Aquatic Plant Provides Fuel for People and Food for Pigs

Lemnaceae, commonly known as duckweed, is a small, free-floating aquatic plant with great potential for environmentally friendly applications. It can be used for the production of ethanol, biodiesel, and plastics. Research at the University of Illinois indicates that duckweed may also be a good protein source for swine diets.

"Duckweed yields more protein per acre than soybeans," said Dr. Hans H. Stein, professor of animal sciences at the University of Illinois. "It is easy to harvest, and because it grows in water it doesn't compete with food crops for land. This makes it a very exciting crop for a variety of uses, including animal feed."

Parabel’s Lemna protein concentrate is produced by extracting protein from de-oiled and dehydratedLemnaceae biomass. "Lemna protein concentrate contains approximately 68% crude protein, so it has the potential to be a very good protein source," said Stein. "Lemna meal is already fed to cattle and poultry. However, there are no published data on the nutritional value of lemna protein concentrate fed to pigs."

Stein's team conducted three experiments to determine the energy concentration and the digestibility of energy, phosphorus, and amino acids in lemna protein concentrate fed to growing pigs. Results indicated that the apparent total tract digestibility (ATTD) of gross energy was less in lemna protein concentrate than in soybean meal or fish meal, but the greater concentration of gross energy in LPC resulted in lemna protein concentrate having concentrations of digestible and metabolizable energy (4,076 and 3,571 kcal/kg) that were close to values for soybean meal (4,044 and 3,743 kcal/kg) and fish meal (3,878 and 3,510 kcal/kg).

The concentration of phosphorus in lemna protein concentrate was 0.51 percent, which was slightly less than that in soybean meal (0.62 percent) and much less than that in fish meal (3.09 percent). There was, however, a tendency for a greater standardized total tract digestibility of phosphorus in lemna protein concentrate (72.8 percent) than in fish meal (65.6 percent) or soybean meal (62.8 percent).

The standardized ileal digestibility of most indispensable amino acids was greater in fish meal than in lemna protein concentrate, but the overall digestibility of amino acids was the same in fish meal and lemna protein concentrate. The mean digestibility of all amino acids in lemna protein concentrate was 80.25 percent, and digestibility values were 75 percent or greater for all indispensable amino acids.

"The amino acids in lemna protein concentrate are well digested by pigs," Stein said. "Our results indicate that if lemna protein concentrate is included in diets for pigs, amino acid digestibility and the energy value of the diets will not be compromised."

The study, "Concentration of metabolizable energy and digestibility of energy, phosphorus, and amino acids in lemna protein concentrate fed to growing pigs," was published in a recent issue of the Journal of Animal Science. It was co-authored by Oscar Rojas and Yanhong Liu of the Stein Monogastric Nutrition Laboratory at the University of Illinois. The research was funded by Parabel, Melbourne, FL.

The full text of the paper is available online at http://www.journalofanimalscience.org/content/92/11/5222.full.

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