F
d ee w k c u D The search for a sustainable
protein supplement for the future Duckweed is the smallest flowering plant in the world, an aquatic plant which can be found in fresh water or wetlands in most corners of the world that do not freeze too frequently. Floating on or just below the surface of still or slow-moving bodies of water, many around the world perceive it as a pest, claiming it “clogs up lakes or ponds”. However, duckweed is anything but a pest. It is in fact somewhat more of a super plant. With properties suggesting it is under-utilised potentially as bio-fuel; as an effective bio-remediator of waste water; it is a potent fertiliser; and most importantly for the purposes of this article, it is a rich and sustainable source of protein with the potential for widespread use in animal feed, aqua feed, and as a food source for humans.
by Peter Parker, Milling and Grain magazine Question and Answer with Tamra Fakhoorian, International Lemna Assocation Duckweed expert, Ms Fakhoorian is a biologist, chemist, and co-founder of the International Lemna Association, of which she is the current executive director. Three years ago Ms Fakhoorian founded GreenSun Products, LLC; a company that has developed duckweed production systems, and product lines for both pet and human nutrition. Q. From my very limited understanding of duckweed, it seems as though it would have great potential as aqua and terrestrial animal feed in general? A. Yes, while initial commercial marketing focus is on higher value products, duckweed has been used to feed fish and land animals for decades in integrated Asian farmer settings. Researchers have been working with duckweed for nearly fifty years. We know its potential to remediate wastewater and return a large volume of high protein biomass and exceptionally clean water. This pathway is seen as completing the nutrient cycle, a real boon to sustainable production of plant protein for a wide variety of uses including aqua and terrestrial animal feeds. I love this quote by Peter Marshall: “Waste itself is a human concept. Everything in nature is eventually used.” Duckweed can help farmers mimic nature in this regard, and reap feed cost savings whilst reusing fresh water over and over. Q. What is the state of the duckweed industry? A. Current applications include: 1. Using the decades-old model of Asian small farm settings to recapture animal waste nutrient streams and use the resulting duckweed biomass as a fresh feed for ducks, fish, and swine for feed cost savings. Companies are developing integrated systems including CAFO waste streams for biomethane generation and subsequent duckweed production to be used as fresh feed supplements for cattle, swine, and chickens. (Each species has maximum feed inclusion rates due to each animal’s ability to process the high percentage of water in fresh duckweed.) Dried duckweed meal can be substituted for soya 58 | September 2015 - Milling and Grain
as a protein replacement in 10-30 percent inclusion rates, depending on the animal. 2. As a processed fishmeal replacement- lemna protein concentrate (LPC) for swine, production initially. LPC has gone toe-to-toe with 68 percent soy protein concentrate and found to produce comparable results. This is powerful given duckweed’s ability to produce at least four times the amount of protein per hectare versus that of soya, be GMO-free, and remediate animal waste streams at the same time. 3. Along with GreenSun Products, several companies are working with various strains of duckweed for human nutrition Protein levels of as high at 50 percent and above are being reported on a dry weight basis, with vitamin and mineral content heralded as well above average for green leafy crops. Additional benefits include being non-GMO, gluten-free, and organically produced. Be watching for both fresh and dried products to hit store shelves within the next couple of years. Q. What is the nutritional make up of duckweed? A. While an older table, this one is fairly reliable as far as ranges: Organic composition in the Lemnaceae, % of dry weight protein
6.8 — 45.0
lipid
1.8 — 9.2
crude fiber
5.7 — 16.2
carbohydrate
14.1 — 43.6
ash
12.0 — 27.6
Ms Fakhoorian suggested that the feed industry investigate the potential for duckweed’s nearly complete amino acid profile as being as close to animal protein as the plant kingdom can provide. In addition she provided this quote from Dr John Cross, author of the richly-detailed website, The Charms of Duckweed. The protein content of duckweeds is one of the highest in the plant kingdom, but it is dependent on growth conditions. Typically duckweeds are rich in leucine, threonine, valine, isoleucine and phenylalanine. They tend to be low in cysteine, methionine, and tyrosine.”
Q. What is the state of its current usage in the livestock feed industry? How do you believe this could be expanded? A. Studies have shown that duckweed can be included in poultry, swine, and cattle feedstocks at beneficial inclusion rates; however, the practice is not yet done on a commercial scale due to drying costs. (duckweed is 92-94 percent water on average) Solar drying or hybrid drying has been successful on a limited tonnage basis and this technology looks promising for the future.