Agri Kultuur December / Desember 2018 - Page 12

Table 2: Mean essential amino acid values (g/100 g protein) of four species of duckweed 1 compared to FAO reference EAA pattern. Amino acids Mean ± SD FAO reference protein Arginine 4.54 ± 0.64 - Histidine 1.78 ± 0.42 - Isoleucine 3.61 ± 0.37 4.2 Leucine 6.68 ± 0.58 4.8 Lysine 4.01 ± 0.43 4.2 Methionine 0.90 ± 0.15 2.2 Phenylalanine 4.16 ± 0.39 2.8 Threonine 3.12 ± 0.40 2.8 2 - 1.4 Tryptophan Valine 4.39 ± 0.64 4.2 Tyrosine 2.82 ± 0.44 - 1 L.gibba, S. polyrrhiza, S. punctate and W. Columbiana Destroyed during analysis 2 Source: modified from Culley et al. (1981) Conclusion: Duckweeds have received much attention because of their potential to remove mineral AgriKultuur |AgriCulture contaminants from wastewater. Definitive information has been published on the production and chemical composition of these plants, and their environmental requirements have been clearly determined. Information on the cultivation techniques of many duckweed species is also available. Due to their rapid growth, attractive nutritional properties and relative ease of production, duckweeds have generated renewed interest among fish nutritionists on their use as possible alternative sources of fish feed. References: Caulton M.S. The Biology and Farming of Tilapia in Southern Africa. Chhorn Lim, Carl D. Webster – Editors. Tilapia: Biology, Culture, and Nutrition. FAO: Nutritional requirements of Nile Tilapia. www.fao.org/fishery/affrisspecies-profiles/nile- tilapia/nutritional-requirements/en/ FAO: Fisheries and Aquaculture Technical Paper 531. Use of algae and aquatic macrophytes as feed in small-scale aquaculture. E-mail: hbs@sun.ac.za 12