Discovering genes involved in gastro-intestinal nematode parasite resistance of sheep by using microsatellites and SNP array data

This project took place at the Research Unit: Genetics and Biotechnology of the Sardinian Agency for Agricultural Research (AGRIS Sardegna, Italy) in Olmedo, and undertook research on discovering genes involved in gastrointestinal nematode parasite resistance of dairy sheep by using microsatellites and SNP array data, supervised by Dr. Antonello Carta (


Nematode parasites are one of the major animal health constraints in sheep breeding also with a great impact upon productivity. According to the increasing consumers’ demand of healthy and drug-free products, selection for resistance to disease is a promising approach to obtain healthy products. Evidence for genetic variation amongst sheep in their resistance to gastro-intestinal nematode parasites is well documented in many breeds. Implementation of nematode resistance in breeding programs required improved understanding of genetic bases of the host-parasite relationships.

The project

The Nematode System Health Marie Curie Initial Training Network was a collaborative venture between interested scientists across Europe focused on developing a systems’ based approach to selecting animals that are genetically resistant to disease. The training program brought together expertise in parasitology, genetics, immunology, animal breeding, animal husbandry, animal behaviour, microbiology, statistics, epidemiology and mathematical modelling.

The AGRIS team

The Sardinian Agency for Agricultural Research (AGRIS-Sardegna) is the body of the Sardinian Autonomous Region to be responsible for experiments in agriculture. The Department for Research on Animal Production (before Istituto Zootecnico e Caseario per la Sardegna) is responsible for experiments in livestock and food science. The research unit Genetics and Biotecnology is the scientific reference of the National Breeders Associations for the selection scheme of the Sardinian sheep. In the last years its main topics have been the use of genomic information for selection purposes with main emphasis on disease resistance. In the framework of studying traits related to gastrointestinal parasite infections they have strong links with Prof. Antonio Scala (University of Sassari), one of the main national experts in nematodes studies.


In the framework of the EU project GeneSheepSafety an experimental population of around 1000 back-cross Sardinia x Lacaune ewes was reared, genotyped for 146 microsatellite markers spread all over the genome and recorded for several traits of potential interest in selection. A subsequent population was created by mating Sardinian rams with the back-cross ewes and their descendants. Each year 200-250 yearling ewes are introduced in the experimental flock to replace ewes which are slaughtered after their fourth lactation.

The population is organised in sire families of approximately 40 daughters. All of them are expected to produce 4 lactations. The basic measure of resistance to nematodes was faecal egg count (FEC) under natural conditions of infection. In this project, further research will be performed to confirm and fine map the most promising QTL regions detected by the initial scan and also to detect new QTLs. The resource population will be genotyped with the Illumina OvineSNP50 chip. The analysis of these data was part of the project.