The WISENT or European Bison
Although superficially similar, a number of physical and behavioural differences are seen between the European bison and the American bison.
The European bison has 14 pairs of ribs, while the American bison has 15. Adult European bison have longer legs, and thus are taller than American bison. Their hump is less prominent and the calves are smaller. The Wisent is also thinner, and is not as deep in the chest as the American Bison.
European bison browse more, and graze less than their American relatives, due to their necks being set differently, and them evolving in a forested environment of northern Europe and Russia. I have raised the American Bison as well in the past, and have noticed the European Bison do better and utilize poor pastures with more bush and low brush than their American cousins. From my experince the European Bison utilize around 30-40% of their diet from browsing compared to the 5% maybe of the American Bison.
Compared to the American bison, the nose of the European bison is set further forward than the forehead when the neck is in a neutral position. Their faces are shorter and not as wide as well.
The body of the European bison is less hairy, its tail is hairier and longer than that of the American species. The horns of the European bison point forward through the plane of their faces, making them more adept at fighting through the interlocking of horns in the same manner as domestic cattle.
The rutting season occurs from August through to October. Bulls reach sexual maturity at the age of two, while cows do so in their third year. Breeding is normally done buy the older bulls as they are dominant. When Wisent and American Bison are in mixed herds, the Wisent bulls tend to be more dominant at breeding time. Cows usually have a gestation period of 264 days, and typically give birth to one calf at a time, normally in May.
On average, calves weigh 40-50lbs at birth, smaller than the Amerian Bison. Body size in males increases proportionately to the age of 6 years. Wisent have a slighter slower growth rate than their American cousins, but they also require less feed as well.
European bison have lived as long as 40 years in captivity, although in the wild their life-spans are shorter. Productive breeding years are between 3 and 25 years of age in females, and up to 15 years of age in males.