Utilização de fungos nemátofagos para controle biológico parasitário em ovelhas criadas em sistema semi-intensivo

Abstract

Gastrointestinal nematodes are one of the main problems in sheep farming, affecting the productive and reproductive performance of sheep, as well as being responsible for a considerable part of herd mortality. A large part of the nematode cycle takes place in the environment, such as pastures, making it difficult to control these parasites. For many years, the use of indiscriminate dosages of anthelmintics has made it even more difficult to eradicate nematodes, as this creates constant selective pressure on the parasites, compromising the increase in resistance to existing drugs and making parasite control more difficult. The aim of this study was to estimate the effect of biological control using the product Bioverm Plus® on gastrointestinal nematode infection in sheep raised in a semi-intensive production system. Thirty-six animals were used, randomized into three groups: the control group, the anthelmintic group and the group called Bioverm Plus®, the product (an association of the fungi Duddigtonia Flagrans and Pochonia Clamydospora). Every 15 days, the action of the treatments was evaluated by collecting blood, feces and the sheep's body weight, as well as by collecting the height of the pasture. The evaluations carried out were OPG, coprocultures, VG, PPT and L3 extraction in the pasture. The results did not show a reduction in eggs per gram of feces over the course of the collections, nor did the different treatments differ statistically in the sheep's globular volume. In the collections where the temperature was reduced, the Haemonchus contortus larvae were also reduced and even disappeared, which did not happen with the Trichostrongylus columbriformis larvae, which resisted the low temperatures. By evaluating the values found in the analyses, it is possible to conclude that the predatory activity of the fungi and their development may have been affected by environmental issues, mainly temperature, the reduction in pasture intake by the sheep and the size of the area, which did not outperform the other treatments. Further studies are therefore needed under different management and nutritional conditions.