[Characteristics of Ostertagia sp. populations in naturally infested sheep in the region of Moulay-Bouazza (Morocco)].

Sixty-six abomasa of ewes were collected monthly at the slaughter-house of Moulay-Bouazza (Morocco) during two years. The characteristics of the population of Ostertagia (mostly O. circumcincta) were studied: number of eggs per female, vulvar polymorphism, length, sex-ratio and size of the worm-burden. These parameters were interrelated and could account for the seasonal variations of the number of eggs per female.