Interação entre Haemonchus placei, Trichostrongylus axei, Ostertagia ostertagi e Ostertagia lyrata (Trichostrongylidae) em bezerros, no Estado do Rio de Janeiro

Abstract

The interaction between the bovine abomasal species Haemonchus placei, Trichostrongylus axei and Ostertagia Oster tagi and Ostertagia lyrata was studied in 48 steers (zebu x frisean), 6-9 months old and carrying a natural nematode infection. Thirty-seven of these animals were collected in the Quatis district, municipality of Barra Mansa, Rio de Janeiro State and the rest from UEPAE-EMBRAPA-Itaguaí, RJ where the animals were assembled and divided into 4 groups at random (Groups A, B, C & D) and kept in 4 paddocks of approx. 8.300 m2. In Groups B & D the compound disophenol was used (10 mg/ kg body weight) and in 3 animals of each group, injectable levamisole (3.75 mg/kg body weight). In Groups C & D a horse grazed with the cattle in each paddock. This study is based on coprological, haematological data, and on post-mortem studies. It was seen that H. placei and T. axei, when concurrent in a host, reduce both eggproduction and number of adult worms present. The effect of 5 5 the horse, the usage of anthelmintics on the epizootiology of the abomasal nematodes, the macroscopic lesion of the abomasum, the pH of the abomasal content, and the haematocrit values of each animal were also noted. Finally, the mechanism involved in the phenomenon of interaction is d i s c u s s e d .