Rumen ciliates (Ciliophora, Trichostomatia) in Brazilian domestic cattle feeding on diets with crescent urea levels

•Second taxonomic inventory of rumen ciliates from Brazilian domestic cattle;•Remarkable diversity of rumen ciliates associated with the Brazilian domestic cattle gastrointestinal tract, distributed in two orders, three families, 11 genera and 31 species;•Description of a new morphotype, Entodinium caudatum m. orbonuclearis.•The inclusion of urea in the diet of ruminants appears not to influence the density of rumen ciliates, suggesting that this supplementation is suitable in the formulation of low-cost animal feed. Since their discovery, rumen ciliates of domestic cattle have been reported from various geographic locations. However, until now there is only one taxonomic inventory of ciliates associated with Brazilian cattle. The present study aimed to assess the community composition, relative abundance, richness, and density of rumen ciliates in Brazilian cattle, whose feeding diets were supplemented with crescent urea levels. Across all treatments analyzed, one subclass, two orders, three families, 11 genera, and 31 species of ciliates were identified. The ciliate community composition and species richness varied among the four treatments used. However, the total ciliate density was not affected by the experimental diets. We described a new entodiniid morphotype, Entodinium caudatum m. orbonuclearis, and recorded Oligoisotricha bubali for the second time in Brazil.