Collard greens are otherwise known Collards and are loose-leafed cultivars of Brassica oleracea, part of the Acephala group which also contains cabbage and broccoli. The plants are grown for their large, dark-colored, edible leaves and as a garden ornamental, mainly in Brazil, Portugal, the southern United States, many parts of Africa, Montenegro, Bosnia and Herzegovina, southern Croatia, northern Spain and in India.
So can rabbits eat collard greens?
Lets take a look at their nutritional data and find out more. In particular, their calcium, sugar, fat, fibre, sodium, and phosphorus content is of particular interest.
Nutritional value per 100 g (3.5 oz)
Energy 151 kJ (36 kcal)
Carbohydrates
7.1 g
Sugars 0.57 g
Dietary fiber 2.8 g
Fat 0.41
Protein 2.97 g
Vitamins
Vitamin A equiv.
beta-carotene
lutein zeaxanthin
(72%)575 μg
(63%)6818 μg
10898 μg
Thiamine (B1) (4%)0.047 mg
Riboflavin (B2) (10%)0.115 mg
Niacin (B3) (4%)0.635 mg
Pantothenic acid (B5) (2%)0.115 mg
Vitamin B6 (9%)0.114 mg
Folate (B9) (19%)76 μg
Vitamin C (32%)26.4 mg
Vitamin E (8%)1.25 mg
Vitamin K (594%)623.2 μg
Trace metals
Calcium (21%)210 mg
Iron (9%)1.12 mg
Magnesium (8%)30 mg
Manganese (32%)0.663 mg
Phosphorus (4%)27 mg
Potassium (5%)251 mg
Sodium (3%)50 mg
Zinc
source wikipedia
As you can see collard greens contain a little phosphorus, sodium, a high acidic content, but a very high calcium content.
This means that rabbits cannot unfortunately eat them and are a food to avoid as far as bunnies are concerned.