be heavier due to these deficiencies. Moral of the story is make sure your ration is correct and supplying enough energy and protein—measure by weight how much grain and hay you are feeding and use the Drought Feeding Calculator to work out if the energy and protein is sufficient for the class of livestock.
I am continuing to see drought affected adult cattle with larval ostertagia burdens in their abomasums, which are contributing to their welfare state. I am also warning producers that the efficacy of many of the pour-on drench products may be reduced as they are lipophilic—meaning that they require fat in order to be absorbed into the animal's system, which will be difficult in cattle that are in poor body condition. Lice and worm control in cattle is indicated at the moment, and product choice should be discussed with an agricultural adviser or veterinarian prior to purchase.
There have been few WormTests submitted for the Forbes area, and based on what we have seen in sheep with a reasonable drench history, egg counts are expected to be low. However, it would be sensible for producers to monitor their individual situation by conducting worm tests across their flock. Pre-lambing and weaning are two crucial time points where drenching should be considered. And for sheep moving on to a property, quarantine drenching should always be undertaken to prevent the introduction of drench resistant worms. See Wormboss for further advice on quarantine drenching.
[Editor’s note: This is particularly important during drought. Drought conditions decimate larvae on the ground leaving few or none in refugia. When conditions improve the resistant worms carried in the stock will be the only ones to re-contaminate pastures. This can dramatically escalate the resistance status on a property in one season.]
There has been below average rainfall so far this winter, and as a result feed has been shorter than expected for this time of year. Some producers have been forced to graze pastures more heavily, rely on supplementary feeding and wean lambs earlier than they otherwise would.
While the cold weather will stop most eggs from hatching and reduce the activity of larvae, this will not decrease numbers of existing worm larvae or their viability. Overgrazing pastures will increase production risks as most larvae lie close to the soil, and early weaning will put lambs at risk. Early weaned lambs do not have a well-developed immune system and struggle to cope with heavy worm infestations. Producers would benefit from a weaning drench to boost production, however the potential for resistance development needs to be considered.
Also, we must keep in mind that lambs may also present with scouring due to other factors such as inappropriate age of weaning, nutritional scours (sudden change in diet, fast introduction to lush pastures, nitrate toxicity), bacterial infections, or coccidiosis. Worm egg counts are necessary to rule worms in or out as the cause of scours.
[Editor’s note: despite these issues that may come with early weaning, do NOT let them delay weaning. Early weaning is an essential strategy during drought, for both the good of the mother and the progeny.]
In the East, the few WormTest results that have come through over the past month have shown low-moderate egg counts. A worm egg count of 440 strongyle eggs per gram (epg) was shown in a pregnant five-year-old ewe that had died. Larval culture indicated 2% Haemonchus (barber's pole worm), 47% Trichostrongylus (black scour worm), and 51% Teladorsagia (brown stomach worm). The mob of 500 mixed-age lambing ewes was being grazed on dry native grasses and fed pellet mix, and had been drenched with an abamectin and closantel drench before lambing.
A mob of pregnant ewes in good condition without evidence of worm burden recorded low numbers of strongyles (100 epg) – 69% Haemonchus, 11% Trichostrongylus and 20% Teladorsagia.
And worm egg counts from 4 lambs that had developed scours and died recorded an average of 16 strongyle epg, and 40 Nematodirus (thin necked intestinal worm) epg. Inflammation of the small intestine was noted on post mortem and, despite only low numbers of coccidia, it is likely that coccidiosis contributed to the scouring and deaths in these lambs.
In the Western part of the region only two WormTests were submitted. In the Deniliquin area a group of lactating, old merino ewes that were in poor condition were tested and found to have an average strongyle count of 424 epg. This consisted of 50% black scour worm and 50% brown stomach worm. The group had last been drenched in June last year with a triple combination drench containing a ‘mectin’, a ‘clear’ and a ‘white’ drench, specifically abamectin, levamisole, and oxfendazole.
The other submission was from rams from further west in the region that had an average strongyle count of 76 epg. There was no evidence of coccidia, liver fluke, stomach fluke or nematodirus eggs in the sample. They had previously been treated with the same triple combination as listed previously.
With most pastures in many regions of the South East being short and green and most animals under some degree of nutritional stress, monitoring for worms continues to be important. Results from worm counts in the South East have again been variable this month emphasising the importance of worm testing on your own property. Conditions unsuitable for worm eggs to hatch (too dry and cold) will cause many worm eggs to die, but larvae that have opportunistically hatched during suitable conditions in the past months are available for pick up, and larvae survive a long time in cold weather. Grazing pressure into the larval pick up zone (close to the ground) is intense. Sheep are being closely monitored for signs of winter scours and faecal worm egg counts are being conducted.
The variability in egg counts is largely occurring due to the differences in grazing management, the presence or absence of barber’s pole worm on the property, and the drench use history. Barber’s pole worm is an emerging problem in the South East and although conditions are not suitable for it now, it can still show up on worm egg counts and contribute to anaemia. Individual counts and culture have proved important in interpreting the results. For example, it is very important to differentiate whether a count of 400 eggs per gram is due to barber’s pole worm, indicating a potential need for a barber’s pole control strategy in the spring, or an immediate scour worm problem. It is also important to remember that barber’s pole worm will have a different drench sensitivity to your scour worms, and understanding that different worms have different resistance issues is a key player in controlling barber’s pole worm on your property. Even if your property has never had a problem with barber’s pole worm before, you are very likely to have some drench resistance issues, particularly to the white drenches, and to the mectin drenches such as ivermectin and abamectin.
Like many other regions, dry conditions remain, and producers face continued supplementary feeding. Although dry environmental conditions reduce worm egg hatching and larval survival, internal parasites can still cause illness. Recently, marked Haemonchus (barber's pole worm) burdens causing illness and deaths were found in a flock of Merino ewes. In this case, continued grazing of very short pasture may have increased larval uptake, while a reduction in immunity late in pregnancy was also likely to be a factor. Spring lambing flocks should consider a pre-lambing drench.
The drought has worsened and a lot of stock remaining in the region are being fully or supplementary fed in confined sacrifice areas for any length of time. There are increased concerns about sourcing fodder for the stock remaining in the region. Very few WormTests have been performed in sheep. Those that have been performed show low worm egg counts. There has also only been a single WormTest conducted in cattle which also showed low worm egg counts. WormTests are still being encouraged for producers despite the ongoing dry conditions due to the increased risk of larval ingestion related to supplementary feeding from the ground for long periods.