Fungi Isolated from Cattle Potentially Causing Economic Losses in the Production Chain

Background: Fungal diseases in bovines might cause considerable economic losses for farmers and the livestock industry due to decreased productivity caused by various factors. The most important causes described in the literature are: direct infections, secondary complications like reduced growth productivity and reproduction, weight loss, decreased milk production, production of mycotoxins, treatment costs, and even mortality. The purpose of this manuscript is to describe a retrospective data about fungal isolated from bovines at the Sector of Veterinary Mycology, School of Veterinary Medicine of the Federal University of Rio Grande do Sul (UFRGS) during a 38-year period of routine diagnosis (1986-2023).Materials, Methods & Results: Two-hundred and thirty-two (n = 232) mycological cultures were made from bovine samples from specimens of various systems [integumentary (n = 84); 27 respiratory (n = 27); reproductive (n = 41) and digestive (n = 36)] and 44 samples of quarter milk from subclinical mastitis. Culture media used were as the following: Sabouraud dextrose agar (SDA) with chloramphenicol; SDA with chloramphenicol & cyclohexamide; and yeast extract-malt agar with chloramphenicol. Trichophyton verrucosum was the most dermatophyte zoophilic diagnosticated from the hair samples. From milk samples the yeast Candida spp. was the most prevalent pathogen isolated. Samples from cattle with respiratory disorders (n = 27) showed the presence of fungi (18 = 67%) with a great majority being hyalohyphomycetes (15 = 55%). In relationship to positive cultures (49 = 64%) from abortion (77 samples), hyalohyphomycetes (n = 37) were the most isolated fungi, comprising 75.5% of the total isolates, with the genus Aspergillus spp. (n = 19; 10 A. fumigatus) being the most prevalent within this group; yeasts (7 = 14%) were the 2nd type of fungi cultured from abortion specimens. Also, some dairy and beef cattle feed samples were analyzed for fungal contamination showing various fungal species: rice straw (Fusarium sp., Mucor sp. and Aspergillus flavus); sorghum silage (Candida albicans); alfalfa (A. flavus, A. niger and Rhizopus sp.); barley (A. clavatus) and feed (A. clavatus).Discussion: The results of fungi isolated from several bovine organs over a period of 38 years are intended to emphasize the need to routinely investigate a possible fungal etiology in various clinical conditions, at least as a differential diagnosis. Mycoses affecting ruminants are usually diagnosed after the animal's death and occur after fungal propagules invade via the airborne, digestive, or intramuscular routes for subsequent hematogenous or lymphatic dissemination to various organs. Due to the fact that the fungi isolated in the present study are ubiquitous, complementary tests, especially histopathological analysis, are often necessary to ascertain with certainty that it is a mycotic condition. Knowledge of the diseases affecting cattle in Brazil, whether caused by bacteria, viruses, fungi, or other etiologies, is very important for decision-making aimed at reducing their occurrence and minimizing the resulting economic losses. The world literature cites parasitic and bacterial diseases, as well as management factors, as the most common causes of losses due to carcass condemnation. Fungi are usually more associated with meat alteration and contamination during refrigerated storage. The fungi, whether filamentous or yeasts, described in the present manuscript are recognized worldwide as being associated with the occurrence of various clinical conditions in several animal species, as well as in humans.Keywords: mycoses, ruminants, abortion, pneumonia, carcass condemnation, filamentous fungi, yeasts.