Natural development of gastrointestinal helminthiasis in calves born during the dry season in Guaira, State of São Paulo, Brazil.

Abstract

Proceeding with their observations on bovine nematode epidemiology in Guaíra, State of São Paulo, the authors carried a study on the natural development of nematode infections in crossbred calves born at the dry season. The fecal nematode egg counts per gram (e.p.g.) performed every fortnight were positive at the start, in October, when calves were two months old, and reached the peak when they were five months old; cultures of faeces revealed larvae of Cooperia, Haemoncus, Oesophagostomum and Trichostrongylus. From this time on, until 12.5 months old, when the calves were slaughtered, the variable e.p.g. decreased continually, the average being, in the last examinations, 40 e.p.g. Strongyloides eggs were present in the faeces when the calves were two months old but they disappeared by the 5th month of age. The post-mortem examination revealed the following species of nematodes: Haemoncus similis, Haemoncus contortus, Trichostrongylus axei, Bunostomum phlebotomum, Cooperia punctata, Cooperia pectinata, Oesophagostomum radiatum, Trichuris discolor and Dictyocaulus viviparus.;