Does anyone have experience with feeding duckweed as fodder or know anything about its nutrition value?
I found a research paper about using dried duckweed in diets for layer hens.
(I think it's referenced in one of the articles you linked to, but this is the actual writeup with more details.)
I think this link will go to the .pdf:
https://www.sciencedirect.com/science/article/pii/S0032579119329542/pdf
If that link doesn't work, try this one should go to a page with an abstract, that then has a link to download the .pdf:
https://www.sciencedirect.com/science/article/pii/S0032579119329542
And if that doesn't work, try googling for the title:
Duckweed, A Useful Strategy for Feeding Chickens: Performance of
Layers Fed with Sewage-Grown Lemnacea Species
(Authors are Haustetn, Gilman, Skillicorn, Vergara, and Gastanaduy)
It talks about using duckweed to replace soybeans meal and some fish meal in chicken diets. The recipe for each diet is given, with the nutritional analysis of each diet. They found reduced production when dried duckweed was 40% of the diet, but not when dried duckweed was 25% or less of the diet.
The article did mention that fresh duckweed contains large amounts of water, which limits how much a chicken can actually eat of it-- which is why they were using dried duckweed in their experiment.
Based on that, I would assume you can let your birds have as much fresh duckweed as they want, but that you probably should not expect it to make much difference in their diets (because of the high amount of water, which means low concentration of nutrients.) But as long as they also eat enough of their usual complete food, the duckweed would not cause any harm.
