Strategic worming can protect pig profits

Pig producers should think about reviewing their approach to roundworm treatment this summer to improve profitability. Here, Elanco vet Alvaro Hidalgo proposes a strategic rather than sporadic management programme

Pig rearing traditionally runs on tight margins, and with 70% of farms already suffering from roundworm (Ascaris suum) infection, and infections costing up to an estimated £9.06/pig, that’s potentially very bad news for producers. Thankfully, effective cleaning and disinfection protocols, treatment with an effective anthelmintic and improved management can help control the problem.
Liver milk spot lesions are a red-flag issue. They provide a clue to roundworm infestation since they’re caused by larvae of large roundworm migrating through the liver as part of their lifecycle. However, milk spot liver points to pigs being challenged four weeks before slaughter; earlier infestations could have occurred, but the liver’s ability to regenerate means that earlier worm challenges are not detectable at the abattoir. As a result, livers would appear normal during inspection, but pigs could still be suffering from roundworm.
As roundworm initially establishes, there may be few signs that a producer can identify. Only as worm burdens get heavier and signs are seen at slaughter does it become clear that there’s a problem. By that time the pasture or housing may be contaminated with infective worm eggs that can survive for many years and are resistant to most disinfectants.
Allowing roundworm to gain a foothold on a pig unit can prove to be very expensive. Producers can expect to see up to a 10% increase in feed conversion ratios and reduced average daily gain. In addition to these significant losses, carcase and meat quality also declines and then there’s the possibility of rejection of livers. Affected pigs also have a reduced response to vaccination, leaving them more vulnerable to infection.

Vet’s view
Richard Pearson of the George Vet Group in Wiltshire says his practice is accustomed to dealing with the negative consequences of roundworm.
“We put a lot of work into helping our clients develop strategic deworming programmes that can be applied throughout the production cycle,” he notes. “Warmer weather can escalate the problem as the parasite life cycle is completed in a shorter time, so we have to be on top of the situation in the summer months.”
Richard says that experience has shown him that once roundworm becomes established there are distinct cost implications involved to re-establish control.
“We’re often talking about high-welfare, outdoor-reared herds, so hygiene and pasture rotation programmes need to be rolled out over a large area to break the parasite lifecycle,” he says.
“Once pastures are contaminated and there’s nowhere else to move pigs to, a producer can be in for a hard time. Equally, significant worm problems can build up on indoor units.”
According to Richard, an integrated approach to parasite control is important. “Gilts brought onto farm could be carrying significant worm burdens, so biosecurity is also an issue,” he says. “Parasite control should be considered as part of the unit’s isolation/integration programme. The appearance of milk spots means the pigs have been infected within the past few weeks and this should trigger an evaluation of the current control measures such as pig movements, biosecurity controls, cleaning and disinfection protocols, together with worming strategies.”
Richard’s recommendation is to take a risk-based approach to worming. “After evaluating the situation, it may be necessary to start a deworming programme that treats pigs every five to six weeks, as that’s the length of time of the life-cycle of roundworm,” he says. “The key is to hit the parasite hard before it can complete its lifecycle, minimising the risk of contaminating the environment with more parasite eggs. Put a halt to further development in that time and control will start to be re-established.”
He warns against taking a short-term view. “Don’t fall into the trap of believing that instituting a deworming programme will immediately stop milk spot problems; it’ll help, but if pigs remain in contaminated buildings, or on contaminated ground, milk spot may still be seen for quite some time. Control of roundworm requires long-term planning and long-term commitment.”

Action plan
A strategic deworming programme using flubendazole (Flubenol 5% w/w Premix for Medicated Feeding Stuff) for five days every five weeks for all grower/finisher pigs has been shown to be effective at controlling roundworm and reducing milk spots. The breeding herd can also be a significant source of pasture contamination and it’s a false economy to fail to treat these animals.
Taking a strategic approach to worming can ensure that profits are protected and that animals reach their full potential. Producers are encouraged to work with their vet to develop a strategic deworming programme that reflects on-farm challenge, in the light of evidence from diagnosis, stocking density, performance against production targets and information about rejected livers at slaughter.
While the five days every five weeks routine used in feed for all growers/finishers is a good guideline when using flubendazole for controlling ascarids, other harmful worms such as the damaging whipworm (Trichuris suis) may require more intensive treatment and your vet is best placed here to advise.
Due to the complex lifecycle of the roundworm, it’s important to ensure that any anthelmintic in use has demonstrated efficacy against mature and immature stages of the parasite. In contrast to ivermectins, that are only active against last larval stage and adults, flubendazole acts against earlier larval stages that cause milk spot liver damage.
Selection of a product that’s active against other parasitic worms might be critical in some units. A major pig worm threat such as whipworm can cause serious damage to growers resulting in bloody diarrhoea and even mortality, and while flubendazole is active against this parasite, ivermectins aren’t.
The practicality of dosing regimes should also be considered. Feed delivery intervals may determine when in-feed wormers can be used, so it’s important to ensure that the product chosen can be given using a flexible dosing programme.
While spring and autumn treatments have become the established norm in the industry, it’s clear we could do better. A more regular and strategic programme of treatment could improve the health and welfare of the herd, and ultimately enhance profitability.

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