An integrated approach to parasite management looking at muck testing and alternative grazing techniques could lead to savings in labour and money.
On the face of it, current youngstock parasite control methods may seem routine, cheap, easy to administer and have worked for decades.
However, vet Rob Howe and his colleagues at LLM Farm Vets have been working with farmers on a pilot project, to see how muck testing and alternative grazing techniques can reduce and often eliminate the need for wormers to control lungworm, gut worms and fluke.
Mr Hoye says: “We are aiming to improve animal health, minimise resistance to multiple pour-on treatments and boost soil and ecosystem health, leading to further productivity improvements, while saving farmers time and money.”
A starting point when trying an integrated approach to parasite management is to reduce or remove unnecessary treatments.
Mr Howe says: “This can be done by regularly muck testing while cows are turned out. Farmers, vets or vet techs can collect the samples, ideally from three sites within 15 fresh pats, and then deliver the samples for testing.”
Mr Howe explains that animal age, immunity status and history of the pasture will affect how often tests are needed. He recommends every four weeks as a starting point, using treatments when egg counts and other signs suggest burdens are becoming a problem.
“By looking at the numbers of worm eggs, and in the case of lung worms, hatched worms, it is possible to understand the level of exposure to parasites.
“This is used alongside other observations such as growth rates and how the animals look and behave, to determine whether wormers are needed.
“This year we discovered that approximately 40 per cent of our herds did not need to use a wormer over the entire 2020 grazing season, which saved our farm clients significant labour and product costs, running in excess of £1,000 in some cases.”
Mr Howe explains that muck testing and only treating when needed can have a real impact on preventing parasites becoming resistant to the treatments used to control them.
He says: “The most common method of control, which is currently used on approximately 50 per cent of farms, is multiple pour-on treatments of persistently acting macrocyclic lactones (MLs), such as ivermectin.
“When parasite populations are exposed to repeated and persistent treatments within a grazing season, this represents an enormous selection pressure, meaning the parasites left after treatment are those which can resist it, and are also those which manage to reproduce, passing the resistance on to their offspring.
“It is also very common for the same protocol, whatever it may be, to have been used for over a decade, which increases the threat of resistance.”
Mr Howe highlights that set stocking youngstock on the same ground each year, often close to the farmyard, is common as it makes sense from a labour and management perspective.
He says: “However, the downside is that year-on-year, the riskiest stock contaminate the same ground, and relies on wormers we are already seeing resistance to. Any variation to this set stocking, such as using a different field, can break the parasite lifecycle.”
Enabling youngstock to develop immunity to parasites they will be exposed to later in life, by not over-applying treatments, can also have real benefits.
Mr Howe explains that strategies rely on youngstock achieving sufficient time of effective contact with parasites to allow an appropriate level of immunity to develop.
Bruce Thompson, a commercial dairy farmer, uses a ‘traffic light’ system to graze youngstock in a controlled way, minimising risk of over-exposure to gut worms.
He says: “We use muck sampling to assess the burden of parasites placed on each paddock as each grazing or harvesting event is concluded.
“Mapping this risk around the farm allows us to allocate grass to the most suitable animals based on their vulnerability and the risk of pasture, using a red/amber/green system.
“For example, a field may be labelled ‘red’ in autumn following a high FEC recorded in a group at housing. Over winter many worms die off, so by spring this would be labelled ‘amber’. It could become ‘green’ if immune adults were then used to ‘hoover’ up infective worms.
“The system has allowed natural ecology to help reduce parasites including ostertagia and fluke, both now testing low on bulk tank monitoring.”
Mob grazing can also play a role in parasite management. It is an adaptive management practice which mimics the natural pattern of wild bison or wildebeest migrating and grazing grasslands where parasites do not cause problems.
Mr Howe explains: “It is effective with grazing animals in the UK because the rest period is far longer (30-90 days) than a traditional rotational grazing system, breaking parasite life cycles very effectively.
“The grazed vegetation is also much longer, and no insecticidal worming treatments mean that dung and parasitic worms are removed by dung beetles, with any remaining parasitic worms likely to have died off, been diluted or be far from the tips of grazing being foraged.”
For Mr Howe, dung beetles are the unsung heroes in parasite management.
Research from 2015 demonstrated they are worth £367 million to the UK cattle industry alone. Mr Howe says: “Dung beetles remove dung and the parasites within it by eating and burying it.
“They also fly between pats and are used as a free ride by mites who eat the eggs and larvae of nuisance flies, thus keeping numbers of flies down as well as nematodes.
“They also have numerous additional benefits such as increasing soil organic matter, improving water quality and increasing pasture fertility.”
Mr Howe explains that some parasite treatments, such as pour-on MLs and SPs (synthetic pyrethroids) can kill dung beetles, or reduce their ability to reproduce.
“MLs may be easy to use and relatively inexpensive, but their use is costing far more than many realise in terms of soil health,” he says.
“Whole sections of the soil food web can be wiped out, which negatively impacts on soil quality and ultimately animal health and grassland productivity.
“It is important these products are reserved for when we really need them, and ideally not used prophylactically.
“The work we have been doing has highlighted the potential for how different approaches to parasite control can work with essential wildlife like dung beetles, enabling improvements to both livestock and soil health.”