There are many manufacturers of rabbit feed, and your own local feed mill should be able to assist you in producing a diet for your rabbits. In commercial rabbit production, the diet of their rabbits is strictly controlled exclusively through pelleted food. Whilst some rabbit growers prefer to feed their rabbits ad lib, this actually reduces their feed intake. If you feed an animal, twice a day, then the animal is eager to eat at both times of the day and actually ends up eating more.
Always ensure that fresh water is available too, as water intake also affects dry material intake. The water must not be too hot or too cold either, as this reduces water intake, and hence feed intake.
Rabbits however are well-known for their interest in eating anything green, from carrot tops, which they particularly like, to dandelion leaves. They can also eat vegetables such as carrots but fruits such as apple (without the pips), should only be given in moderation.
Check the stools of the rabbit to identify if they are well. Different foods can be added in slowly, but by checking their stools for diarrhea, you will be able to identify if there is anything upsetting them. Rabbits can stomach upsets very easily.
Rabbits eat at nighttime too, so food should be available at all times. If you are giving your rabbits additional food sources other than pellets, then ensure that hay is available all the time.
Does will eat 100 grams per day, but when pregnant after rabbit breeding, she will increase her intake to 160 grams. This jumps to 350 grams when she is lactating.
In conclusion then, for commercial rabbit farming use pelleted feed only, but for other rabbit production ventures your rabbit feed can be a mixture of pellets, hay and a mixture of greens and vegetables, with also a very limited supply of fruit, and observe your rabbit for any abnormalities when introducing a different ingredient in their diet.