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New South Wales worms, flies and lice update - June 2014

Armidale: Rad Nielsen, Veterinary Health Research (rnielsen@vhr.com.au)

Recent faecal egg count results from the New England region have tended to be in the moderate to low range. The mild autumn temperatures have been conducive to worm development; however, the general lack of rain has largely prevented them from taking advantage of this situation. This has not been the case in parts of the Central Tablelands, with reports of clinical haemonchosis and deaths, in conjunction with high worm egg counts (Haemonchus dominant infections).

Winter temperatures will prevent further Haemonchus development, however, producers need to be aware that existing larval pasture contamination will to a large degree successfully over-winter. Lambing ewes will be particularly susceptible to larval challenge and need to be managed with this in mind. Ideally, they should be placed in pre-prepared lambing paddocks and typically a confirmed effective drench administered a couple of weeks prior to the commencement of lambing. Worm egg counts and species determination can be used to confirm the need for drenching and fine-tune drench selection. Further testing at the completion of lambing will determine whether ewes require a drench at lamb marking and if, in fact, more urgent intervention is required.

It is important to be monitoring the worm egg count levels of all sheep at this time. Weaners may also be at risk of black scour worm infections, particularly if nutritionally compromised. Meanwhile, the drenching interval for adult sheep may be extended throughout the winter months given favourable worm egg count results. Sheep producers really need to be striving to minimise the use of anthelmintics in light of the deteriorating drench resistance situation.

A VHR worm monitoring client (from north of Glen Innes) submitted a kit this week (mid June), taken from Merino ewes. The sheep have not been drenched since late October yet only have a mean WEC of 128 epg. This has been achieved by adopting a rotational grazing system, combined with co-grazing with cows and calves. Equally surprising is the fact that their spring 2013 born lambs have not yet received a drench. Their most recent WEC (early June) was sub 900 epg (Haemonchus dominant) and the grazier reports that they are 'fighting fit'.

This example highlights that it is possible to create conditions in which sheep can perform in the presence of worms, yet without the use of intensive drenching typically associated with New England sheep enterprises. Producers in this region should particularly take note of the potential that exists to operate profitably and sustainably in such a low drench input system, where an increasing number are finding that they only have one truly effective anthelmintic active (monepantel) remaining at their disposal.

 

LOCAL LAND SERVICES DISTRICT REPORTS

Riverina LLS

Gundagai: Ian Masters, DV (ian.masters@lls.nsw.gov.au)

Very good autumn (spring-like) conditions. Things are ideal for a build up of worms but not too many issues to date. Have seen losses on a few holdings due to BPW but mectin resistance may have contributed to the problem: straight mectin based drenches used as second summer/early autumn drench. WECs are on the rise, but effective drenching and good feed has reduced the impact of worms on most holdings.

Narrandera: Gabe Morrice, DV (gabe.morrice@lls.nsw.gov.au)

In the western part of the Riverina most worm counts have been conducted in ewes with lambs at foot. Some of these showed high egg counts (up to 2000 epg). The majority of wormcounts have been undifferentiated, but when done, the diffs have shown mixed infections. The worm eggs being deposited now will largely survive over winter. Producers are encouraged to carefully consider the weaning paddocks they will use.

Wagga Wagga: Amy Shergold, DV (amy.shergold@lls.nsw.gov.au) and Tony Morton, DV (tony.morton@lls.nsw.gov.au)

Worm burdens have been highly variable in our region. A few farms have enjoyed consistently low results but in general numbers have increased. The highest counts were seen in mobs that have not received a drench since the autumn break.

Barber’s pole worm has caused losses reaching 5% in lambing ewes. Autopsies confirmed adult worms in the stomach and severe anaemia, which is a hallmark of infestation with this species. A couple of farms have had large burdens only two weeks after using a ‘mectin’ drench, suggesting resistance. This highlights the importance of doing a DrenchCheck 10 days after treatment.

On other farms, scour worms have been more of a problem, for example a recent test showed 402600 epg and species identification revealed a population comprised entirely of black scour and small brown stomach worms. Scouring is often attributed to lush feed this time of year, but sometimes worms are the cause.

Young: Rahul Shankar, DV (rahul.shankar@lls.nsw.gov.au) and Eliz Braddon, DV (eliz.braddon@lls.nsw.gov.au)

The month has seen increased worm egg counts by many producers. Wherever differentiation tests have been conducted, barber’s pole worm is the predominant (>90%) species detected. Some producers were part of the drench trial done a few years ago, so the increased counts have been attributed to pasture contamination (or residual contamination from an event that occurred a few years before) over drench resistance. Many producers have had to drench their mobs again (either as a pre-lambing drench or otherwise), but with the winter months hopefully upon us now we would expect to see decreased levels of worm burdens for the next few months. 

Rainfall has been steadily coming in throughout the region and would imply that any larvae left on the ground will be infective come spring time (late August/early September). All producers affected by current worm burdens have been reminded of this. 

South East LL

Goulburn: Bill Johnson, DV (bill.johnson@lls.nsw.gov.au)

Haemonchus (barber's pole worm) continues to cause concern for many flocks in the district. While the deaths have stopped for now, one question is frequently being asked: What do you use as a pre-lamb drench when egg counts have risen sharply to a couple of thousand, with more than 90% barber's pole? The answer depends on the recent history of the proposed lambing paddock. While no new eggs will hatch at present, any barber's pole larvae already on the ground will survive through winter. So if you are lambing onto a paddock contaminated since the autumn break, you may need a drench with sustained action against barber's pole. But if your lambing paddock has been spelled since the autumn break, a short-acting drench prior to moving ewes should suffice. Remember though, that we are increasingly seeing resistance of barber's pole to abamectin when used on its own. Be careful, too, when yarding heavily pregnant ewes prior to lambing—there have been some spectacular outbreaks of foot abscess recently, triggered by handling ewes in boggy yards.

While the winter scour worms have been pretty quiet so far, recent deaths of lambing Dorper ewes were due to black scour worms, and the proportion of brown stomach worms has been steadily increasing in some worm egg counts. You can avoid high-risk paddocks for lambing ewes from these worms this year by NOT lambing in any paddock grazed by any young sheep (weaners/hoggets) since the autumn break.

I saw a classic liver fluke outbreak in cattle this week, with weight loss, anaemia and bottle jaw. It serves as a reminder that winter is a good time to control fluke in cattle and sheep.

Yass: Alexandra Stephens, DV (alexandra.stephens@lls.nsw.gov.au)

Worm counts are generally slowly climbing during the late Autumn. Conditions in the pasture have been damp, moist and cool; excellent for larval survival. Worm counts and species cultures are proving very valuable as some individual properties are detecting large egg counts that are >96% barber’s pole in sheep that appear clinically well. The culture results are significant for both targeted drenching and pasture management in the spring. Some producers have become aware of the new Merial and VHR E-DNA worm test, and have found that receiving the species differentiation in 2–3 days rather than waiting 7–10 days for larval culture to be very helpful. 

Central Tablelands LLS

Molong: Alan Taylor, DV (alan.taylor@lls.nsw.gov.au)

Still getting average worm counts of up to 3,550 epg as there has been good rain and relatively warm conditions so far. Usually barber's pole, but one high count had 10% Ostertagia.

There must have been a special deal on Hat-Trick (presumably with nice steak knives) so have urged these producers to ensure that they did a follow-up wormcheck as all the Hat-Trick ingredients have been used around here for a long time.

Murray LLS

Deniliquin: Dan Salmon, DV (dan.salmon@lls.nsw.gov.au)

There has been good autumn rain over most of the Murray region. This means that any larvae on the ground now or deposited over the next few months will be available to infect sheep until October.

There has been a lot of enquiry about managing lambing ewe mobs but no clinical disease and generally low worm egg counts.