Believe it or not, white-tailed deer do eat cactus. It most locations that white-tailed deer inhabit cacti are not an important whitetail food, primarily because many cacti species are not present. However, in Texas, prickly pear cactus is used to some extent, especially in western portions of the state. When the pears of prickly pear ripen in late spring, deer will readily consume these golf-ball size fruits. It does not even matter that they have small, protective spines!
In addition, deer will consume newly formed cactus pads from prickly pear. These make moisture-rich treats for deer in arid environments. Whitetail are very opportunistic and switch their diet quickly to cope with a changing environment. In fact, one study found that deer would readily consume prickly pear following a summer fire because it was the only thing available and green to eat. Luckily for the deer, fire causes the spines on prickly pear to fall off–leaving the plant defenseless to a hungry deer herd.
In short, cacti species do not comprise much of a white-tailed deer’s diet. However, cactus fruits and pads can become important whitetail foods when available or needed to survive.