By Debbie James

A Pembrokeshire goat meat farm involved in an on-farm study into drench resistance in goats says the findings of the research will enable more effective parasite dosing in herds, leading to improved daily live weight gains and reducing time to slaughter.

Damian and Meg McNamara have historically had a low parasite burden in the Boer cross herd they run at Moat Village Farm, New Moat.

Their herd is among four in Wales involved in the European Innovation Programme (EIP) project in Wales.

On some of the farms, evidence of worm resistance to both clear and white wormers was found in faecal egg count (FEC) sampling during initial groundwork in the first year of the project.

All the project farmers routinely FEC sample however this does not differentiate between teladorsagia, trichostrongylus and haemonchus (barber pole), or the less harmful bunostomum and oesohpagostomum.

Without identifying the species of worm present in the FEC, it is not possible to know which species, if any, show resistance, says Kate Hovers, the veterinary surgeon working with the group.

With a higher than usual incidence of haemonchus being reported nationally in 2020 and sudden heavy worm infestations in the herds participating in the project, composite FEC samples that showed high levels of worm eggs were revisited and a special stain for haemonchus carried out.

Ms Hovers said this test confirmed that haemonchus accounted for 94 per cent of the worms present in the dung samples on one farm and a high percentage on two others.

This allowed targeted treatment with levamisole which has currently proved an effective treatment for haemonchus in two of their herds, she reports.

As goats are known to be particularly sensitive to the active ingredients within this wormer, they were dosed at 1.5 times the recommended dose rate for sheep - at present there is no published licensed dose rate for this anthelmintic treatment of goats.

“We are using treatments that target all gut worms but we are testing efficacy against haemonchus as some have been less than effective against other worms but have proved to be effective against haemonchus currently on these farms,” says Ms Hovers.

The EIP study is aiming to establish a technical solution to the lack of clarity around a suitable dose rate for goats.

Goats metabolise toxins quicker than sheep and this could potentially promote anthelmintic resistance within herds, leading to a reduced effectiveness of wormers across the species.

“It should also be noted that goats can experience toxicity where sheep might not so seek professional advice on dose rates for goats,’’ says Ms Hovers.

The implications of the simple finding from the stain test meant that worm treatments not fully effective against teladorsagia could be used.

These were found to be fully successful against haemonchus.

This is significant for the management of all sheep and goats if it extends the effectiveness of the existing five drench families, says Ms Hovers.

For the McNamaras, no anthelmintic resistance was detected, allowing treatment with white wormers to continue.

Routine regular FEC was already an established protocol on their farm but post-treatment FECs administered through the project have better informed their decision making around treatments.

Pre- and post-treatment samples are analysed at the Veterinary Laboratories Agency (VLA) Centre in Carmarthen.

One of those tests detected Haemonchus.

“We had a very low worm count, it was rarely higher than 50 eggs per gram, but it was slowly creeping up,’’ said Meg.

“The speciation test pinpointed Haemonchus as the cause and we were able to treat goats individually and with the correct wormer.’’

When the project first started, the McNamaras had one of the biggest goat meat herds in Wales but they have now downsized from 500 to 35 to balance the demands of the farm with supporting their young son, Iori, who has cerebal palsy.

The scaling down of their Moat Goats herd has allowed a shift from a housed system to giving goats access to pasture through rotational grazing.

“We feel confident to do this because of the support and advice we are getting from the project,’’ says Meg.



Damien and Meg McNamara carry out FEC sampling before and after drenching

PICTURE: Debbie James

The Boer-cross herd at Moat Village Farm has a low parasite burden.

PICTURE: Debbie James