The need for alternatives to anthelmintic treatments continues and as part of an ongoing pan-European project, Scotland’s Rural College and the Soil Association are investigating how changes to nutrition can help sheep cope with parasite burdens.
In particular, the role of heather, which is high in condensed tannins, and a naturally occurring fungi, duddingtonia flagrans, is being investigated.
Dr Spiridoula Athanasiadou, who leads the research at SRUC, explains this work is part of the Replacement of Contentious Inputs in Organic Farming Systems’ (RELACS) project, a European funding project which started in 2018 and will run until 2022.
Dr Athanasiadou says: “Heather contains condensed tannins, and past research has demonstrated a significant anthelmintic effect of condensed tannin-containing plants.
“Goats grazing heather reduce their parasite burden, and there is a possibility that hill sheep will graze on heather leaves.”
She explains that as part of the RELACS research in vitro testing has been carried out to look at whether heather would stop eggs hatching and also whether it had an impact on larvae motility.
Heather from different countries, including the UK, was tested, with differences between heather picked in spring and in summer also analysed.
Dr Athanasiadou says: “The heather extracts from Scotland and Spain were the best at reducing the amount of eggs hatching.”
She adds there is also a seasonal effect, and in general heather picked in spring is the most active against parasites.
The next stage of this research will be to do some animal trials, to see whether these laboratory results are replicated in the animal.
As heather grazed naturally by sheep can be minimal, this animal trial will see heather cut and carried to the animal. And in the future, the viability of heather in a pellet formulation may be looked at.
The second strand of the research is looking at a naturally-occurring fungi, which works by killing the larvae on pasture.
Dr Athanasiadou says: “Spores are fed to the animals, and these then go through the animal’s digestive system and are delivered into the faeces where they come into contact with the larvae and kill it.
“Research has shown this fungi can reduce pasture contamination by up to 70 per cent.”
While not commercially available in the UK, it is available in Australia and for this research a product produced in Switzerland will be used.
Dr Athanasiadou says this is a naturally-occurring fungi, which needs to be fed to the animal in larger quantities to have the desired effect.
She says: “The spores do not develop in the sheep, and as this fungi is specific to the parasites, there is no negative effect on the animal itself.
“People have tried spreading the spores on the faeces but this does not have the same effect as feeding it to the animal.”
The next stage in this project will be the formation of farmer focus groups to look at the cost and benefits of alternatives such as fungi and heather, and whether they can be used together to optimise efficiency.
“We then want to get some farmers involved in some on-farm research next summer. For this the farmers will manage part of their flock using heather and/or fungi and compare it against existing management strategies.
The sheep will be monitored for weight gains, finishing times, faecal egg counts and the use of anthelmintic drenches.
“We are looking for farmers who are interested in alternatives to anthelmintics and are willing to try something new on their farm.”