Calicophoron daubneyi, a rumen fluke increasingly reported in European livestock, has emerged as a relevant parasitic threat in cattle. This study investigated the prevalence and seasonal dynamics of gastrointestinal endoparasites in 382 fecal samples from 40 beef cattle farms (26 extensive and 14 semi-extensive) in central Spain. Samples were analyzed using flotation, sedimentation, and modified McMaster techniques, complemented by PCR confirmation of trematodes and a 25-variable epidemiological survey. C. daubneyi was detected in 38.74% of samples and 77.5% of farms, surpassing Fasciola hepatica (13.09%), gastrointestinal nematodes (42.15%), and Eimeria spp. (16.75%). Mixed infections were frequent. Seasonal shedding patterns varied by parasite, with C. daubneyi peaking in spring and winter. Statistical analyses (Kruskal–Wallis, ANOVA, Mann–Whitney U) revealed significant seasonal differences and confirmed higher F. hepatica egg counts in extensive systems (p = 0.0012). Anthelmintic treatment was infrequent and mainly guided by coprological diagnosis; ivermectin, closantel, albendazole, and nitroxinil were the most used drugs, though none fully effective against C. daubneyi. Anthelmintic resistance was not evaluated in this study. These findings confirm the emergence of C. daubneyi in central Spain and highlight the need for targeted surveillance and seasonally adjusted control strategies.