Swiss chard is safe in rotation but, like spinach, it's high in oxalates that bind calcium — so offer it occasionally rather than daily, especially for laying hens.
Keeper's noteTreat it exactly like spinach: fine now and then, rotated with low-oxalate greens. The colorful stems are safe too.
What to watch out for with swiss chard
Swiss chard is nutritious (vitamins A, C, K), but its oxalic acid binds calcium and reduces absorption. For most pet parrots an occasional serving is harmless; for egg-laying hens and birds with calcium concerns, frequent chard is best avoided in favor of low-oxalate greens like kale and bok choy.
How to serve it
A leaf occasionally, washed well; rotate with other greens.
Limit for laying hens and birds on calcium supplements.