WRML.Breed for resistance and/or resilience ?

To WormMail mailing list (~ 400 subscribers; recip. undisclosed). WRML.2014-04-16

In this issue:

Resistance vs resilience.

Also: fasciolosis in humans; FWEC course in Tamworth (and elsewhere); Jet lag – there’s an app for that; Phubbing; Easter Road Safety; Moron multitasking.

Resistance vs resilience

Host genotype has a big impact on worm control. A question that sometimes arises is, ” should I select sheep for resistance to worms, or resilience?”

The following, a media release from the Sheep CRC, addresses the question.

“Breeding for resistance best insurance against worms

Sheep breeders pursuing worm ‘resilience’ rather than ‘resistance’ could be placing undue pressure on their sheep during the current dry seasonal conditions.

According to Executive Officer of the WormBoss program, Dr Lewis Kahn, sheep breeders selecting better grown sheep are indirectly selecting for worm ‘resilience’ but this does not improve worm ‘resistance’ because they are separate traits.

“Resilient sheep are those that grow and perform well despite infection from parasitic worms, whereas resistant sheep have a lower level of worm infection because of a better immune response,” Dr Kahn said.

“Resilience is difficult to measure because it is the difference in production between worm-free and when infected, and represents the cost of worm infection.

“And while resilience in sheep is desirable, it has a very low level of heritability, with little benefit passed to the next generation of the flock.”

Dr Kahn said worm resistance was considerably more heritable and could be improved by using Australian Sheep Breeding Values (ASBVs) for faecal worm egg count (WEC).

“Where producers are selecting sheep for production under normal levels of worm challenge, research has demonstrated that this will also select towards worm resilience,” he said.

“In contrast, worm resistance doesn’t come from selecting for production and needs to be separately considered.

“While ‘resilient’ sheep may be little affected by their own worm population, the worm eggs they deposit in faeces onto pasture provide contamination attacking the susceptible sheep.

“And when the chips are down and feed is short, like it is in many areas at the moment (February-March 2014), resilience is greatly diminished and these sheep are less able to cope with the additional stress of parasites.”

The WormBoss program was developed in 2005 by the Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC) and Australian Wool Innovation (AWI).

Since then the WormBoss website, www.wormboss.com.au, and the WormBoss training workshops have been delivered to producers and industry advisers to help industry to reduce the cost of worms through tactics including grazing management, breeding for worm resistance, managing for production targets, using effective drenches and managing drench resistance.

“Commercial sheep producers can identify candidate sires for purchase based firstly on the productive traits they need and then from within this group purchase those with the most negative WEC ASBV. This ensures both productive and worm resistant sires and excludes those sheep where resistance comes at the expense of production,” Dr Kahn said.

It’s an approach supported by the President of the Australian Association of Stud Merino Breeders, Phil Toland, who said that while more research was needed into how sheep and worms interact, the current evidence was clear that the best insurance for a sheep flock against worms was to breed for resistance.

“I hear breeders saying they have sheep with high egg counts that are their best doers in their flock and are therefore resilient to worms, but there could be other reasons why that sheep is a good doer,” Mr Toland said.

“For me the bottom line is that resilient sheep might cope pretty well with worms, but they are still breeding worms which will affect the weaker sheep in the flock, whereas resistant sheep won’t support worm populations.

“Because resistant sheep are not facing this additional stress on their bodies, these are sheep that are more likely to do better in dry times.”

Mr Toland runs Toland Merinos, at Violet Town, Victoria, an 800-hectare property with an average annual rainfall of 625mm. The local environment is suited to the parasitic worms Teladorsagia (small brown stomach worm) and Trichostrongylus (black scour worm).

Mr Toland has been taking worm egg counts on his 4500-head flock, which includes 1200 stud ewes, for more than 10 years, while at the same time selecting heavily for worm resistance as part of the breeding program.

“As well as selecting rams with a negative WEC ASBV, we cull heavily for animals showing scours or dag,” he said. “Breeding for resistance can take a long time, but we’ve noticed with our flock that animals with high or positive WEC scores are often the first sheep dirty with scours.”

Mr Toland said that his worm populations have declined dramatically and his reliance on drenches has been greatly reduced delivering significant savings in terms of dollars, time and labour.

“At the end of the day I want sheep that are both resistant and resilient – that is, I want sheep that don’t carry worms but can also cope with life’s stresses and strains and remain productive,” he said.

· For more information on breeding sheep for worm resistance visit www.wormboss.com.au.

<ends>

Media contact: Janelle Holzberger on 02 6773 2927″

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The media release above (used here with permission) was prepared by Michael Thompson for the Sheep CRC and edited by Assoc. Professor Dr Lewis Kahn (Executive Officer of ParaBoss) with input also from Dr Brown Besier.

The article, large parts of it at least, appeared as part of a bigger piece by livestock editor Jaimie-Lee Oldfield in The Land newspaper on 10 April 2014.

Bear in mind this is a newspaper article, not an exhaustively accurate scientific treatise on the subject. Still, it is of value for persons like myself who have short attention spans, and for others.

More information:

http://www.wormboss.com.au/tests-tools/management-tools/breeding.php

Fasciola in humans

I was looking for information on watercress (I didn’t know it was a Nasturtium) and fasciolosis in humans and came across this:

http://www.cdc.gov/parasites/fasciola/gen_info/faqs.html

‘Quite interesting really, and not too long. An excerpt: “People can protect themselves by not eating raw watercress and other water plants, especially from endemic grazing areas. “.

I know of at least one human case of fasciolosis in the New England region associated with consumption of watercress harvested from a creek on farm.

Some have suggested that ‘wild-harvested’ watercress can be rendered safe (from parasites for example) by rinsing then soaking in dilute hydrogen peroxide (http://foodfacts.mercola.com/watercress.html). This, in fact probably just thorough rinsing, may work for nematode larvae, but I have my doubts regarding the infective stages (metacercariae) of Fasciola as they encyst onto herbage.

Related: https://wormmailinthecloud.wordpress.com/2011/02/01/wormmail-20110201-trichostrongylosis-in-humans-redux/ (Yet another reason that real man eschew salad).

FWEC Course

May 21 Tamworth.

For more information, including other dates and locations:

http://www.dpi.nsw.gov.au/agriculture/profarm/courses/faecal-egg-counts

For even better information or to register call Cassie Gardiner 6763 1276 or Julie Chapman 6763 1285 or email [tamworth.profarm@dpi.nsw.gov.au].

Phone app trains you to beat jet lag › News in Science (ABC Science)

http://www.abc.net.au/science/articles/2014/04/11/3982860.htm?site=science&topic=latest

Phubbing

One view:

http://stopphubbing.com/

Phub not lest you be phubbed? 🙂

Murcott’s Easter Road Safety Message

http://tinyurl.com/murcott-road-safety ‘Worth a look (it’s only short). (Actually, in motorcycle training we are taught 3 seconds back (in the dry) and 4 seconds (in the wet))

Moron more on multitasking

http://www.dilbert.com/strips/comic/2013-11-13/

Regards,

SL

WRML. It’s April: nuke the fluke; prep for lambing

To WormMail (WRML) mailing list (recip. undisclosed). 2014-04-09

April – nuke the fluke

It’s April, so if I don’t say something about liver fluke (Fasciola hepatica) (which I would anyway, of course), I will be getting emails from ‘Professor Fluke’ (Dr J C Boray).

April or May (whenever the cold weather sets in) is the time for the most important strategic liver fluke drench in south eastern Australia.

All this assumes that you know whether you have fluke and even perhaps which paddocks are ‘flukey’ and which aren’t.

April-May marks the end of a few months build-up of fluke (on pasture and in animals) and their host snails (assuming a good season), and the beginning of colder weather where fluke may be unable to complete its life cycle (just like Haemonchus – barber’s pole worm), although the infective stages (metacercariae) may survive in declining numbers through to spring (just like Haemonchus infective larvae).

It’s important to bring out the big guns – the most effective flukicides- for the April drench. For sheep and goats and alpaca, this means triclabendazole-based drenches. In cattle there is also the added option of Nitromec(R) (clorsulon+nitroxynil (both flukicides), + ivermectin).

Another reason to drench now for fluke is that it may be needed as a tactical treatment as well: i.e. you may have stock dying, sick or subclinically affected with fluke disease.

As Rad Nielsen said in WormBoss News – March 2014 (http://www.wormboss.com.au/news/outlooks/nsw.php ):

‘Liver fluke infections in both sheep and cattle are more prevalent in the New England region this summer. Stock have been forced to graze in the normally wet areas of paddocks, ingesting liver fluke in the process. Treatment for this parasite is advised over April/May (if not already given) on those properties with known positive fluke status. If uncertain or seeking confirmation, fluke egg counts on faeces or blood antibody analysis are the common laboratory tests utilised to establish liver fluke status of livestock’.

Image below: Fluke map from ‘Seddon’, 1967*:

* Seddon HR, revised by Albiston HE, 1967. Helminth Infestations, in ‘Disease of Domestic Animals in Australia’. Commonwealth of Australia, Department of Health.

Also see map in the Primefact by JC Boray (Liver fluke disease…): http://www.dpi.nsw.gov.au/agriculture/livestock/sheep/health .

Lambing paddock prep

Those who lamb in Spring (say September) will be joining (tupping in NZ, UK) about now.

In many sheep areas of NSW, especially cooler areas (where larvae take longer to die), you need 5-6 months** to prepare lambing paddocks so they are relatively low worm risk. (** 2-6 months depending on time of year, and location/climate).

Essentially this means keeping sheep (and goats) out of the lambing paddock during preparation time, unless:

(1) it’s too cold for the important worms in your area (too cold for eggs to develop through to infective larvae)

(2) and/or the sheep are not shedding worm eggs in their faeces (recently drenched with a product you ‘absolutely know for sure’ was close to 100% effective)

As to (1), I am particularly thinking of the New England here and Haemonchus, our bogey worm, but not the only important worm. Haemonchusis a drama queen (it kills sheep; ‘not a quiet achiever like the scour worms), but it is also a delicate little princess when it comes to its eggs.

Haemonchus eggs once deposited on pasture only live 7 days or so, and in that time need temperatures generally above 10 (deg. Celsius) at night and 18 during the day, and lots of moisture (roughly 10 mm rain (or equivalent) or more every several days).

(This ‘epidemiological’ information on various worm species can be found in the Appendixes/Tables at the end of Your Program (for different regions in Australia) in WormBoss. I don’t need to remember this information anymore: I just need to know how to get to WormBoss ;-).

All this information on paddock preparation by the way is spelled out in a highly readable and digestible (and printable) format in Your Program at WormBoss.

And here is what WormBoss says for the New England for example with respect to lambing paddock preparation ( http://www.wormboss.com.au/programs/tablelands-slopes.php ):

Prepare spring lambing paddocks by preventing contamination with worm larvae in the 6 months prior to lambing:

  • March and April: spell paddocks, graze with cattle or graze with sheep only in the 0–21 days after an effective drench. (This might include part of May in very mild autumns i.e daily maxima still 18 degrees or above)
  • May–August: no grazing restrictions apply when maximum daytime temperatures are consistently below 18°C, if they are not then use the same strategy as for March and April.

And here, for example, is the good oil for non-seasonal rainfall areas of NSW (central and southern NSW) (http://www.wormboss.com.au/programs/nsw.php ) with high rainfall (eg tablelands and nearby slopes) :

  • Prepare low worm-risk paddocks for lambing and weaning by preventing contamination with worm larvae in the 2 to 5 months before they are needed. (Click here for the number of months required for your location). In this time, spell paddocks, graze with sheep only in the 0–21 days after an effective drench, or graze with cattle.

Liver fluke and ‘rotten’ country – more from the archives (Dr Hugh Gordon, 28 March 1909 – 23 April 2002 )

Dr Neil Cooper, a past Secretary for Australian Veterinarians in Industry (an Australian Veterinary Association interest group), passed on to me a letter written by Dr Hugh Gordon to the AVI on 23 May 2000

We featured some Gordon-related memorabilia in a recent WRML: https://wormmailinthecloud.wordpress.com/2014/03/20/wrml-2014-03-20-from-the-archives-mainly-re-dr-hugh-gordon-sheep-worm-control-australia-other/

Below is my attempt at transcription (at age 91, his handwriting was better than mine is now (age approx. 30-60)):

"Dear …..,

My apologies for the meeting in Perth – wish I could be there but ‘advancing years’ rather restrict by 91 years. I trust you have a successful gathering in Perth – I was last there for my 80th birthday which happened to be the opening day of the Conference – ??? fine?? party? That night ??.

What changes we have seen – my earliest introduction to parasitology was in the bush on my father’s sheep and cattle property west of Armidale – he used to show me the Barbers Pole Worm in “ration” sheep, or the nodules (Oesophagostomum – a rare species now?) which he blamed on arsenical drenching. It was my job from age? 10 on to ? “Webbers”? arsenical? Drench.

I learnt the zoological names of the worms from a booklet written by? H.A Veron Of Vita-Lick which was one of the few firms in those? days which marketed anthelmintics.

Sagers? Allport was on the job too when carbo.tet. came on the scene. “Green ? Seal?” which I think was “a guinea a gallon”. It was (a) near miracle drench then – in? the? 1920’s it converted lots of “Rotten” country into useful sheep properties as it kept Fluke down to reasonable levels. One of the great gaps in research – we still don’t know why CCL4 was sometimes deadly for host as well as parasite.

Best wishes to all at the muster in Perth and I trust you have a successful meeting.

Hugh Gordon"

I decided to check on Mr Veron.

A search yielded this from http://trove.nla.gov.au/ndp/del/article/70221268 (retrieved 2014-04-01):

Stock Expert. (1932, August 18). Albany Advertiser (WA : 1897 – 1950), p. 2. Retrieved April 1, 2014 (it’s not a joke), from http://nla.gov.au/nla.news-article70221268

“Stock Expert

MR. H. A. VERON’S VISIT.

"Severe losses of stock have been sustained in Western Australia, during the last twelve months, especially in the Eastern Wheatbelt-the sheep and cattle dying from what appears to be toxic paralysis. . ~

Stock owners will be pleased to hear that Mr. H. A- Veron, Technical Adviser to Vita-Lick Limited, is visiting Western Australia during September and October and will be giving a series of Lectures and demonstrations in various parts of the State.

It will be remembered that Mr.Veron, who visited Western Australia last year, formulated a special mineral mixture for cattle suffering from Wasting Disease in the Denmark district. The results were so spectacular that the Agricultural Bank are now supplying all stock in the Denmark district with this lick.

This year, Mr. Veron is particularly interested in the paralysis disease in the Eastern Wheatbelt. Analyses are being carried out of the pastures throughout these districts, and in all probability a special mineral supplement will be formulated with the object of preventing these losses in the Eastern Wheatbelt.

Anyone wishing to meet Mr Veron should write direct to Goldsbrough. Mort and Go. Ltd., as Mr. Veron is visiting Western. Australia under their auspices. “

I asked WA veterinarian Dr Brown Besier for his comment:

" (It is) interesting that a worm (liver fluke) prevented the use of grazing land – a bit like Haemonchus does for some tropical areas now.

The wasting disease at Denmark, also called “Coast Disease”, is copper and cobalt deficiency – a product of the light sandy soils in many parts. To this day, thin, unthrifty cattle and sheep occur where supplements are not give to schedule. Great research by the University of Western Australia agricultural faculty and Ag Dept pathologists in the 1930s elucidated this. "

Using the internet search engine of my choice, I could not find out what ‘toxic paralysis’ meant, and various newspaper articles in Trove, shed no light either. I then wandered down to a colleague’s office, and ferreted out his copy of Hungerford’s Diseases of Livestock (8th ed., 1975), wherein I found, on page 248, that toxic paralysis was, perhaps still is, another name for botulism. (So much for the internet).

So, it may well be that the vaccine being trialed in Western Australia (mentioned here: http://trove.nla.gov.au/ndp/del/article/38942366 – Western Mail – Perth – 1935), was an anti-botulinum vaccine. Preventing pica (e.g. chewing bones) by way of nutritional supplementation of course is also a preventive measure (which perhaps is where Mr Veron and others came in).

Here is a WA factsheet on botulism (https://www.agric.wa.gov.au/livestock-biosecurity/botulism-cattle), one of the authors being Brown Besier’s son.

The voice of Siri – an Australian

http://www.abc.net.au/radionational/programs/360/meet-the-voice-of-apples-siri-karen-jacobsen/5367820

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