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New South Wales worm update - March 2013

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

The recent rainfall has seen a sharp rise in sheep worm egg counts across the New England region, Haemonchus being the main culprit. The worm challenge has been highest in set stocked situations, as would be expected. Mean worm egg counts (WECs) have been as high as 9300 epg in XB ewes (drenched 6 weeks prior with known effective drench). These were visually anaemic, however no deaths were apparent.

There are success stories to be found in respect to controlling Haemonchus, grazing management being the key component. An Armidale producer submitted a worm kit last week with a mean WEC of 54 epg, 3.5 months since adult ewes had been last drenched. Additionally, a Dundee grazier had Merino ewe hoggets with a mean WEC of 208 epg, in excess of 3.5 months since last anthelmintic treatment. In both cases, the sheep have been rotating through a series of paddocks (moved weekly and not returning for approximately 60 days). Cows and calves are also grazing the same paddocks (immediately in front of sheep). These examples show how worms can be ‘kept in check’ within a mixed grazing enterprise utilising a simple rotational grazing strategy.

LHPA DISTRICT REPORTS

Lachlan LHPA

Belinda Edmonstone and Nik Cronin, Forbes (Belinda.edmonstone@lhpa.org.au)  (nik.cronin@lhpa.org.au)

In the central area of the Lachlan LHPA average faecal egg counts for the month of February have ranged from 0–1040 with individual counts ranging from 0–1080. The dry summer has helped to keep worm burdens lower than the last few years. Barber’s pole worm is the predominant type on larval culture, however this appears to be restricted to irrigation country. It is time to do a worm test on pre-lambing ewes to determine if they require a drench before they are put on their lambing paddock.

Kasia Hunter, Condobolin (kasia.hunter@lhpa.org.au)

In the western area of the Lachlan LHPA only one WormTest was conducted during the past month. The results indicated a substantial parasite burden was present in the mob of weaner Merinos tested—the average faecal egg count was 752 (range: 0–1440). The predominant worm species present was Haemonchus, barber’s pole worm (89%), with low levels of Trichostrongylus (black scour worm) and Ostertagia (small brown stomach worm) also present. A moderate burden of Nematodirus (thin necked intestinal worm) was also identified in this mob. No stock losses have been reported during this month. Worm populations have the potential to increase significantly due to recent rain events across the area coupled with warm daytime temperatures and mild nights. Producers are urged to keep a close eye on their stock. A pre-autumn lambing WormTest (and drench, if necessary) is strongly recommended. If in doubt about the status of your sheep—WormTest!

Eliz Braddon, Young (eliz.braddon@lhpa.org.au)

The eastern end of the Lachlan LHPA has been quite actively worm testing in the past month. Most of these tests are checking the need for a second summer drench or in preparation for autumn lambing. In general, weaner mobs are at levels that will require drenching going into the winter, where as the adult sheep are fairing better. However, as usual, there is significant variation across farms dependent on when you last drenched and what sort of weather events you have had on your farm. So testing your sheep will give you the best answer as to your risk. Worm populations are generally mixed with all the significant worms. Of the 7 larval cultures done in February, all had Trichostrongylus (black scour worm) and Ostertagia (small brown stomach worm); and 6/7 have levels of Haemonchus (barber’s pole worm) present. As we approach April and weather remains warm, be aware that rainfall events could spark an ‘outbreak’ of barber’s pole so monitoring flocks for signs of lethargy, pale skins etc will be prudent.

Central West LHPA

Evelyn Walker, LHPA DV, Dubbo (evelyn.walker@lhpa.org.au)

Worms are present in the Central West area and average egg counts received this month vary from farm to farm. The majority of egg counts are overall low ranging from 80 to 300. However, one farm with heavily pregnant ewes had an average egg count of 1060 consisting of 85% barber’s pole worm and the remaining a mix of black scour and small brown stomach worms.

In contrast, the dry ewes on this same farm only had an average egg count of 300. Both mobs were drenched at the same time last year. This is a good example of how pregnancy can affect the ewe’s ability to fight off worms. The ewe is putting in so much effort to look after her lambs in late pregnancy and during lactation; her immune system is temporarily lowered against worms—referred to as ‘periparturient relaxation of immunity’. This relaxation of immunity causes higher faecal egg counts and subsequently leads to higher pasture contamination and exposure of young lambs to worm infection.

Since this farmer completed his WormTest in time, he was able to treat his pregnant ewes and avoid a potential disaster. A friendly reminder to us all: WormTest pregnant ewes a month before lambing. And if egg counts warrant it, you can drench at the same time as vaccination. This way, you are ensuring optimal health for both your pregnant ewes and their lambs.

Tablelands LHPA

Bill Johnson, Goulburn, (bill.johnson@lhpa.org.au)

Nematodirus (thin-necked intestinal worm) is causing scouring and some deaths in lambs. Outbreaks can be quite explosive, escalating from a few to a significant number affected within a week. Worm eggs of Nematodirus tend to hatch en masse after a decent autumn rain event, about the same time as the green pick becomes useful. Worm egg counts often don’t tell the whole story, as scouring usually begins before the worms are old enough to lay eggs. A post mortem of a crook sheep helps, as there are a couple of bacterial infections also causing scouring in lambs at present, including salmonella. It may be just the green feed causing the scouring, but you need to rule out other causes, especially if they have lost bloom.

Conditions have been perfect for barber’s pole worms since the earlier rain, warm days and heavy morning dew. If you had evidence of them on your property the past year or so, continue to do worm egg counts more frequently, as they can build up quickly.

Remember that liver fluke symptoms are similar to those of barber’s pole (weak, fatigue easily, pale skin from anaemia, fluid swelling under the jaw). Fluke numbers increased in sheep during the dry summer in mobs with access to creeks and swampy areas, and will begin to impact over the next couple of months.

Charlotte Cavanagh, Veterinary Officer, NSW Department of Primary Industries, Bourke (charlotte.cavanagh@dpi.nsw.gov.au)

The pasture conditions in the Darling LHPA area are sparse and dry and some producers are battling to keep water up to their stock. The daily temperatures are still averaging in the mid-thirties. There have been no worm tests submitted in the past month.

Riverina LHPA

Gabe Morrice, Narrandera (Gabe.Morrice@lhpa.org.au)

A property WormTested its Dorper and Merino ewes in late October and found both to have very low egg counts. The owner retested both mobs in late February and the merinos had an average strongyle egg count of 52, whereas the Dorpers had an average egg count of 5192 (with a range of 120 to 28600 epg. Typing found this to consist of 89% Haemonchus). The two mobs had been running on separate properties and the Dorpers were on a neighbour’s place where this is no set drenching program and often ineffective drenches are used. The area had received a storm 3 weeks before the test with approximately 18ml rain falling. The Dorpers had then focussed their grazing on the green pick that came up. Very few clinical signs had been observed other than slight diarrhoea when they initially started on the green pick.

Several other WormTests have been conducted over the past few weeks and these have ranged from average counts of 16 to 184 epg (this latter one 75% Trichs and 25% Ostertagia).

Producers are encouraged to test their sheep, particularly if they have been under some rain prior to the cooler weather setting in.

Colin Peake, Hay (Colin.Peake@lhpa.org.au)

The egg counts are picking up in the western Riverina, but still not a lot.

A few in weaner sheep have come in on the borderline when considering a drench with epgs around the 150 to 190 mark. This is interesting after the long hot dry summer we have had.

There has been one very high count with lambs on an irrigation block, some dying, others with obvious clinical disease. The counts were up to 42000 epg, Haemonchus being the problem. Drenched and a 10–14 day post drench WEC performed with a zero epg. No drench resistance here yet! An abnormal occurrence at Hay, but this does show that worms can be a problem anywhere. Conditions still very dry here, Producers should test in the Autumn if they are concerned with their sheep or want to know what their worm burden is.

Dan Salmon, Riverina (dan.salmon@lhpa.org.au)

We have had quite a few egg counts as we head into the late summer and most of them are very low with an occasional high one.

One group of interest is a mob of sheep that were lambs in 2011 when the worms were so bad and have had high egg counts last year and this year even though they were given an effective drench and run on relatively low-risk pasture and yet their older and younger sisters continue to have low egg counts.

There have been a few flocks with Haemonchus, which must have survived one of the driest 12-month periods on record as well as a significantly hot and dry summer. This includes a mob of weaners which had low egg counts early in the summer and had been rotated on large (>1500ha) paddocks that were anaemic and losing weight with a few deaths two weeks after 70mm of rain in early March.

North West LHPA

Fiona Fishpool, LHPA, Moree (fiona.fishpool@lhpa.org.au)

There have been no clinical cases around Narrabri, Moree or Walgett. In these areas there have been a number of enquiries in regards to worm management. Producers are advised to WormTest and base decisions on a flock-by-flock basis as WECs have been low to moderate with most below levels requiring action. Meanwhile WEC’s have been high throughout the eastern side of the district and now is an ideal time for a long acting drench, leading into winter. The recent wet conditions around Narrabri and Moree do increase the possibility for autumn pasture contamination with Haemonchus eggs. This could cause problems if we get a wet spring. There has also been a couple of higher than usual Nematodirus counts in the western area, which should be watched where there has been rain following a dry spell.