Parasite Resistance - Serum IgA

Breeding for Parasite Resistance – Measuring IgA levels in blood serum

Research at Glasgow University has shown the antibody responses against the larval stage of Teladorsagia circumcincta, (an important member of the Strongyles family) can be used as a biological marker for host response to infection.

This potential phenotype provides a new way to identify genetic differences between sheep in their resistance to worm challenge. High levels of IgA have been shown to regulate both worm growth and fecundity – leading to a decrease in egg output.

These differences will be even more useful in a breeding programme, where they can be converted into breeding values.

In 2020, as a one off activity AHDB funded a large project to collect Serum IgA and FEC measurements. From this data SRUC have estimated encouraging heritabilities for Serum IgA (~35%) and in one breed, they also found an encouraging genetic relationship with FEC traits.

While acknowledging the practical application of this new measurement into breeding evaluations is at an early stage, these results are encouraging. AHDB are currently funding work at SRUC to incorporate this data into future breeding programmes and deliver this service to Signet clients in 2022, having provided participating breeders with some preliminary EBVs in 2021.

Please see Parasite Resistance - IgA page for more information