Is a moose an antelope

its kinda difficult to get what you mean with that.. do you mean to ask if they're monogamous? or if they continue mating each year until death? the answer to those questions are no, and yes respectively.

male elk, known as a "bull", like most members of the deer family, participate each year in whats known as the "rut". they will compete with each other in various ways such as antler sparring, to win the right to mate with the female a "cow". they will do this with as many cows as possible, as many times as possible. some bulls will mate up to a dozen times with a single cow, as the estrus cycle (when she is able to become pregnant) is only a day or two.

an elk will continue to do this until it is no longer able to, though most are killed by a predator before this happens

it may be worth noting, that in a small herd of elk, you may see up to twenty cows per bull, because the bull is waiting for the time of year when he can mate with all of them. however when that time comes, many other bulls will begin following them as well.