Spring and summer 2024 have been difficult from a farm management and grass growing point of view, and farmers have been reporting that store and weanling cattle are between 15kg and 30kg behind their normal liveweight for the time of the year.

A shortage of grass is the compounding issue here, but the snowball effect of this was that rotation lengths were shorter, with cattle coming back into paddocks quickly and grazing them out tight. The result was a greater worm burden being placed on youngstock.

While the southern and eastern quarters of the country have witnessed dry weather pretty much since May, the remaining half of the country (north and west) saw heavy rainfall and sodden paddocks, ideal conditions for liver fluke to flourish, which it has done.

To try and minimise (and possibly regain), this lost weight gain in cattle heading into the shed, parasitic burdens need to be strictly controlled to give animals the best chance of thriving on.

Stomach worms

Faecal egg counts (FEC) should be carried out on animals prior to housing to ascertain the level of worm burden on animals. Where dosing is carried out (based off the results), then a follow-up FEC should be completed to ensure that resistance to the dose used is not present on the farm.

Caution also needs to be exercised regarding the dosage used, in that it must cover all stages of larvae of worms. If the dose administered does not cover all stages, then a follow-up dose a number of weeks later will be required, as per your vet’s advice.

Failure to properly treat all stages of stomach worms will result in type II ostertagiosis in the spring, causing severe disease in yearling animals.

Yellow drenches, derived from the active ingredient levamisole, are not effective in treating the associated larvae, whereas clear drenches (macrocyclic lactone) and certain white drenches (benzimidazoles) will provide effective treatment.

Lungworm

High incidences of lungworm have been reported, particularly on farms along the western seaboard.

It is easily identified by a husky, deep cough as animals attempt to cough up the associated worms.

Damage can be done to the lungs of animals, leaving them prone to respiratory diseases (pneumonia), so clearing up any lungworm (hoose) prior to housing should be a priority.

As regards treatment and control, most available anthelminthics are effective against larval and adult lungworm.

Levamisole and white drenches will take out the parasites present on the day of treatment, but will have no residual affect. Macrocyclic lactones, such as Ivermectins, will give longer protection.

Liver fluke

As mentioned, wetter conditions in some parts of the country have placed a greater risk of liver fluke on all ages of cattle.

Farms that have a history of liver fluke should routinely dose for such at the latter end of the grazing season with a follow-up dose when animals are turned indoors.

Liver fluke has three distinct cycles from when it enters an animal. It takes approximately 12 weeks for the fluke larvae to grow to adult stage, when they start to lay eggs as an adult fluke.

There are a number of different flukicides on the market, but certain products are only effective against certain stages, with the majority not covering early immature and a cohort of others only effective against adult fluke.

Consideration needs to be given on the dosage used, with a follow-up dose required where the first two stages are not treated with the initial product used.

In areas where burdens are high and farmers need to intervene quickly, triclabendazole-based products which cover all three stages can be given a few weeks post housing.

There is some known resistance to this product in certain parts of the county, so precaution is advised.

Rumen fluke is generally a far lesser issue than liver fluke in cattle. In faecal tests, the majority of animals may show low levels of rumen fluke present, but treatment is not required unless clinical signs such as scouring and weight loss are evident.

Oxyclozanide-based treatments are the only doses effective in the treatment of rumen fluke. Therefore, the correct use is required to prevent resistance issues.