No, you should not use MMA gloves on the heavy bag and here's why...
Heavy Bag training is an awesome workout. Trying to punch a bag weighing upward of 50kg, for minutes on end, without stopping is an incredibly hard workout. It helps builds stamina, strength, and good technique. When done right it can strengthen your wrists and sharpen the technique.
It is however extremely tough on your body. Hitting a heavy bag over and over without proper protection puts an extreme level of strain on your hands and wrist. The impact of each strike against something so heavy sends shock waves back up the body. This can cause micro-fractures to bones, tears to tendons, soft tissue bruising, and cause wrist sprains. All of which take time to heal, and can put you out of training whilst it heals.
All of this can be avoided by using the correct protective gloves when hitting the heavy bag. Unfortunately, MMA gloves are not suitable for this purpose.
MMA gloves are extremely thin and are designed to enable the types of moves an MMA fighter performs. This can be anything from punches and chops, through to clinches and grappling. The padding is extremely thin however and the gloves themselves usually weigh less than 4 oz. It is impossible to wear hand wraps under MMA gloves so this means you have no protection for your wrist. The gloves are usually very short and offer no wrist stabilization.
A heavy bag workout can cause significant injury to hands, knuckles and wrists if the incorrect gloves are used. Bag gloves or boxing gloves have significant levels of padding to offer maximum protection to the knuckles and wrist. It is much better to purchase a set of gloves designed for use on the heavy bag.
Recently some new types of MMA bag gloves have been introduced. Thet offer gel inserts and long wrist supports to prevent you from spraining your wrist. Whilst these are better, they are no substitute for using the correct type of gloves when training the heavy bag.