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Treatment Strategies to control Parasitic Roundworms In Cattle

Dave Bartley

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Which roundworms are most likely to cause problems?

Scientific name Common name Disease

Ostertagia ostertagi Brown stomach worm Type I & II

Cooperia oncophora “No common name” -

Dictyocaulus viviparus Lung worm Husk, hoose

Haemonchus contortus Barber’s pole worm Haemonchosis

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The need for control

• Health and welfare

• Effects on food quality

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Loss of gut integrity leading to loss of proteins and

minerals

Increased turnover and

replacement of damaged

cells/tissue

Decreased production of:

Muscle

Skeleton

Milk

Fertility

Decreased nutrient absorption

Tissue damage

Protein diverted from productive tissues to repair damage

Impaired gut function

Reduced feed intake and conversion

Effects of gastro-intestinal parasitism

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The need for control

• Health and welfare

• Effects on food quality

• Reduced profitability

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Age group Production effect

First Season grazing (FSG) calves

• Reduced growth rate

Second season grazing (SSG)

• Reduced growth rate • Delay in puberty & reduced conception rates in replacement heifers • Reduced in-calf rate in heifers • Loss of carcass yield and quality

Dairy cows • Decreased milk yield • Longer calving to conception interval • Decreased in-calf rates

Beef cows

• Decreased milk yield • Longer calving to conception interval • Lower weaning weight of their calves • Decreased in-calf rates

Adapted from – Forbes PhD Thesis 2008

Production losses associated with PGE?

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How to tell if worms are causing the problem?

• Clinical signs, season

• Grazing history

• FEC (not Type 2 Ostertagiosis)

• Plasma pepsinogen (Ostertagiosis)

– animals < 2 yr

• Pasture larval (L3) counts

Mar Apr May Jun Jul Aug Sep Oct

L3

Eggs

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Worm control strategies

IMMUNOLOGICAL

Vaccines

Genetic selection

Optimised nutrition

MANAGEMENTAL

Grazing management

Biological control

Organic farming

CHEMICAL

Anthelmintics

Bioactive forages

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Strategies - considerations

• Exposure times

– Parasite species

– Parasite exposure levels

• Management strategies

Factors

Enterprise type Beef Dairy

Age Adult Calf

Exposure FSG SSG

Birth date Spring born Autumn born

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Anthelmintics

Anthelmintic class

BZ (I) LEV (II) ML (III)

Pour on - -

Injectable -

Drench -

Bolus - -

In feed mix - -

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Anthelmintic class used in preceding 12 months

III only

I + III

I only

II only

ML only ML + BZ BZ only LEV only

Pour-on (n=69)

Bolus (n=28)

Injectable (n=22)

Drench (n=21)

Pour-on Bolus Injectable Oral drench

Anthelmintic application methods

Anthelmintic usage pattern

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Some questions to consider – Was the correct dosage given?

Was the drench administered correctly?

Had the anthelmintic been stored correctly?

Was the correct formulation used for your host species?

Is the treatment effective against the target species? ……….

Is anthelmintic resistance a problem?

Do treatments always work, if not why not?

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Anthelmintic resistance

• When worm populations survive a correctly-applied, standard dose of anthelmintic

• GENETIC - resistant worms produce resistant offspring

• A PRE-ADAPTIVE phenomenon – genes that confer resistant already present in population

• IRREVERSIBLE – no effective return to susceptibility even after removal of selecting anthelmintic

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Country BZ LEV ML Country BZ LEV ML

Australia + - - Germany - - +

Argentina + - + Mexico - - +

Bangladesh + - - New Zealand + + +

Belgium - - + Sweden - - +

Brazil + + + UK - - +

Chile - - + USA + + +

Anthelmintic resistance in cattle

AR to MLs reported worldwide, little known in UK but previous reports of inefficacy of ML vs Cooperia spp.

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ML inefficacy in UK

Farm

• Faecal egg count reduction test

• 50% IVM sensitive

• 39% IVM efficacy 50-95%

• 11% <50%

• Two isolates further investigated both IVM and MOX resistant

• Suppression in egg development and oviposition

• ML resistant Cooperia species – SO WHAT?!

McArthur unpublished data

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Recent studies • NZ study - IVM and ABZ

resistance on 74% farms where Cooperia spp present

• Resistance of Ostertagia spp to IVM evident (9% of farms), ABZ (35% of farms), LEV (9% of farms)

• Possibility resistant Cooperia are more pathogenic than susceptible ones

• Can cause production loss up to 12kg weight loss over grazing season

Wikipedia

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Sustainable control

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Pasture management - Risk factors

Factor

Risk Low Medium High

Age/exposure >2 years/adult 1-2 years/SSG <1 year/FSG

Herbage mass kg DM/ha

>2000 1000-2000 <1000

Sward height >8 cm 4-8 cm <4 cm

Pasture type Newly sown, “clean grazing

Silage/hay aftermath

Permanent pasture

Previous grazing history (< 12 months)

Grazed by adult cows, sheep** or other species

Grazed by cattle 1-2 years old

Grazed by cattle <1 year old

Adapted from – AHI parasite control leaflet 2012

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Rotation grazing

• In short term rotational grazing has been shown to reduce need for treatment frequency BUT may lead to

• Changes in species composition on pasture, such as increase in Cooperia species, Trichostrongylus axei

• Parasites developing ability to infect non traditional hosts e.g. Ostertagia ostertagi in sheep

• Changes in life history traits delayed/increased development times from eggs to L3

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Targeted treatments

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TT – What information is needed

Over time monitoring can provide the necessary information e.g. What parasites are present during the season

The extent of challenge and risk of disease

Which anthelmintics are working on the farm

This information should guide the development of farm specific worming programmes

Targeted treatments (TT) are those where the entire group (whole flock or mob) of animals is treated

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Treatment/Monitoring timings

Enterprise Calving Areas to think about

Beef Spring • Adults relatively refractory to worms BUT generate huge quantities of faeces – add to pasture contamination • Pre-wean consume mostly milk lower L3 intake • Monitoring in autumn advised • May delay development of immunity and be prone to type II ostertagiasis

Autumn • Mostly housed early • Turned out after winter, see pasture/L3 following year • Grass intake early L3 intake early • Early monitoring advised

Dairy Spring • May go to pasture early following milk substitute & concentrates exposed to L3 early • Early monitoring advised

Autumn • See pasture following year • Grass intake early L3 intake early • Early monitoring advised

No one size fits all /blue print advice available

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TT – Examples

O. ostertagia ELISA applied on bulk tank milk at end of grazing season Measure of exposure of the herd to GI nematodes, high values (> 0.8 ODR). 53 % of UK herds ≥ 0.8 ODR (UK study; Forbes et al., 2008 ) Serum pepsinogen concentration indicator of abomasal damage caused by O. ostertagi - correlated with weight gains Charlier et al., 2010

Live weight gain – trial in Sweden Prelim results promising

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What can be done to better target treatments?

• Speak to your vet or health advisor

• Are treatments necessary? Reduce treatment frequency if possible – Adult cattle, calves at turn out …..

• Non-chemical as well as chemical control

• Use correct dose + optimum drenching technique – – (avoiding under-dosing)

• Monitor wormer effectiveness

• Quarantine treat to avoid bringing in resistant worms

• Monitor in order to target treatments effectively

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Where now?

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Dispensing anthelmintics

• Seller must give up-to-date knowledge in an understandable format

• Epidemiology/farming practices

• Anthelmintic sensitivity/resistance

• Sustainable control = better knowledge exchange

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Acknowledgements

• Claire McArthur, Fiona Kenyon and Jacqui Matthews at Moredun for supplying information

• Norbrook Laboratories Ltd and AHDA for invitation to present