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New South Wales worm update - December 2013

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

The worm situation in the New England is somewhat varied. Paddocks which had been destocked of sheep just prior to the November rain (or were running recently drenched sheep) appear to have very low levels of infective larvae at this time. The dry conditions in early spring prevented any larval development over that period and overwintering larvae have either been ingested or have died through natural attrition.

Conversely, paddocks in which eggs were actively being deposited during the November rainfall events are now potentially heavily contaminated with worm larvae, placing sheep at risk. Short paddock feed will also be a contributing risk factor, preventing any “dilution” of larvae. High worm egg counts are now being seen in sheep run under such circumstances, likely leading to high frequency drenching. The standard summer message of combining regular worm monitoring with close observation of sheep should be applied despite the fact that seasonal conditions are very marginal across the majority of the district.

Producers to the west and south are dealing with a particularly dry time. Worm burdens in sheep are low to negligible in many cases. Unnecessary drenching can be avoided by worm monitoring, saving both time and money as well as preventing further selection for drench resistance.

I wish all WormBoss readers and VHR clients a Merry Christmas and prosperous New Year!

LHPA DISTRICT REPORTS

Lachlan LHPA

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

Five WormTests were performed in the central area of the Lachlan LHPA during the month of November with average faecal egg counts ranging from 0 - 860. Individual counts range from 0 – 1120. Generally worm egg counts remain low. If dry conditions continue, perform a WormTest before drenching to determine whether drenching is required.

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

In the western area of the Lachlan LHPA, monitoring for worm activity has been less of a priority with most producers in this area currently occupied with harvest activities. There have been no reports of worm-related clinical disease or deaths in livestock.

Elizabeth Braddon, Young (Eliz.Braddon@lhpa.org.au)

In the eastern area of the Lachlan board, worms have been less of a focus.  However, the twelve WormTests that were received were mostly done on ewe and wether mobs and indicated that most mobs are fairing very well in terms of worm burdens.  The average across all mobs was 214 epg with a range of 20-540 epg.  If this is the summer DrenchTest, then most of these mobs will require a drench to get levels below the trigger point and allow for the summer’s heat to clean up the remaining pastures of worm eggs.  There is some low level Haemonchus (Barber’s pole worm) lingering in the background of the differentials (eg. under 15%) that may gain some ground on the resistance front if producer’s are not careful of the drench choices they are making.  In general though, compared to the last few summers, it is looking like worms will be less of a problem unless we get some significant summer rains.

South-East LHPA

Bob Templeton, Braidwood (Bob.Templeton@lhpa.org.au)

It’s been a bit quiet around Braidwood.  Since the dry weather started the Barber's pole worms have dropped back to be replaced by either Black scour worm or Small brown stomach worm (a surprise).  I expect the Barber’s pole to quickly build up if we get any more rain.  Their effect will be seen in the autumn. 

A December liver fluke drench would not be out of place.

Tablelands LHPA

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

Several days of hot drying wind and only light patchy rainfall brought an abrupt end to the spring. As a result, worm larvae are dying at a great rate in most paddocks across the district. With this in mind, there is now a good opportunity to clean up a paddock or two that will be used by weaners after the autumn break. Select those paddocks which have pasture species capable of responding quickly to summer storms and autumn rain; graze them heavily now with drenched grown sheep to open up the pasture to sunlight, then destock them in anticipation of getting some quality green feed with low worm levels in a couple of months.

WormTests are still showing a significant proportion of Barber’s pole worms in sheep across the district. But without decent rain, these are not expected to cause problems. The exception will be in sheep grazing paddocks with low-lying areas like creek flats which stay green. In the past, we’ve seen sheep continually hammer these green patches at artificially high stocking rates over summer. Dorpers have more commonly featured in this scenario with Barber’s pole worms causing anaemia and deaths.

Hume LHPA

Tony Morton, Wagga Wagga (tony.morton@lhpa.org.au)

Counts continued to be variable and many had some Barbers pole worms despite the dry November conditions. In some cases October /November drenches saw very little reinfection - in others there was significance reinfection for example:

  • One producer had a mob of ewes with a burden of 98% BPW, av. 380 epg (range 0-1840). This mob received a first summer drench in early November with an effective product.
  • Another producer drenched lambs at weaning in late October with an effective product and put them on well selected paddocks. Despite that management, sufficient reinfection had occurred by mid December that a first summer drench was necessary.  The aim of Drenchplan is to minimise pasture contamination over summer and early autumn

Where a summer drench was given early, monitoring is advisable to assess re-infection rates and an additional drench may be needed.

A drench resistance test revealed Abamectin was only 36% effective against Barber’s pole worms but fully effective against Small brown stomach worms and Black scour worms. When combined with white and clear an excellent kill of all species occurred. Another example of triples delivering good results in local flocks.

New England LHPA

Andrew Biddle (Andrew.Biddle@lhpa.org.au)

The Inverell area is on the cusp of a season. Variable rainfall interspersed with hot days has led to a huge variation in internal and external parasites.

Those who have received the rain are seeing a typical spring rise in BPW with most direct enquiry to me as a result of unsuccessful drenching due to drench resistance. Farmers who have relied heavily on Moxidectin are coming to terms with increased resistance and the need to use other drench groups.

Further east around Glen Innes, rain has been more typical and widespread so worms are more plentiful. Farmers need to be monitoring and managing larval contamination of pasture to avoid a New Year BPW crash.