There are a wide range of commercial food mixes or compressed food pellets specifically designed for rabbits available and these usually consist of a variety of grains, pellets and dried vegetables and these can be fed to supplement a rabbit's main diet of grass and hay.
Provided a rabbit has constant access to grass or hay, they need only be fed a small amount of rabbit mix or pellets daily and as a guide no more than 25g per kg of the rabbit's body weight should be needed.
Food mixes and pellets specifically designed for other animals should not be given as these may not be suitable to meet the rabbit's dietary requirements and could even harm the rabbit.
Rabbit mix does not perish quickly and so may be stored for some time in dry conditions without problem.
Any changes in diet, even changing to a different rabbit mix, should be made gradually as a sudden change in diet can cause the rabbit to become ill.