Azolla & Duckweed for Livestock Feed - When Does it Make Sense?

[Shaun_Snoxell]

What is your experience in using azolla or duckweed as a low cost livestock feed?

Azolla and duckweed are floating aquatic plants, that can multiply very quickly in ideal conditions. They are relatively high in protein and energy. These plants can be used as a livestock feed for ruminants and also in small amounts for pigs and poultry.

Azolla and duckweed are widely used for livestock feed. However there are some common challenges around pest management and infrastructure maintenance in intensively managed azolla and duckweed cultivation. It is also not clear to what extent typical use of azolla and duckweed actually reduces feed costs or improves livestock performance.

I’m trying to learn more about when aquatic plants make sense as an option for poultry feed.

What is your experience? When has azolla and duckweed for livestock feed been successful and why? If it hasn’t been successful, why not?

For those looking to learn more about duckweed and azolla, ECHO has developed some resources on this.
See an ECHO Development Note on this here: Aquatic Plant Production | ECHOcommunity.org
See a video on setting up azolla and duckweed production here: https://youtu.be/-ZZ8HqZWzZY?si=eIWUe125xzibDjmP

[M.E]

Hello

I am in the process of setting up a duckweed and azolla. I plan to use for human consumption though. Since i am not a meat eater, this will be my primary source for protein. i will keep you posted on how it goes. Unless your specifically looking for animal use of Azolla and Duckweed (Wolffia Globosa)?

[Shaun_Snoxell]

Thanks @M.E ,

It would be interesting to hear how you go with your Wolffia Globosa. For livestock feed, use of Lemna minor and similar duckweed species is more typical, as they are easier to harvest and higher yielding.

I’m especially interested in how people have integrated duckweed and azolla as part of their livestock feed.

[Jeremy_DuCheny]

Great video!

I’ve grown lemna minor here in a temperate climate in buckets. I’ve read that adding manure increases the protein content. Right now it seems like a supplement to the traditional feed mix.

Some things I’m wondering:

If it’s true that you can use manure to increase protein content, what amount of manure is ideal to teed it? And what kind of manure? For example, is this chicken manure or some other kind of manure? Composted or not? I assume the heat with the chicken manure would affect plant growth just like non-aquatic plants.

What’s a good ratio for adding lemna to the feed?

Can it move beyond a supplement if you’re free ranging? Can it provide enough protein, for example.

Does it store well if dried?

Thanks! Looking forward to the conversation.

[Shaun_Snoxell]

Thanks @Jeremy_DuCheny! Good questions.

Manure for Fertility
Increased fertility (especially nitrogen) can increase duckweed (Lemna minor) protein percentage. The faster growth rates from higher fertility will also increase total protein yield, which is potentially even more useful.

The question of what type of manure is tricky, as even manure from the same species will differ in nutrient concentration. What matters is the nutrient content rather than the species. We have tried with both aged and fresh cow manure, and fresh poultry manure here. All result in increased growth rates, but there is little consistency in the results. Poultry manure typically has much more concentrated nutrients. Too much can ‘burn’ the plants, but we haven’t yet added enough to observe this. We are also careful with adding poultry manure to water than then could end up fed back to poultry - it needs to be rinsed and there is still a disease risk.

We’ve done trials with different rates of fresh cow manure and the impact on both duckweed and azolla growth. A slurry with a ratio of 1 part manure to 19 parts water, applied at 1 liter to 6 liters of water (around 15% by volume), was our most productive treatment. If your tank was 100 liters, this would work out to be around 1kg (maximum) of cow manure.

The figure below shows the results of two simple trials we did on cow dung slurry added to duckweed. One trial was in very low light and the other in medium/high light conditions, but they had the same manure treatments added. Treatment T10 is the ‘recipe’ I describe above.

Practically, you would need to give it a try and observe. Adding 1% manure by volume would be a good starting point.

Ratio for adding duckweed to feed
There is quite a bit of research suggesting dietary inclusion at 5-10% of dry matter fed typically improves poultry production. Over 15% often leads to production losses (Sońta et al., 2019). Because fresh duckweed is usually more than 90% water, this means that 5% duckweed on a dry weight basis is closer to 33% by fresh weight. Chickens will probably refuse to eat this much fresh duckweed.

The actual amount to add will depend on the other ingredients. Duckweed is reasonably high in protein but also high in fiber.

Practically at a small scale, providing duckweed as a supplement up to the appetite of the chickens is a good place to start. If you are formulating and pelletizing feed for example, then you’d want to calculate out the least-cost ration, making sure duckweed is no more than 10-15% on a dry matter basis.

Duckweed by itself is not going to provide enough protein for optimal production in a commercial system. It might allow you to reduce the amount of higher cost protein food sources. For semi-scavenging chickens in the tropics, providing duckweed as a supplement will likely increase protein intake.

Storage
Yes! If dried enough it will store well. The drier it is the longer it will store.