title: Studies on the epidemiology of Ostertagia ostertagi in calves.
mesh_terms: D000018:Abomasum / Q000469:parasitology; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000469:parasitology; D010029:Ostertagiasis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D010435:Pepsinogens / Q000097:blood; D012621:Seasons; D014251:Trichostrongyloidea / Q000302:isolation & purification; D014252:Trichostrongyloidiasis / Q000662:veterinary*
chemical_list: D010435:Pepsinogens