NSW WormBoss Worm Control Programs
NSW WormBoss Drench Decision Guides
Worm egg count results from the New England region over the last month continue to remain in the low to moderate range in the majority of cases, however some properties have recorded high mean counts (in excess of 1000 epg). Haemonchus are typically the predominant species in culture results, however trichs (black scour worm) have been notable in a few submissions (from both hoggets and adult wethers). Daytime temperatures are now favourable for larval development, however the lack of rain over the majority of the region during September will have prevented this process from taking place. A meaningful rain event (15 mm plus), combined with warm days and absence of frosts will kick-start worm activity. Larval development did in fact take place in the North West Slopes and Plains region following August rainfall. A mob of lactating ewes in the Gurley district had a rise in their mean worm egg count from 300 epg to 1300 epg in the space of a month (mid-Aug to mid-Sept). Sheep producers in the warmer zones will need to be vigilant in respect to worms from now onwards.
Worm monitoring of ewes prior to lamb marking is advised. Ewes which have lambed in low contamination paddocks (after receiving an effective pre-lambing drench) may in fact not require a worm treatment at this time (particularly early lambers). In most instances lambs should not require a drench at lamb marking.
Liver fluke assessment and treatment should be made over the August/September period on those properties known to have a history of the parasite. A major sheep and lamb processor has reported that a high proportion of animals sourced from the New England are in fact infected with liver fluke, indicating that producers are not paying enough attention to the management of this parasite. As I stated 12 months ago in the ParaBoss News, triclabendazole (TZ) resistance (the drug of choice for liver fluke treatment in sheep) is a significant concern in parts of the New England. Repeated sole use of TZ (as with any parasiticide), is indeed very selective for drug resistance. In circumstances where multiple fluke treatments are required over the course of the year in sheep I suggest that producers consider the use of closantel in spring (be mindful that its Haemonchus efficacy may be poor).
Spring often means there are a lot of worm larvae—roundworms and fluke—on pasture, or at least they are there in increasing numbers. A week or so before lamb-marking, consider getting some fresh ewe and lamb poo samples off pasture for a worm egg count (WEC). Ewes and lambs generally don't need a drench at marking, unless it has been a very wet year, lambing paddock preparation wasn't so good, or the pre-lambing drench wasn't effective.
Cattle drenched at weaning in late autumn might need another drench in spring. This varies a lot between farms and regions. In dry areas, no routine drenching is required at all! Do worm egg counts (WECs), but don't just rely on them in cattle. Sometimes they are a poor guide. Consider growth rates as well. If in doubt, do a 'diagnostic drench' on a small number of animals in the mob, and measure the response. If weaner cattle are held over until 15-18 months of age (summer/autumn), do a drench when they reach that age, mainly to manage type 2 (inhibited) Ostertagia. This drench should contain a 'mectin', or, even better, a combination drench containing a mectin and one or two other unrelated actives. Most importantly, use the drenches that you have tested and know work on your place. Drench-resistant worms are not just an issue for sheep, goats and alpacas.
Livestock may need another liver fluke drench in early spring. But for many, one fluke drench a year—in April/May, the single most important time to drench for liver fluke—will suffice. Seriously 'flukey' properties might need three, the 3rd fluke drench being in summer. Use the most effective flukicides at the April/May drench.
When you drench, make it a regular practice to do a 'DrenchCheck': a WEC on or just before the day of drenching, and another 10 days (sheep) or 14 days (cattle) later. Don't just monitor the older drenches; check the new ones (Zolvix®, Startect®) as well. Assume nothing. If checking a fluke drench, do a Fluke WEC on the day of drenching, and another 21–28 days later (all livestock species). Or you can do a 'faecal fluke antigen test', available through the Veterinary Diagnostics Laboratories at Charles Sturt University at Wagga.
Stomach fluke could be an issue for young cattle on swampy areas in some coastal areas. It rarely is an issue elsewhere. Get local advice.
Start thinking about preparing low worm-risk paddocks for weaner sheep.
No rain—could do with some though. The weather is really warming up out here and the growth from the July/August rains is in flower and burning off. No WECs have come through this month.
Few counts have come in this month. From what was received averages are 0–360 epg. Black scour worm has dominated those results where differentiation has been performed. Two incidental findings of barber’s pole worm were also found whilst on field visits.
Producers are reminded to undertake worm egg counts tests (WEC) especially if they are seeing increased scouring amongst their mobs (to help rule out worms vs. current feed on offer causing the scours). Fly strike preventative measures are beginning to be implemented for many producers as well.
With lots of fat lambs still on their mothers, worm burdens appear to be an isolated problem throughout the Wagga board at present. This is likely a combination of passive maternal immunity (from milk), and environmental conditions. However, as the weather is becoming milder, and rainfall continues, worms will be on the rise!
Producers should currently have plans in place for "clean" weaning paddocks and weaning drench use. Remember that a DrenchCheck—a worm egg count (WEC) 10–14 days post drench—is your best tool to identify if the drench was actually effective i.e. whether or not you wasted your money on an ineffective drench.
Further to this, if you have swampy paddocks or water ways that stock are able to graze, you should now be considering testing of faeces for liver fluke, as even the smallest level of fluke burden can cause significant production loss.
Worm tests that have come to our notice during August and September are quite variable. Of 17 tests two had an average strongyle count over 500, one had 100% barber's pole worm and the other 82% barber's pole worm; this second flock was experiencing deaths due to barber's pole in their 4-month old dorper lambs. Nine worm tests had high enough WECs to culture and there was a variation in proportion and types of worms present. Two thirds of the cultures identified a mixed burden of barber's pole worm, black scour worm and small brown stomach worm. Single enterprises that have tested different mobs have found a variation from 0 to very low egg counts in most mobs to an average of 800 epg in one mob.
What this tells us is that we can't guess what is happening with worms in your sheep; a worm egg count WormTest is a valuable tool to guide your worm control and management decisions going into the spring and summer. Watch the weather and watch your sheep.
In the west this month we have seen clinical coccidiosis causing a distinct tail and deaths in a weaning mob of wethers. Issues occurred after the lambs were paddock weaned in a confined area before being put into a new, larger paddock. A total worm count on a coccidian-affected weaner showed only eight worms in the abomasum and 200 in the small intestine, which is well below the 4000–6000 that is classed as clinically affected.
A few worm test results have come in this month, generally finding low levels of worms. Results have shown from between 0–256 epg strongyle worms with a larval differentiation on the highest reading showing 86% black scour worm, 13% small brown stomach worm and 1% large bowel worm. Rates of nematodirus eggs have varied from 0–120 epg.
In the east there have been no clinical cases of worms investigated and very few worm tests with results ranging from 60–228 epg strongyle and 0–40 epg nematodirus found. The results with the highest egg count also had a larval differentiation done, which found 77% barbers pole worm, 4% black scour worm and 19% ostertagia.
Black scour and/or brown stomach worms continue to be our major sheep issue. All classes of sheep have been affected, although lambing ewes and hoggets have been hardest hit.
Producers have been caught out by how quickly the problem has returned after drenching. Ewes given an effective pre-lamb drench have lost condition, become weak and died four weeks into lambing. And some mobs of hoggets have been struck down within five to six weeks of a drench. In many cases, worm egg counts are pretty low, and autopsies show high numbers of immature worms. Lambs-at-foot will pick up worm larvae off these heavily contaminated pastures, especially if the milk supply of their wormy mothers has been reduced. Don't delay weaning in these mobs, to ensure lambs are drenched and moved to a low-worm paddock.
To complicate things, some mobs (mainly hoggets) have developed a bacterial scour subsequent to worms. In these mobs, most sheep appear to recover following drenching for worms, while a significant tail continues to scour and look awful. Your vet may prescribe treatment with antibiotics in some cases.