Epidemiological observations on gastro-intestinal nematodes in communal land cattle from the highveld of Zimbabwe.

Monthly individual faecal samples from 12 calves, 12 heifers, 17 steers, 12 lactating and 10 dry cows from the communal lands near Harare in the Mashonaland province of Zimbabwe, were collected over a period of one year. Eggs per gram (epg) were determined and the infective larvae (L3) examined, following culture of pooled samples from each group of animals. The lowest counts were found in steers and the highest in calves. The lactating cows had egg counts as high or higher than the heifers. The general trend of epg was related to the rainfall pattern. The egg counts rose from December to reach a peak during April and May, followed by a decline and low levels during the dry period, from June to December. Cooperia, Haemonchus, Trichostrongylus, Oesophagostomum and Strongyloides (in calves only) were identified on coproculture. About 73-83% of L3 belonged to Cooperia and Haemonchus. The high level of infection by nematodes in the communal land cattle was thought to be due to overstocking, overgrazing and poor pasture quality.