A group of Lleyn breeders is working towards combating prevalence and anthelmintic resistance by looking at new measures for worm control.
Parasitic roundworms are a significant cost to UK sheep producers, estimated to be £84 million per year in treatment and lost productivity.
Therefore, the group’s aim was to find a way for farmers to select superior animals on the basis of maternal EBVs and help to improve disease control through genetic selection.
Research was carried out by the Moredun Foundation in collaboration with Harper Adams, AHDB and Signet.
Speaking at the Moredun Foundation sheep and cattle health and welfare day at Harper Adams, senior lecturer, Kate Phillips said: “Harper Adams have a flock of 1,000 Lleyn sheep on a rented farm near Telford which is part of the performance recorded breeders group.
“So we decided to offer our services and do an in-depth look at new ways to select sheep which are resistant to worms.”
The research aimed to find ways of genetically selecting animals that are naturally more resistant to worms than their contemporaries. A group of 20 Signet recorded Lleyn breeders took part in the study.
An increased number of farmers are using faecal egg counts (FEC) to decide when they should treat their sheep for worm infestation, but the aim of the study was to develop a less messy technique to help in selecting animals in a more simple and reliable way.
Mrs Phillips said: “We applied for a European Innovation Partnership grant to take a closer look at faecal egg counting and saliva immunoglobulin A (IgA) as predictors of worm resistance in sheep.”
The group of breeders carried out FEC collections and saliva samples on individual animals, which amounted to about 3,000 samples per year across the whole group.
“FEC is not much fun and an individual sample must be collected from each animal, which can be a very messy job especially with animals under significant worm challenge.
“The other technique is more hygienic, soaking a dental swab in the sheep’s saliva, putting it into a tube and sending it to the Moredun Foundation,” said Mrs Phillips.
IgA is produced in saliva as an immune response to the worm Teladorsagia circumcincta which is a key gut worm. IgA controls adult worm length, shorter worms produce fewer eggs which results in lower numbers of worm eggs in the gut.
This is an easier method of identifying animals that show a good immune response to some forms of worm infestation.
The research has resulted in the creation of an EBV for IgA and FEC, including values for nematodirus and strongyles. These EBVs are available from the BASCO website. The sheep search provides EBV data of each Lleyn ram on a number of genetic traits.
An EBV score of 100 is breed average and any score higher is above average, meaning the animal possesses greater resistance to worms.
In the first year of the project, they looked at the repeatability of carrying out a FEC and saliva IgA in 200 ewe lambs at Harper Adams, being displeased with the results they repeated the trial.
They bought six rams with either a high or low EBVs for saliva IgA and FEC crossed with six groups of 40 ewes. The offspring from each crossing were retained and some more in-depth studies have been carried out on saliva IgA.
Further analysis of the results is taking place and they hope to produce some useable findings for the wider industry. Some other breed societies have shown interest in developing EBVs as one way they might select breeding females and rams, on the basis of improved worm resistance.