Pochonia chlamydosporia no controle biológico de Fasciola hepatica em bovinos e comparação de técnicas de sedimentação de ovos

• Autor(a) principal: Dias, Anderson Silva
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1477
• topic: Controle biológico; Pochonia chlamydosporia; Fasciola hepatica; Bovino - Doenças; Biological control; Pochonia chlamydosporia; Fasciola hepatica; Cattle - Diseases; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::MEDICINA VETERINARIA PREVENTIVA::DOENCAS PARASITARIAS DE ANIMAIS

The presence of helminths causing losses in livestock in the Brazil and in the world is significant. The Fasciola hepatica is among the main agents responsible for these losses. Due to increased occurrences of problems anthelmintic resistance and failures in the control of this helminths, the use of agent of biological control have been studied and they have showed promising results. This study aims to evaluate: the action of the fungus Pochonia chlamydosporia in vitro and in vivo on eggs of F. hepatica, after passage through of gastrointestinal tract of cattle in formulations of pellets; assess the weather conditions on F. hepatica egg production and evaluate three techniques of sedimentation to quantify F. hepatica eggs in cattle faeces. Thus, stool samples were collected in cattle of treated group with pellets contained the fungus P. chlamydosporia and control group with pellets without fungus in times 12, 18, 24, 48, 72 and 96 h after administration of pellets. The ovicidal effect was observed after seven days of interaction. The fungus showed ovicidal activities on eggs F. hepatica in the samples (treated group) in all times from 12 h. Significant differences (p <0.01) in the destruction of the eggs in animals of the treated group compared to those of the control was verified. This resuts suggest employment this fungus of effectively to the control of eggs of F. hepatica. Thirty days after deworming, the animals were divided into two similar paddocks e animals received per os pellets containing 25% mycelial mass of P. chlamydosporia (group B) and pellets without fungus (group A), at a dose of 100 g, twice a week over 18 months. The mean count of F. hepatica eggs per gram of faeces was higher (p<0.01) in animals of group A (1.19) compared with those from group B (0.82). After 18 months, the animals from group B gained 42.33 kg above (17.82%) compared to those of control group (A) (p<0.01). During 18 months, monthly, cattle faecal samples were collected from the pastures of the paddocks of A and B groups and they were incubated to observe structures related at P. chlamydosporia fungus e they was identified only in sample collected in the paddock of B group. Mean number of eggs per gram of faeces of the samples collected between periods of rain (October- March) and dry (April-September) were not different (p>0.05) and, thus, it is possible that the animals can be infected by F. hepatica during all the year. The modified sedimentation techniques of Dennis, Stone & Swanson (DSS), Girão and Ueno (quatro tamises) and Foreyt were compared. The modified DSS technique was the most sensitivity (p<0.01) (48.60%). The three techniques showed a specificity of 100%. There was no correlation among the values of egg obtained by the three techniques, and significant coefficients were not observed by regression analysis. The modified DSS technique was the most effective for F. hepatica diagnosis in cattle (p<0.01). The application of this fungical formulation with P. chlamydosporia (25 %) mycelial mass was effective in reducing the availability of eggs in the environment, and consecutive, in the reinfections in calves.