Multiresistance of gastrointestinal nematodes (GIN) to anthelmintics is an important issue in dairy sheep farming and genetic selection of resistant animals is one of the sustainable solutions to overcome it. In France, the ovine selection scheme is based on elite rams nucleus per breed, raised indoors and gathered in breeding centers from which the genetic progress is spreading. Therefore, strictly identical parasitic challenges are possible for all rams in order to collect standardized phenotypes of resistance or susceptibility to GIN. Since many years, young rams of two dairy breeds, Blond-Faced Manech (BFM) and Basco-Bearnaise (BB), are exposed to two successive Haemonchus contortus experimental infections, lasting one month, separated by a rest period of two weeks. Fecal Egg Count (FEC) and Packed Cell Volume (PCV) are individually measured at the beginning and the end of each experimental infection. Based on 1113 and 254 measured rams in BFM and BB breeds respectively, heritabilities of the FEC in first infection (FEC1) were 0.16 and 0.37 in BFM and BB respectively whereas the heritabilities of FEC in second infection (FEC2) were 0.34 and 0.3. Genetic correlations between FEC1 and FEC2 were high in both breeds (0.86 in BFM and 0.6 in BB). By contrast, heritabilities of differences of PCV between the beginning and the end of both infections were lower: 0.17 and 0.18 in BFM versus 0.11 and 0.08 in BB. Genetic correlations between the difference of PCV in first and second infections were poor (0.09 and 0.02 respectively). According to these data, this protocol can provide an individual estimated breeding value on resistance to GIN. Moreover, the most susceptible rams are discarded from the selection scheme since 2017. The project of a phenotyping platform in southwestern France will make possible the extension of this protocol to other breeds and small ruminants production systems.