Bison, commonly known as buffalo, were obviously a vital part of the fort’s business as both a food source and commodity for the robe trade), but they also were part of the post’s livestock. Matt Field wrote in 1839, “At Fort William we saw two buffalo calves grazing with the domestic cattle, and displaying no indication whatever at discontent at the situation. The poor cow, however, was obliged to be tied before the little buffaloes could get nutriment from her, for they had an ungentle fashion of handling the udder which she considered somewhat unusual."
Dick Wooten, a hunter for Bent’s Fort, "came across twin buffalo calves whose mother had been killed by the hunters. The gentle little creatures followed him back to the fort, where he put them to suck on a good-natured milk cow."
“The east wall of the fort stuck out at an angle enclosing a pie-shaped yard for poultry, cows, sheep and goats, and for various tamed creatures of the plains - a white bear, two or three buffalo calves, and cages of wild birds" according to an interview with Nicholas “Cheyenne" Dawson as quoted in Janet LeCompte’s Pueblo, Hardscrabble, and Greenhorn.
Buffalo calves were found in most outposts in the West including Fort Leche, and others. At Bent’s Fort it was not unusual for the hunters to bring home the calf after shooting a buffalo cow. Once raised, some buffalo were even taken east with the cattle to sell as a curiosity. Others were slaughtered at the fort for the meat which was considered far tastier than beef.
Source: U.S. Department of the Interior, National Park Service