Collard greens are one of the vegetables that belong to the Brassica oleracea which has other cultivars such as broccoli, kale, cauliflower, cabbage, savoy, Brussels sprouts, kohlrabi, and gai lan.
Known by various names such as mbida in Zimbabwe, Sukuma wiki in East Africa, Couve in Brazil and Portugal, and haakh in Kashmir, This nutritious vegetable has carbs, proteins, vitamins A (lutein zeaxanthin and beta-carotene), vitamin B1, B2, B3, B5, B6, B9, C, E, and K.
Furthermore, it has minerals such as calcium, iron, magnesium, manganese, potassium, phosphorus, sodium and zinc as well as a lot of water.
Do bunnies eat collards?
Yes, your bunnies can have collard greens.    They are one of the bunny-safe green veggies together with others such as kales, cabbage, romaine lettuce, endive, turnip greens, dandelion greens, spinach and so on.
Some sources   note that this vegetable has a high amount of calcium and insists on feeding it your bunny sparingly. Furthermore, if your bunny has a kidney or bladder problem, you are advised not to feed them collard greens.
Analyzing its calcium content, we notice that it has about 140mg per 100g and medium-sized bunny requires about 510mg of calcium daily. Furthermore, you are supposed to mix at least 5-6 different leafy greens for a great nutritional mix. You can mix it with other leafy greens with low calcium quantities.
One cup of this chopped mixture is enough for a bunny weighing 2 pounds meaning the amount of collard in the mix will be little. Besides, you should always vary the various leafy greens you give your furry friend since it will enjoy their varying textures and tastes.
Feeding your pet this veggie
Like any other new food, it needs to be introduced slowly over a duration of about a week beginning with small quantities and checking how your bun’s stomach reacts after 24 hours.
If you notice any diarrhea, gas, bloating and intestinal disturbances, revert to their usual diet. Otherwise, gradually increase the quantity to the recommended amounts.
Secondly, you need to ensure that their source is free of pesticides, they have no molds and thoroughly clean them. They could be carrying some intestinal parasites including infective stages of roundworms, tapeworms, and so on. Furthermore, always go for fresh ones.
Do not replace their recommended diets with any fresh food even if they like it. Your bunnies need about 80% hay. For hay, consider brands such as Standlee Premium Western Forage Timothy Grass, Small Pet Select 2nd Cutting "Perfect Blend" Timothy Hay Pet Food or Kaytee Timothy Hay.
Fresh foods can account for 10-15% while pellets account for the reminder. Go for high fiber pellets.