When our chickens and ducks free range in the evenings before dark, I watch closely to see what kinds of things they seem to like best to forage so I will know what type of goodies to pick for them when they are confined in their pen. Dandelion greens, chickweed and tender grasses seem to be on the top of their list, along with small pebbles they use as grit to grind their food. They also of course love earthworms, crickets and bugs. Another favorite is clover.
The clover confused me because I have seen clover mentioned on several lists of things chickens shouldn't be eating. But normally the chickens know best what is good for them and what isn't, especially when offered a selection of plants on which to graze.
So I decided to do some research and find out the real story about clover. I consulted a vet, a poultry expert and also an herbalist, read a few studies, and here's what I found out about clover:
Clover is a highly nutritious cool weather perennial plant in the legume family. It is of exceptional benefit as a forage substitute when grass is scarce since it is so nutrient-dense. There are several varieties of clover including red, white and purple, but they all have similar nutritional value. Clovers are high in calcium, niacin (most likely why our ducks love clover!), potassium, Vitamins A and B, iron and protein. Clover is a detoxifier and stimulates the liver and digestive system. It also aids in respiratory and circulatory health, being an anticoagulant.
And therein lies the reason clover often appears on lists of what not to feed chickens. Clover contains coumarin which is a blood thinner. So while it does help with good blood flow and lower blood pressure, particularly if clover gets moldy the presence of certain fungi cause coumarin to turn into a toxin that can cause internal hemorrhaging. This is more of a problem with cut clover being baled up in hay for horses and other livestock and then getting wet, which will allow the fungus to grow. Toxicity doesn't generally occur under normal grazing conditions.
Clover, a relative of soy, also contains a form of estrogen, called an isoflavone, which can interfere with animal reproductive systems in large enough quantities, but in a free grazing situation or being fed free-choice in reasonable quantities as part of a multi-faceted diet of grasses and weeds, it should not pose any problem. After all, nearly anything in large enough quantities can have negative health effects. Daily vitamins offer wonderful health benefits to humans, but swallowing an entire bottle at once would probably kill you.
So in short, clover is a wonderful addition to your flocks' diet. Don't shy away from offering clover, preferably mixed with other weeds and grasses if you are cutting the clover and hand feeding. Your chickens will know how much they need for the nutrients and eat accordingly. At least now I understand why clover is cautioned against and can make my own educated decision about it.
Note: Chamomile, cinnamon, licorice, strawberries, cherries and apricots also contain coumarin.