The aim of integrated parasite management (IPM) is to reduce the use of and reliance on parasiticides to control disease. IPM is achieved by incorporating complementary measures that can help reduce the populations and impact of pathogenic species, such as roundworm, lungworm and liver fluke.
The Control of Worms Sustainably (COWS) group bases its advice on the responsible use of anthelmintics, with the aim of ensuring that products are only administered when necessary. Ideally, this means only when a case is supported by a diagnosis or risk assessment that confirms the need to protect animals from a genuine risk of disease.
There is also increasing interest in the biodiversity benefits of grazing livestock, including the merits of incorporating IPM methods into husbandry practices. However, many compounds used to treat or control parasites in grazing ruminants have the potential to negatively impact invertebrates, such as dung beetles – the value of which has been estimated at £367 million per year (NE, 2016). The negative effect on dung beetles has a knock-on effect on wider biodiversity. This can occur when the active ingredients or their metabolites are excreted in the manure and/or urine of treated animals or leach into the environment because of poor storage, application or disposal.
Integrated parasite management tools
Most of the current control strategies against roundworm, liver fluke (Figure 1) and lungworm (Figure 2) rely on using cheap wormers that are applied to entire groups of animals at pre-determined times of the year. On many farms, the same products have been used at the same time of the year for more than a decade.
The IPM toolbox has many elements and differs according to which parasite is causing the problem. Ultimately, the toolbox includes testing before treating, vaccinating only on farms with a known problem (such as lungworm) and carefully planned pasture management. All these elements should be considered in a herd health plan.
This approach aims to facilitate the development of cattle immunity, allowing beneficial organisms to help control worms and pest species and reduce farmers’ reliance on products, instead saving them for when they are really needed.
Integrated parasite management in action – a case study
Over the past four years, vet Rob Howe, a member of the COWS group, the British Cattle Veterinary Association (BCVA) and VetSustain, has worked with 30 dairy farm clients in Lancashire, helping them practise IPM. He took learnings from farmers, scientists, parasitologists and others to carefully implement what COWS believes is the first such commercial trial of IPM in the UK, going against the then predominant approach of blanket parasiticide application.
Rob’s results show savings in wormer cost, time and stress from repeated cattle handling while reducing the chances of parasite resistance and having better environmental outcomes. (The VetPartners group has supported Rob to begin to document and publish this as clinical research, but until publication, his thoughts on this are his experienced clinical opinion.)
To start, Rob sat down with all the farmers to find out how each had been using wormers historically. In most cases, testing was not carried out to determine if, or at what level, parasites were present before treatments were given. He advocates this as an essential starting point to understand the whole farm context. Although youngstock (Figure 3) suffering from excessive gut worms will suffer and lose weight, there should be early warning signs that can be detected.
The Lancashire farmers were then encouraged to monitor stock closely, and gut worm levels were measured regularly, using the VetTech team at LLM Vets to collect dung samples for worm egg counts (WECs). The aim was to only treat if the faecal egg count (FEC) results combined with evidence of how the stock was performing indicated this was necessary. This often meant deciding when FEC results were on an upward trajectory.
What questions should I ask when considering integrated parasite management?
Targeted treatment – which animals should I treat?
Any decision to treat a herd with parasiticides should trigger the question: “Which animals should I treat?” In most cases, some individuals can be left untreated as a minority of animals produce the majority of worm eggs. The farmer and vet should come to a decision on the percentage of individuals to treat and leave on a case-by-case basis. It should be a risk-based decision and should be monitored after treatment with repeated FECs.
Treating only a select percentage of individuals leaves a proportion of the parasites untreated, maintaining refugia populations unexposed to treatments. This allows for the repopulation of pastures with susceptible worms in the expectation that they will dilute any resistant populations left in treated animals. It also provides dung to pasture without insecticides, allowing beneficial fauna, such as dung beetles, to feed and breed successfully.
Is liver fluke present?
The presence of liver fluke usually requires whole-group treatment in the absence of individual testing. However, taking pooled blood samples from groups of first-season grazing animals around housing to test for liver fluke antibodies is a way to determine whether the parasite has been present over the season. Fully clear results may indicate that blanket treatment can be avoided.
Taking pooled blood samples from groups of first-season grazing animals around housing to test for liver fluke antibodies is a way to determine whether the parasite has been present over the season
Copro-antigen and fluke egg count tests can also be considered, particularly to monitor untreated groups through winter. Other options, such as bulk milk tests, can also be used to inform of herd-level exposure and to see whether further treatment or diagnosis is needed. A pen-side lateral flow test for the detection of fluke antibodies in individual animals should be commercially available later this year. This new test will open new opportunities for those who want to treat their cattle individually or make group-based decisions in real time.
Can I predict the presence of lungworm?
There is no easy way to predict easily if or when lungworm will hit, and waiting for coughing to start is often too late. For this reason, particularly on farms with a history of outbreaks, Rob advocates vaccinating young calves before they go out to graze for the first time.
The switch from macrocyclic lactone (ML) treatments to vaccination has resulted in anecdotal but significant health and production benefits in some Lancashire case studies. However, this is possibly due to undetected resistance or better control rather than timed dosing. This is hard to prove, but a recent COWS workshop held at Moredun focused on this: researchers are now asking vets to report suspected cases of resistance they come across this year via a survey for investigation.
Trials carried out by Dr Bryony Sands, working with 29 dairy farmers in the USA, showed that the way cattle grazing is managed can help in the fight against parasites (Sands et al., 2024). Rotational grazing strategies effectively controlled internal parasites (Figure 4A). Faecal egg counts taken on farms grazing this way were comparable to farms where chemical wormers were being used, and the higher the number of dung beetles, the lower the number of pest flies present (Figure 4B). Similarly, cattle had reduced gastrointestinal eggs in their faeces when there were more dung beetles around (Figure 4C).
Testing, training and policies for integrated parasite management
Testing is the cornerstone of IPM; the easier, faster and more efficient it is the better, as it facilitates widespread testing. However, there is also a need for more training and education on parasitology for qualified and trainee vets and technicians.
Previous IPM-related workshops at BCVA conferences have been “standing room only”, but there is a clear demand for more learning opportunities for vets. Mark Pass, SQP/RAMA, a member of COWS, came to this conclusion after interviewing vets, SQPs and dairy farmers about their approach to lungworm treatments (Pass, 2022). His research showed that dairy farmers receive most of their lungworm advice from SQPs (69 percent), with much less involvement from their vet (31 percent). The fact that SQPs cannot prescribe lungworm vaccinations and vets rarely prescribe anthelmintics is, therefore, part of the problem. There needs to be more training and CPD for everyone involved in deciding whether to treat and what to treat with.
These sentiments are reflected in the British Cattle Veterinary Association’s Policy Statement on Parasiticides, first published in 2021 and updated in 2022 (BCVA, 2022). BCVA says it is committed to developing a greater understanding of the complexities of parasitology in the veterinary profession and states that it is essential for farm vets to have the resources and relevant understanding to raise awareness of anthelmintic resistance in cattle. The statement also recognises that the profession must have the ability to create strategies with their farm clients to reduce unnecessary use of these products and to be able to demonstrate that the use of these products should be targeted and structured, based primarily on scientific evidence.
The profession must have the ability to create strategies with their farm clients to reduce unnecessary use of these products [parasiticides]
Last year, COWS updated all its core guides to parasite control in cattle, reflecting the shift towards IPM, with more on testing before treating and putting plans in place that consider the wider impacts of treatment. These can be found on the COWS website.
The Dung Beetle Conference
On Tuesday 11 and Wednesday 12 June 2024, Yeo Valley Organic is hosting a conference at Holt Farm, Blagdon, to discuss dung beetles and their role in integrated parasite management.
The conference programme, co-sponsored by First Milk and Yeo Valley, will appeal to vets, ecologists, entomologists, farmers, SQPs/RAMAs and other animal health advisers, and all those involved in veterinary medicine policy. Integrated parasite management will be at the centre of the relaunch of this dung fauna conference, shining a spotlight on newly proven and effective approaches to reducing reliance on parasiticides.
Find out more and book your tickets here.
