WRML.2015-04-23. Wormfax. High Haemonchus counts. Targeted treatment.Snapshot-lamb industry+DPI input.WA threatens secession.

WormMail(WRML).2015-04-23. Wormfax. High Haemonchus counts. Targeted treatment.Snapshot-lamb industry+DPI input.WA threatens secession. In this issue:

  • WormFaxNSW March 2015
  • A case for Worm Testing and DrenchChecks (Jim Kerr) incl. Resistance Survey (Playford et al)
  • Targeted / selective treatment – some thoughts (Johann Schröder)
  • Snapshot of Australian sheep and lamb industry (+ DPI input) – MLA report
  • Western Australia threatens to secede

WormFaxNSW-March 2015 For more information on WormFax – and for the full results – go here: http://www.dpi.nsw.gov.au/aboutus/resources/periodicals/newsletters/wormfax In the table below are some highlights: Table. Highest Sheep WormTest results around the traps – NSW, March 2015

Lab Area of NSW(LLS, former LHPA etc) Sheep class WormTest Mean egg count (strongyle) Range Haem Trich
V Northern New England Ewes 12368 600-21600 100%
Armidale Wethers 19516 2600-37000 94% 6%
V Northern Slopes Lambs 7492 1880-13280 100%
E North West 564 200-1400 100%
V Moree Weaners 916 240-1520
V Tamworth Ewes 2808 0-11560 98% 2%
E Central West Mer. wethers 14600 100%
V Coonabarabran Lambs 4488 1640-12920 97% 2%
V Mudgee Ewes/lambs 7832 320-19040 100%
V Forbes Lambs 1532 0-4640 100%
V Dubbo Lambs 2712 1360-3960 99%
Hunter Lambs 4804 720-8240 100%
E Central Tablelands Hogget ewes 3620 1640-5600
E Greater Sydney Ewes 4424 0-19200 96% 4%
V Moss Vale Weaners 1680 920-2960 95%
E Western Mer. Ewes 940 920-960 99% 1%
V Yass Ewes 6028 0-13680 99%
V Young Lambs 4224 800-6920 97% 1%
E ACT 220 80-360
V Gundagai Mxd 6164 120-14480 99%
E South East Ewes 6100 800-11400
V Cooma Weaners 3896 320-8920 100%
V South Coast Weaners 4448 840-18400 27% 71%
V Hume Weaners 14832 6400-24720 100%
Murray Ewes 408 40-880
E Riverina 3760 2200-5320 97% 1%

Notes: E=EMAI=Elizabeth Macarthur Agric. Institute (Menangle). V=VHR=Veterinary Health Research (Armidale). LLS=Local Land Services. LHPA=the former Livestock Health and Pest Authorities (now part of LLS). Haem=Haemonchus (barber’s pole worm). Trich=Trichostrongylus (black scour worms). Tel=Teladorsagia (small brown stomach worm. Larval differentiation results for Tel. not included: they were found in just a couple of cases and at 1-2%). There was a smattering of positive Fasciola (liver fluke) egg counts, mostly through tablelands districts.

Bear in mind that, for most ‘flukey’ farms in NSW, April-May is the single most important time for a strategic fluke drench. A standout in the results for March was some high Haemonchus egg counts in various parts of the state.  There was very good rain in many parts of NSW in December and January, before returning to the trend of below average rain in February and March. It would appear the good early to mid-summer rain was enough to kick Haemonchus along. But again the perennial question: how many got caught because they do not do regular WormTesting, and how often was a worm problem exacerbated because drench efficacy is so often left unchecked? Note the high count (mean of 4448) from the South Coast LLS where the larval culture was dominated by Trichostrongylus. Sometimes Trichostrongylus can produce reasonably high WECs; not high by Haemonchus standards (but, WECs in that WormTest did range up to 18400!), but reasonably high nonetheless. Young and older players have been caught by this before: a high-ish WEC and have eschewed a larval culture, assuming Haemonchus to be the cause, and have opted for a narrow spectrum drug like closantel.

Now, speaking of high WECs: the highest I recall for Haemonchus was ~ 121,800 epg (EMAI vet Mel Gabor handled that case), but even more spectacular in a way was a case out Bourke way, handled by field veterinarian Kylie Greentree (now at greener pastures in the Hunter). In Kylie’s case, the epg was ~ 60,000 – BUT!! – it was Trichostrongylus (yes, the larval differentiation result was double-checked), not Haemonchus. More details here: https://wormmailinthecloud.wordpress.com/tag/dpi-role-in-major-award/

Case study – a good reason to WormTest and DrenchCheck Dr Jim Kerr, Wingham-based District Veterinarian for the Hunter Local Land Services, told me of deaths he investigated in 6-8 month old Dorper lambs in the Gloucester area of NSW. Five out of 13 lambs died in February. They had been drenched with Q-Drench® (abamectin + albendazole + levamisole + closantel) in February, then again on 15 March. Two more died after the mid-March drench and another two were pale. They were mostly set-stocked, i.e. mostly grazed the same paddock. Faeces from 8 lambs were submitted to the lab on 7 April, approximately 3 weeks after the last Q-Drench. The average strongyle egg count was 17,760 eggs per gram of faeces (epg), with individual counts ranging from 80 to 70,000 epg. The prepatent period for Haemonchus can be as short as 18 days, and these samples were collected about 23 days post-drench, but I think it can be safely assumed (drench maladministration etc. aside) that Haemonchus on this property is resistant even to Q-Drench and each of its constituents. All this of course could have been simply avoided through regular WormTests and periodically checking drench efficacy with a WormTest after drenching (DrenchCheckDay10). Although called Homo sapiens (‘wise man’), we humans are not always super-smart. Consider this graph below, a partial summary of a survey of drench resistance in Australia published by Playford and others in December 2014. Figure. Percentage of tested sheep farms with drench resistance (Australia, 2009-2012) graph % farms with resistance Playford et al 2014

Notes: BZ=benzimidazole, ‘white’. LEV=levamisole, ‘clear.’ MPL=monepantel (‘Zolvix’, an ‘AAD’. No resistance detected).The macrocyclic lactone (ML, ‘mectin’) drenches are: IVM=ivermectin, ABA=abamectin, MOX=moxidectin. BZ/LEV etc. are combination drenches. CLOS=closantel. *Less than 50 usable drench tests for this drench. ‘Resistance’ here means the worm egg count reduction after treatment was <95% for one or more of Haemonchus, Trichostrongylus or Teladorsagia species. Reference: Playford MC, Smith AN, Love S, Besier RB, Kluver P and Bailey JN, 2014. Prevalence and severity of anthelmintic resistance in ovine gastrointestinal nematodes in Australia (2009-2012). Aust Vet J 2014; 92: 64-71. Consider the graph and the case study: ‘good reason to do regular WormTesting and DrenchChecks, don’t you think?

Targeted / selective treatment of sheep – some thoughts from Dr Johann Schröder “Thank you for another informative and thought provoking WormMail.  Lewis’ piece on targeted selected treatment in the SRZ (summer rainfall zone) set me thinking. After many years as a successful livestock veterinarian in the Eastern Freestate (South Africa), Francois (Faffa) Malan was working for a pharmaceutical company in the late 1980s / early 1990s. He investigated a drench efficacy complaint in the Eastern Transvaal (Mpumalanga province on today’s map of the country) and discovered a big Haemonchosis challenge, but also fairly solid resistance to most chemicals available at the time. In order to reduce the producer’s reliance on chemicals, he suggested treating only the worst affected animals and selected them on the basis of their degree of anaemia, judged by the colour of their conjunctivae. This method seemed to halt further mortalities, saved the farmer a fair bit of money in chemicals and didn’t result in undue production losses. To underpin his recommendation with some scientific rigour, he proceeded, with the help of Gareth Bath (at the time professor in production animal medicine at the Onderstepoort vet school) to produce a set of photographs of graded conjunctival colouring. Thus was the FAMACHA (FAffa MAlan CHArt) born.  I sat in the audience of the sheep vets conference in Armidale in 1997 when Gareth presented this idea, which was promptly rejected by the Aussies, because it was too labour intensive. The labour intensity of the technique remains, because animals need to be FAMACHA’d regularly in summer to avoid acute large scale mortalities. But it is also true that in a country where most sheep production occurs in a summer-dominant rainfall zone (the WRZ (winter rainfall zone) in South Africa is confined to a narrow coastal strip stretching about 1,000 km eastwards from Cape Town), FAMACHA has provided some measure of relief to sheep producers blighted, as we are, with drench resistance.  All the best  Johann Schröder” Lewis’s piece can be found here: https://wormmailinthecloud.wordpress.com/2015/04/14/wrml-2015-04-14-partial-flock-treatment-in-summer-rainfall-areas-aus-devil-in-the-detail-new-tech/

Snapshot of sheepmeat and other industries by MLA – and NSW DPI’s role MLA has published an interesting and well-presented snapshot of the lamb industry. It’s worth a read. http://www.mla.com.au/files/edcbf4da-3cf0-4859-9712-a475010b8dae/MLA_Real-Sheep-Prices-Publication_09-04-15.pdf   or http://preview.tinyurl.com/pd4vw32

One of the key points: “The birth of the specialised meat sheep industry in Australia assisted a recovery in prices after the wool crash, generating increased global demand for higher quality lamb”. NSW DPI, along with others, has played an important role in the development of the sheepmeat industry. Past and current employees of NSW DPI who were involved include:

Past:  Bill O’Halloran, David Hall, Brent Mcleod,  Barry McDonald, Chris Shands,  Peter Holst, Geoff Duddy,  Neal Fogarty, Andy Kajons, Alan Luff, Dave Harris. Doing research in support of the resurrection of the lamb industry, there was Arthur Gilmour in particular and also Kevin Atkins, who did early work on developing Lambplan.

Current: David Hopkins, Ashley White.

This is by no means a complete list of players, but some of those with whom DPI worked closely in this area were Arthur Gates, Laurie Thatcher, Ron Harris, David Kingham, Ian Johnsson, Gerald Martin, Rob Banks, various NSW lamb processors and producer groups.

Western Australia threatens to secede http://www.theshovel.com.au/2015/04/13/western-australia-threatens-to-secede-from-rest-of-reality/ SL, 2015-04-24

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WRML.2015-04-14. Partial flock treatment in summer rainfall areas (AUS)? Devil in the detail. New tech.

To WormMail mailing list (recipient undisclosed)

 In this issue:

  • Early thoughts on partial flock treatment in summer rainfall regions (Australia) – Kahn
  • The devil may be in the detail (reading science reports)
  • Some new diagnostic technologies (R Woodgate)
  • Diarrhoea (Casburn)

Hopefully most of you receive ParaBoss news and read it. If not, you miss out on goodies like the article below by Lewis Kahn.

You can subscribe at the WormBoss or ParaBoss websites.

For further information on topics raised in Lewis Kahn’s article, go to WormBoss.com.au: things are easy to find there.

Early thoughts on partial flock treatment in summer rainfall regions (Australia)

by Lewis Kahn, ParaBoss Executive Officer

ParaBoss News March 2015

http://www.wormboss.com.au/news/articles/drench-resistance/early-thoughts-on-partial-flock-treatment-in-summer-rainfall-regions.php

The rise of drench resistance

Many sheep producers have heard of partial flock treatment (targeted treatment), which is the concept of leaving a proportion of a mob of sheep untreated as a means to slow the development of drench resistance. Why this is of interest requires some thought about how drench resistance develops.

Where drenches are not fully effective, the eggs passed in dung are all from worms that survived treatment. That is, they are the eggs of the drench-resistant worms that remain in the sheep. Even with new treatment actives, drench resistance might already exist, just by chance, in a tiny proportion of the worm population. So even then, the very few eggs—often way too low in number to detect in laboratories—that are passed in dung after treatment are likely to be those from drench-resistant worms.

So, drenching is a process of selection that sees a gradual increase in the proportion of drench-resistant worms, and subsequently, drench efficacy falls. Of concern is that by the time a DrenchTest indicates 95% drench efficacy (that is, when worm egg count is reduced by 95%), the genes in that worm population that code for susceptibility to a particular drench active have already declined to 75%; with 25% now being for drench resistance.

Good drenching practices

To slow the development of drench resistance, WormBoss recommends quarantine treatments and 5 important actions when using drenches.

  1. Use drenches most effective on your property. Ideally use those that are at least 98% effective, as shown by a DrenchTest. This is especially important for strategicsummer drenches in winter rainfall (including Mediterranean) regions.
  2. Use a combinationof two or more drench groups.
  3. Use short-acting treatments, only using persistent productsfor specific purposes and high worm-risk times of year.
  4. Rotate among all effective drench groups each time a mob is drenched (and for each paddock).
  5. Calibrate drench guns to ensure the correct dose is delivered, which is calculated on the heaviest animals in the mob. Split mobs for drenching if there is a large weight range.

 Risk factors

An important risk factor for development of drench resistance is the number of worm larvae on pasture when the sheep are drenched. These larvae are often referred to as being in refugia because they are in refuge from (not exposed to) the drench. Where partial flock treatment (also called targeted treatment) is used, that is, leaving a proportion of a mob undrenched, the worms in undrenched sheep are also in refugia, as they also have not been exposed to the drench. As the worms in these sheep have not been selected for resistance—the level of both susceptible and resistant worms they had before their flock-mates were drenched are still present—the eggs that pass in the dung from these undrenched sheep can help to offset the predominance of eggs from drench-resistant worms in the drenched sheep.

When a pasture has a relatively low level of worm larvae and the drenched sheep are grazed there, the pasture will become increasingly contaminated with eggs from resistant worms, as they are the only ones that survived the drench. This is likely to increase the proportion of drench-resistant larvae that subsequently develop on the pasture and go on to infect sheep, resulting in a more rapid increase in drench resistance.

In contrast, when the number of worm larvae on the pasture is high, eggs shed in dung from resistant worms will make up a small proportion of the population, with a slower increase in drench resistance.

So, strategies to maintain worms in refugia inside the sheep are likely most important where the environment and management practices result in periods where the number of worm larvae in refugia on pasture fall to very low levels. This might typically include the Mediterranean region during its hot, dry summers, but also, to some extent, the summer rainfall tablelands region of NSW after its long, cold winter. In the WormBoss regional program for Western Australia, adult ewes are drenched in autumn instead of summer to avoid drenching when there are few or no larvae in refugia on the pasture.

Partial flock treatment in summer rainfall: some early thoughts

The concern for using partial flock treatment in any region has been loss of production. This has been shown to be negligible for Merino ewes in Western Australia and for cross-bred ewes in winter rainfall regions of Australia. However, where barber’s pole worm is common, the concern is sheep deaths, rather than body weight or fleece weight loss.

In summer rainfall tableland and slopes regions, the most effective time to leave a proportion of adult ewes undrenched so as to maintain worms in refugia is during spring, after the long and cold winter. During winter, barber’s pole worm is unable to develop from egg to infective larvae, so the number of larvae on pasture at the beginning of spring is low. However, lambing is often in spring, and lambing ewes suffer a decline of their natural immunity to worm infection. This alone could be a deterrent regarding leaving some sheep undrenched.

Nevertheless, the concept of partial flock treatment needs to be seriously considered because of the prevalence and severity of drench resistance in the region.

Meat and Livestock Australia are currently funding the Lifting the Limits project that is determining the production cost of worms in cross-bred flocks and identifying best practice worm control. This involves 17 farms from the northern tablelands of NSW through to Victoria, with similar flock experiments in Western Australia. In the northern tablelands of NSW, this project provided the opportunity to see if ewe body condition score can be used to select the most suitable cross-bred ewes to leave undrenched as part of a partial flock treatment. Body condition score was used as a possible trait because it is a subjective measure of whole body muscle mass that is known to benefit the sheep’s resistance to worms.

Experimental results

The large dataset* collected from twin-bearing Border Leicester x Merino ewes during the three years of the Lifting the Limits experiment showed that worm egg count (WEC) was favourably associated with body condition score (BCS). In other words, at any point in time from pre-lambing to weaning, fatter ewes (higher BCS) were more likely to have a lower worm egg count. On this basis, the fatter ewes seemed to be the best ewes not to drench, so as to maintain a proportion of the worm population in refugia to slow development of drench resistance.

body condition score vs wec Kahn 2015

Figure 1: Worm egg count (average ± 68% confidence intervals) of cross-bred ewes based on body condition score category during the period pre-lambing to weaning.

But the real question remained, would those ewes with higher pre-lambing body condition scores continue to have lower WEC up until weaning? The results in the figure above indicated that higher BCS ewes had a lower WEC at any point in time, but they did not indicate what the future held for these ewes.

Unfortunately, pre-lambing BCS was not predictive of subsequent WEC at marking or at weaning and this means it is unlikely to be a useful tool for identifying the pre-lambing ewes that can safely be left undrenched.

The reason why body condition score (BCS) did not indicate future WEC was because those ewes in the highest BCS just prior to lambing lost the most condition over the lactation period. These ewes likely transferred body condition to milk and more successfully reared twin lambs. The downside for these ewes was that loss of BCS at this time was associated with an increase in WEC.

In summary, the results indicate that ewes in better body condition score prior to lambing are likely to have lower worm egg counts initially, but do not maintain a lower WEC because they lose more condition.

At this stage, the safe use of partial flock treatment in summer rainfall tableland and slopes regions doesn’t seem possible. This is because of the risk of deaths from barber’s pole worm and the absence of a trait that can readily be measured or assessed to allow real-time and within-yard decision-making on which animals could remain untreated.

These are only early thoughts and WormBoss will continue to keep a close eye on this topic.

*The data collected were from 120 Border Leicester x Merino ewes on each of 3, 5 and 5 properties during the years 2012, 2013, 2104 respectively in the Armidale region, New South Wales. Body condition score (BCS; 1–5 scale) was estimated and faeces collected to determine worm egg counts (WEC). Adult ewes were identified as twin-bearing. Lambing occurred in September of each year. Measurements were done at pregnancy scanning (July), prelambing (August), lamb marking (November), weaning (January) and mating (April). Prelambing, lamb marking and weaning data were used for this analysis. There were 3,989 observations with both BCS and WEC recorded.

 The devil may be in the detail

When scientists do and report research, they sometimes make mistakes, and they may draw dubious conclusions. We’re all human. Humans are the weak link in the scientific process.

Then science gets reported in the media. Some science reporters are doubtless very good at critically reading published scientific papers. Others, not so much. Time-strapped reporters and readers may just rely on the abstract and the authors’ conclusions. But, the devil may be in the detail.

Some time ago the ABC – and others – reported on a study thusly:

“Eating a high-protein, low-carb diet could actually make you unhealthy and more likely to die younger, a landmark Australian study has found”.

http://www.abc.net.au/news/2014-03-05/low-carb-diet-may-shorten-your-life-study-finds/5299284

The article continued: “The three-year study by the University of Sydney’s Charles Perkins Centre found that while high-protein diets might make you slimmer and feel more attractive, the best diet for longevity is one low in protein and high in carbohydrates”.

“Professor of geriatric medicine David Le Couteur from Sydney’s Anzac Research Institute was part of the team which modified the diets of 900 mice with dramatic results.”

So, a landmark study from experts from a prestigious institute. Watertight, eh?

I decided to check further. I couldn’t get access to the journal (Cell Metabolism) in which the paper was published, but I found this colourful critique at ‘Hyperlipid’ (URL below), written by British veterinarian, Petro Dobromylskyj. (OK, he is a British veterinarian, but don’t hold that against him: the bit about being British I mean).

Here is the critique at Hyperlipid:

“In the same Aussie pile of wallanga purporting to report science there was a slightly more interesting study published by Le Couteur et al using the standard crippled C57BL/6 mouse strain. They fed umpteen macronutrient ratios to umpteen mice and looked at the longevity. Remember, you cannot feed butter to C57BL/6 mice. Saturated fats break their brain; they have problems with their peroxisomes and with their first phase insulin response, so they in no way resemble any but the most unfortunate of human beings. Feeding them saturated fat is out unless you feed them a ketogenic diet. With that said, enjoy the last comment in this quote from the group:
‘Although the mice on a high-protein diet ate less and were slimmer, they also had a reduced lifespan and poor heart and overall health. Those on a high-carbohydrate, low-protein diet ate more and got fat, but lived longest. The mice that ate a high-fat, low-protein diet died quickest’.

Executive summary: Fat = death.

A brief trip to supplementary data gives what the diets were made of:

“Diets varied in content of P (casein and methionine), C (sucrose, wheat starch and dextrinized cornstarch) and F (soya bean oil)”.

The only fat used was soya bean oil. Can I emphasise again, as many times before: DO NOT CONSUME BULK CALORIES AS PUFA (polyunsaturated fatty acids), ESPECIALLY OMEGA-6 PUFA.

A free “did you notice that?” snippet: Protein was “casein and methionine”. Methionine restriction has been shown to prevent metabolic syndrome and possibly to extend lifespan. If you wanted to show protein was bad, might you spike casein by adding extra methionine? To complement the PUFA induced fat-badness??? How do these people sleep at night?”

http://high-fat-nutrition.blogspot.com.au/2014/03/would-you-like-soya-oil-poured-over.html

My point in discussing this example is not to say who is right, but rather to illustrate that there may be more than one interpretation, scientists and journalists are human too and don’t always get it right, and the devil may be in the detail.

By the way I don’t know what ‘wallanga’ means. There are Australian placenames that sound almost like that. Either way, I don’t think it is complimentary.
‘Doveryai no Proveryai ‘   (Trust, but verify)

 Some interesting new diagnostic technologies

Just for interest, here are some interesting new technologies Dr. Woodgate of CSU shared with me:

http://www.gizmag.com/tattoo-metabolic-skin-sensor/25327/

http://www.gizmag.com/bio-ink-sensors/36363/

http://www.gizmag.com/rhode-island-university-paper-based-mini-lab/36481/

http://www.gizmag.com/nanoprobes-nist-gem-biosensing-magnetic-fields/36803/

Diarrhoea

From my colleague, G Casburn:

‘Diarrhoea is inherited – it runs through your jeans’.

 

SL, Armidale. 2015-04-14