Integrated parasite management

what is integrated parasite management?

multiple approaches for control are utilised, taking into consideration economic factors, epidemiology, resistance, production system, management structure

3 categories of integrated parasite management

- indentify risk - temporal and geographical

- treating appropriately - right animals right time, targeted

- avoiding resistance - maintaining refugia parasite population (pop of parasite when treatment is given that isnt exposed to that anthelminitc → no selection pressure)

which kinds of infections allow immunity to develop over time?

trickle/ low infection challenge

which kinds of infection cause (sub)clinical disease?

high - abrupt infections

short period of time

exceeds "threshold"

= causes disease

what happens when animals face no infection challenge?

animals are naive and susceptible to infection

what is a worming control programme for?

reducing worm burden

which endoparasites do animals not develop immunity for ?

- fluke - sheep and cattle

- haemonchus - sheep

- lungworm - immunity = very short-lived

why is it important to know which parasites dont get immunity for

as it is the basis on which we develop sustainable risk-based parasite management protocols

when may animals develop immunity to endoparasites?

after first grazing season - some take multiple

How do you assess environment risk?

- grazing history

- temperature

- rainfall

rainfall risk

moisture is required for larvae to migrate away from faeces

temp risk

infective stages rely on stored energy to survive

cool and dry weather prolongs survival as movement reduces

grazing history risk

when did that species las graze pasture

were there likely to be shedding eggs

is PGE seasonal ?

YES

NOS (not otherwise specified) - summer- autumn

Haemonchus - summer

Nematodirus - spring

what do you take into account when assessing animal risk of parasites?

- grazing history - immunity generated?

- health and immune status

- FEC - treat threshold 200epg cattle, 350-400 epg sheep

- DLWG - 0.7kg/day cattle 0.3 kg/day sheep → this will dcrs before fec inrs

What is the aim of controlling PGE?

- productivity/ profitability - growth, yield, fertility

- good immunity - rather than relying on treatment

- sustainability

sustainability with anthelminitcs

Continued efficacy of anthelmintics - delay the development of resistance to the products within the parasite population.

Minimise negative impacts on the environment.

What different methods of parasite control are available? (not anthelmintics)

- integrate control measures and anthelmentics

- holistic approach

- TST - targetted selective treatment

- maximise refugia - risk based treatment, dose, delay move

resistance in anthelmintic "colours" and what species

• group 1= white → high res

• group2= yellow → incrs res

• group 3 = clear→ some res

• group 4= orange→ starting res

• group 5 = purple→ v little res

  

what are the broad spectrum wormers for cattle and sheep?

sheep - 1-5

cattle 1-3

what are group 1 wormers?

benzimidazoles

white drench

cattle and sheep

lots of resistance

first choice nematodirus

what are group 2 wormers?

LV - levamisole

yellow drench

cattle and sheep

what are group 3 wormers?

ML - macrocytic lactones

clear

cattle and sheep

some resistance - more in cattle

What are group 4 wormers?

AD - Amino-Acetonitrile Derivative - zolvix, monepantel

orange -

Sheep only

limited resistance

what are group 5 wormers?

SI - - startect

dual active - ML (abamectin and spiroindole

purple

main use is the prolong the life of the other groups → eg use in quarantine protocol, end of grazing system→ removes resistant pops

available narrow spectrum wormers

- closantel, nitroxynil - fluke and haemonchus

- oxyclozanide - fluke only

supportive treatment for endoparasite burden

NSAIDs, fluids

How to reduce anthelmintic resistance risk when you have to treat?

- treat selected animals if possible

- use narrow spec if possible

- ensure you give the correct dose - can dose for heaviest animal or weigh each - calibrate equipment

- quarantine purchased stock

- dilute out any AR worms - in refugia pop

- use non-chemical means of control - clean grazing

what drives resistance?

- buying in resistant worms

- underdosing

- over treating pop

- allwoing resistant worms to dominate

what is drench testing?

- post dosing faecal egg counts

- fec 7-14 days post treatment

• . 7d for LV, 14d for ML or BZ

- indicates anthelmintic efficacy

- can do pre-dosing FEC→ see reduction in fec

what is FECRT ?

faecal egg count reduction test

- individual samples pre and post drenching

- choose lambs with high FEC >500epg

- split into different groups and worm with different classes

- resample 7-14 days

less than 95% reduction = resistance

less than 50% = drench failure

how can anthelmintics affect the environment?

- impact no-target invertebrates - dung beetles, earthworms

- soil health - poorer forage/ crop growth - ecosystem damage

- leach into water courses - aquatic life

what is the optimum threshold

• between animals that benefit from treatment but not treating those that wouldnt

  

how can we try and get into the optimum threshold by minimising treatments

Using targeted selective treatment (TST)

Maintaining a ‘refugia’ population of parasites

Combining chemical and non-chemical parasite management

How do you use targeted selective treatment?

when?

• pooled FEC - every 3-4 wks to track rise and predict when treatment is required

Who?

• targeted selected treatment - using DLWG, poor growth and feed conversion efficacy >350/4000epg

fec result thresholds

Poor growth and feed conversion efficiency with a FEC >350/4000epg (in cattle around 200epg may be used as tx threshold)

Obvious Clinical disease >500 epg

Deaths >900 epg

what to do if fec results are borderline

borderline→ think abt the weather for last 3wks→ middle of summer l1-l3 can take few weeks → dry and hot = unlikely much contam → bc l3 stuck in faeces and metabolising at high rate

• but mild and wet → lots around that can migrate and infect

when are the results of fec from

results are from the ingested larvae about 3 weeks ago

ppp- 21d

if youre not sure what is going on within a herd/ flock with parasites what percentage should you leave untreated

10%

what kind of scoring can also be used to assess haemonchus burden?

FAMACHA

- can be speciated by APHA also

- very fecund - lots of eggs, not scouring

what is dlwg

Daily Live Weight Gain (DLWG) = growth rate.

DLWG is high pre-weaning because milk is so nutritious, it then slows down as the lamb/calf matures and is eating grass

expected DLWG changes

Expect >300 g/d

• Pre-weaning lambs

200-300 g/d post weaning until the winter.

150 g/d over autumn/winter

In cattle 0.7kg/d has been used (but will vary between farms)

Are parasites usually spread through a flock ?

abt 80% of the worms in 20% of animals - badly effected

esp lambs

• so if can treat these 20% it is better, and leave the 80%

  • can use dlwg to target this

what is the happy factor

‘Happy Factor’ used to predict weight gain targets – only treat lambs failing to meet these

what is in refugia pop

Maintain an in-refugia population that is not exposed to treatment (free-living on pasture and adults/immature in untreated sheep), this will dilute the eggs produced by AR worms. Whole flock or whole group treatments to be discouraged.

why should we maintain in-refugia population?

dilutes the population of eggs producted by anthelmintic resistant worms - diversifying population, so they don't dominate

- treat part of the flock

- delay moving them - pasture has non-resistant

what kinds of pasture and pasture history are associated with different levels of risk when treating the whole flock

• if treat whole group → put on low contam pasture → only parasites that we will have are the resistent ones→ lay resistant eggs → pop of parasites on pasture that are resistant to the anthelmintic

• worm whole flock → onto high contam pasture→ shed resistant eggs → mixed pop of parasites → but is a big pop → sheep need treating again → less resistance but still not ideal

  

what is the resistance like in a flock with tst and dose delay movement

• part flock treatment → low contam flock → some res some susceptible → small parasite pop but quite a bit still resistent

• treat part of flock and delay movement (keep on dirty pasture) → reinfect with susceptible parasite → new clean pasture → mixed pop but with few resistent parasites

  

how can we maximise in refugia pop

• only treat some of the animals AND delay movement

  • maximise anthelmintic efficacy whilst minimising negative impacts on production due to parasites

how can we assess pasture risk

Grazing management with weaning animals

move lambs to low-risk grazing → usually post silage cut

pasture/ less contaminated areas

grazing management - co-grazing

reduces stocking density of host species

grazing management - nutrition

minimoses adverse effects of parasitism

grazing by cattle/ mature ewes to take up larvae first

grazing management - rotational grazing

calves/ lambs stay on pasture <3w and are followed by mature animals

grazing management - delayed turnout

pasture contamination lower later in summer - used up energy/ died

not always practical/ might not have space

what is EBV?

estimated breeding values → breed specific (mainly in sheep)

measure of breeding potential of an animal for a specific trait.

• performance data of animal - expressed relative to baseline for the breed

• takes intp account performance of relatives and heritability of the trait

using rambs selected for worms resistance can be useful for flocks breeding ewe replacements

measure FEC, IgA

what is desirable for EBV

- low FEC and high IgA is desirable

Biological control of endoparasites

bioactive forage

- chicory, birdsfoot, trefoil, sainfoin

do they have direct anthelmintic properties or improve nutritional status

biological control- monitor dung beetles, earth worms, fungi → disperse l3

how do you make a plan for endoparasite control on farm?

take detailed history of management practice→ bc farm specific

identify threats and when stock are at risk

what options you have for monitoring and control

How do you assess threats to parasite control?

list parasites

• rank them - priority and chronology

risks through year

• parasite risk

• grazing risk - intermediate hosts

system and non-chemical control

what is appropriate for nematodirus

FEC’s not useful but strategic prophylactic treatment with a BZ based on the timing of the larvae peak is appropriate

what is appropriate for trichostrongyles and telodosagia

Regular, routine FEC and DLWG monitoring and treatment only at a threshold epg is the most effective method (TST) to prevent disease and minimise resistance.

what is appropriate for liver fluke

Monitor for exposure and avoid high risk pasture at high risk time.