The epidemiology of gastrointestinal nematode infections in two beef cow-calf herds in Alberta and Quebe

A herd of purebred Horned Hereford cattle was monitored in Alberta from April 1988 to November 1989. In Quebec, an Aberdeen Angus herd was monitored from May 1988 to November 1989. Parasitological evaluations included fecal egg counts and larval culture, herbage sampling for determination of infective larvae on pasture, the use of tracer calves for numeration and speciation of nematode burdens acquired while grazing with resident animals.;The mean fecal egg counts of cows at both study sites were greatest in the spring prior to turnout to summer pasture. Strongly egg counts of calves were very low until four to six weeks after turnout to summer pasture. The number of infective larvae recovered on pasture in spring was very low and peaked in August, September and October. Tracer nematode burdens were low in the early grazing season and peaked in July and August (Alberta) and September and October (Quebec). The most prevalent genera of parasites found were Ostertagia, Cooperia and Nematodirus.;Patterns of infections were similar for both study sites.;Data suggest that high fecal egg counts of cows in spring may serve as an important source of pasture contamination for calves. (Abstract shortened by UMI.).