The ABU described the Tudanca as “small, but displaying a lot of aurochs features” in their guidelines , and in my opinion this is accurate. My very first aurochs reconstruction done by photo manipulation was based on a Tudanca bull:
|Modified Tudanca bull from Wikimedia Commons,|
horns of a Maronesa bull
Wikipedia states that Tudanca cows reach 135 cm at the shoulders and a weight of 320 kg, what sounds plausible, and bulls 150 cm and 420 kg. The height of 150 cm is plausible as well, but 420 kg are very likely too light for bulls with this body conformation. For comparison, a Heck bull with 145 cm shoulder height weights between 600 and 900 kg [2,3]. According to the DAD-IS (Domestic Animal Diversity Information System), Tudanca grow 165 and 160 cm at the withers and 650 and 450 kg (male, female, respectively). The shoulder heights are likely exaggerated, but the weight data sounds plausible.
Tudanca is one of the very few aurochs-like breeds that is still numerous, counting 12.230 individuals in 2011 (DAD-IS). This is four times the number of Heck cattle. Tudanca live in the Cantabria uplands, where they cope with a humid and cold climate.
The bulls are not long-legged and therefore look heavy, and their snout is shortened. But the have a well-developed hump and an S-shaped backline, and they have prominent forelocks – a feature that I appreciate very much, it is historically well-supported that European aurochs had them, and they give a kind of wild and masculine appearance. The cows have longer legs, though their hump is not as well-developed. The horns of Tudanca are comparably long, but their tips curve outwards in a corkscrew-like manner, resembling those of some Maronesa cows. A lot of Tudanca cows have horns facing strongly outwards, like a lyre pulled apart. The colour of Tudanca lacks phaeomelanins and therefore is grey. The sexual dimorphism is reduced, but bulls are darker than cows in general. Cows have a prominent ocular ring, which is most likely is a juvenile feature.
The ABU once did a Tudanca x Heck cross, but were not impressed by that combination. I also think that Tudanca doesn’t add anything to Taurus cattle except more undesired features. The breed, on the other hand, is used by the Tauros Project. There are Highland x Tudanca cows (photo) covered by a Sayaguesa, and Sayaguesa x Tudanca cows covered by a Limia (video).
Now, be delighted by some nice photos of beautiful Tudancas:
 Margret Bunzel-Drüke, Carsten Böhm, Peter Finck, Gerd Kämmer, Rainer Luick, Edgar Reisinger, Uwe Riecken, Johannes Riedl, Matthias Scharf, Olaf Zimball: ''„Wilde Weiden“. Praxisleitfaden für Ganzjahresbeweidung in Naturschutz und Landschaftsentwicklung.'' 2. Auflage. Arbeitsgemeinschaft Biologischer Umweltschutz im Kreis Soest, Bad Sassendorf-Lohne 2009, ISBN 978-3-00-024385-1.
 Julia Poettinger, 2011: Vergleichende Studie zur Haltung und zum Verhalten des Wisents und des Heckrinds.
 Cis van Vuure: Retracing the Aurochs - History, Morphology and Ecology of an extinct wild Ox. 2005.