Genetic Selection for Dairy Traits and Resistance to Mastitis and Gastrointestinal Nematodes Has No Impact on Cryptosporidium spp. and Eimeria spp. Natural Infections in Blond-Faced Manech Lambs

Résumé fourni par la source

(1) Background: Sheep have been selected to improve their milk production. Some local dairy breeds, such as the Blond-Faced Manech (BFM) in south-west France, also select for resistance to mastitis and gastro-intestinal nematodes. However, genetic selection can also deteriorate certain traits, to the benefit of improving others. Breeders are particularly concerned about infections by digestive protozoa of the Cryptosporidium and Eimeria genus, which infect lambs at an early age and can compromise their future dairy careers. (2) Methods: 159 ewe lambs form geneticaly selected sire for milk production trait, mastitis and gastroinestinal nematode resistance, were monitored in 11 BFM farms. Individual fecal samples at 15, 30, 60 and 120 days of age were performed to detect infections by Cryptosporidium spp. (PCR targeting 18S rRNA and sequencing) or Eimeria spp. (Fecal count and morphological examination of oocysts) with species identifications. All infections remained asymptomatic. The genetic selection of rams did not affect the infection of ewe lambs for Cryptosporidium or the intensities of oocyst excretion of Eimeria species in their offspring. (4) Conclusion: This result does not indicate that genetic selection leads to a higher susceptibility of ewe lambs to Cryptosporidium sp. and Eimeria sp. natural infection in BFM breed.

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