Fresh Duckweed Research Articles

Characterization of Bioactive Metabolites and Antioxidant Activities in Solid and Liquid Fractions of Fresh Duckweed (Wolffia globosa) Subjected to Different Cell Wall Rupture Methods.

Fresh Wolffia globosa, the smallest flowering plant well-known for its favorable nutrient composition and rich content of bioactive compounds, was subjected to boiling, freeze-thawing, and mechanical crushing to reduce its excessive (95-96%) moisture level and consequent drying time. The resultant three wolffia matrixes were filtered through a plankton net to fractionate into the residue and the filtrate. The proximate composition, bioactive metabolites, antioxidant activity, and characterization of bioactive metabolites by LC-ESI-QTOF-MS/MS and Fourier transform infrared spectroscopy were made from oven-dried residues and filtrates. Among residues, crude protein (29.84%), crude lipid (5.77%), total carotenoids (TCC; 722.8 μg/g), and vitamin C (70.02 mg/100 g) were the highest (p < 0.05) for freeze-thawing against higher ash (7.99%), total phenolic content (TPC; 191.47 mg GAE g-1 dry weight), total flavonoid content (TFC; 91.54 mg QE g-1 dry weight), DPPH activity (47.46%), and ferric reducing antioxidant power (FRAP) activity (570.19 μmol FeSO4 equiv/mg) for the crushed counterpart and Chl-b in residues from boiling. No significant variation was evident in the total tannin content (TTC). Among filtrates, higher total phenolic content (773.29 mg GAE g-1 dry weight), TFC (392.77 mg QE g-1 dry weight), TTC (22.51 mg TAE g-1), and antioxidant activity as DPPH activity (66.46%) and FRAP (891.62 μmol FeSO4 equiv/mg) were evident for boiling, while that from crushing exhibited the highest TCC (1997.38 μg/g DM). LC-ESI-QTOF-MS/MS analysis identified 72 phenolic compounds with the maximum in residue (33) and filtrate (33) from freeze-thawing, followed by crushing (18 and 19) and boiling (14 and 13) in order, respectively. The results indicated that the predrying cell rupturing method significantly impacted quantitative, as well as qualitative compositions of residues and filtrates from fresh wolffia.

Effects of alkaline and ultrasonication on duckweed (Wolffia arrhiza) protein extracts’ physicochemical and techno-functional properties

Wolffia is a protein-rich aquatic plant with the potential to help address food sustainability issues; however, a more efficient extraction process must be sought due to limited yield with conventional methods. This study aimed to investigate the effects of duckweed forms (fresh and dried), duckweed-to-aqueous solution ratio (DSR), as well as alkaline and ultrasonication extractions on yields, physicochemical and techno-functional properties of duckweed protein extracts (DPE). Three extraction methods were used: alkaline extraction (AE), ultrasound-assisted alkaline extraction (UAAE), and ultrasound-assisted water extraction (UAWE). The study showed fresh duckweed resulted in a 2.5-fold higher yield and protein recovery than oven-dried duckweed. UAE significantly enhanced extraction yield and protein recovery. The optimal extraction process was a DSR of 1:6 using UAAE at pH 8.5, resulting in a 16% yield and 34% protein recovery. Furthermore, the study found that UAE facilitated the extraction of non-polar/hydrophobic amino acids while AE proved to be efficient in extracting sulfur-containing amino acids. This study, for the first time, revealed the role of UAE and AE in promoting the extraction of different profiles of amino acids. The DPE produced using UAAE contained 65% protein, meeting the WHO/FAO/UNU recommended protein intake for preschool-aged children. Furthermore, the DPE exhibited excellent emulsifying properties and oil-holding capacity comparable to commercial soy protein isolates. Overall, UAAE was identified as a promising approach for producing techno-functional and nutritious protein ingredients from Wolffia. The resulting DPE proved to show great potential for functional plant-based food and feed applications.

Re-circulating indoor vertical farm: Technicalities of an automated duckweed biomass production system and protein feed product quality evaluation

Duckweeds are fast-growing and nutritious plants, which are gaining increased attention in different fields of application. Especially for animal nutrition, alternative protein sources are needed to substitute soybean meal. The current bottleneck is the standardized production of biomass, which yields stable quantities of a defined product quality. To solve this problem, an indoor vertical farm (IVF) for duckweed biomass production was developed. It consists of nine vertically stacked basins with a total production area of 25.5 m2. The nutrient solution, a modified N-medium, re-circulated within the IVF with a maximum flow rate of 10 L min−1. Nutrients were automatically added based on electrical conductivity. In contrast, ammonium was continuously supplied. A water temperature of 23 °C and a light intensity of 105 μmol m−2 s−1 with a photoperiod of 12:12 h were applied. During a 40-day production phase, a total of 35.6 kg of fresh duckweed biomass (equals 2.1 kg of dried product) was harvested from the IVF. On average, 0.9 kg day−1 of fresh biomass was produced. The dried product contained 32% crude protein (CP) and high levels of proteinogenic amino acids (e.g. lysine: 5.42 g, threonine: 3.85 g and leucine: 7.59 g/100 g CP). Biomass of this quality could be used as a protein feed alternative to soybean meal. The described IVF represents a modular model system for duckweed biomass production in a controlled environment and further innovations and upscaling processes.

Use of minute duckweed (Lemna perpusilla) for supplemental feed in catfish (Clarias sp.) culture: determination of the optimal proportion using powersim simulation

Catfish farming is very profitable because the fish is easy to rear and can be harvested quickly. However, the cost of feed as the most significant component in production costs is currently getting higher. The availability and utilization of alternative feed is an urgent solution in creating sustainable catfish farming. This research was carried out during December 2020 – January 2021 in the Research Center for Limnology, Cibinong, Indonesia, which aims to determine the optimal proportion of minute duckweed (Lemna perpusilla) biomass added as feed supplemental to obtain an optimum growth of catfish fingerlings (Clarias sp.). Catfish were reared for 63 days in nine aquariums with a density of 25 fish per aquarium. The commercial pellet given in the control aquarium was 100% pellet portion (5% of the total fish weight), while in the treatment aquariums were 60% and 40% of the total fish weight. As compensation, fresh duckweed (L. perpusilla) was provided ad libitum. Fish were sampled twice to measure their weight and body length. This study showed that the proportion of duckweed as much as 40% as a supplement for commercial pellets could produce optimal catfish growth.

Hematological and antioxidants responses of dairy cow fed with a combination of feed and duckweed (Lemna minor) as a mixture for improving milk biosynthesis

Abstract. Tanuwiria UH, Mushawwir A. 2020. Hematological and antioxidants responses of dairy cows fed with a combination of feed and duckweed (Lemna minor) as a mixture for improving performance. Biodiversitas 21: 4741-4746. A total of twenty-five, 5-7th-lactation-old or 7-8thyears-old dairy cows were used in the current study to study the effect of feed duckweed (Lemna minor) on the hematological status and parameters related antioxidant in the dairy cow. Each group of treatment involved 5 replicates with a dairy cow each (5 dairy cows per group). All of the group was provided ration following F0 = Uncultivated grass (UG) 60% and supplemented concentrated (C) 40%; F1 = UG 50%+fresh duckweed 10%+C 40%; F2 = UG 60%+fresh duckweed 3%+C 37%; F3 = UG 50%+fresh duckweed 10%+dried duckweed 3%+C 37%; F4 = UG 45%+fresh duckweed 15%+dried duckweed 2%+C 38%. Blood samples were collected from each dairy cow monthly beginning at the first month of this experiment, from the tail vein (vena coccygeal), using a sterilized syringe and vacuum tube containing K3EDTA. Hematological parameters were analyzed by a hematology analyzer. The blood samples collected were also centrifuged to separate the plasma. The plasma was used to determine of concentration of parameters related to antioxidant by an automatic biochemical analyzer, using a commercial kit. All procedure of the analysis was following based on the Biolabo kit (Franch) and Randox kit (UK). Based on in this current study showed that increased hematological condition and antioxidants profile in dairy cow supplemented duckweed . Supplemented duckweed can be improved physiological condition (hematologic and antioxidants) in the dairy cow.

Growth and Essential Carotenoid Micronutrients in Lemna gibba as a Function of Growth Light Intensity.

Duckweed is a promising food crop with multiple benefits for space applications. Fresh duckweed could deliver synergistically acting essential antioxidant nutrients to a crew – but only if growth conditions provide the plant with the right cues to trigger antioxidant formation. We grew Lemna gibba under continuous growth light ranging from low to very high intensities (photosynthetic photon flux densities = PPFDs) in order to investigate the effect on plant growth, photosynthesis, and level of carotenoid antioxidants that are essential human micronutrients. Lemna gibba achieved remarkably high growth rates under modest growth PPFD by virtue of superior light absorption resulting from minimal self-shading and high chlorophyll levels. Conversely, L. gibba’s growth rate remained high even under very high growth PPFDs. This notable ability of L. gibba to avoid inactivation of photosynthesis and diminished growth under very high growth PPFDs resulted from a combination of downregulation of chlorophyll synthesis and increased biochemical photoprotection that limited a build-up of excessive excitation energy. This biochemical photoprotection included accumulation of zeaxanthin (an essential human micronutrient) and high levels of zeaxanthin-catalyzed thermal energy dissipation of excess excitation. Compared to the light levels needed to saturate L. gibba photosynthesis and growth, higher light levels were thus required for strong induction of the essential antioxidant zeaxanthin. These results indicate a need for design of light protocols that achieve simultaneous optimization of plant yield, nutritional quality, and light-use efficiency to circumvent the fact that the light requirement to saturate plant growth is lower than that for production of high zeaxanthin levels. How this trade-off between light-use efficiency of growth and nutritional quality might be minimized or circumvented to co-optimize all desired features is discussed.

Mass Production of Lemna minor and Its Amino Acid and Fatty Acid Profiles.

The surface floating duckweed Lemna minor (Lemnaceae) is a potential ingredient to replace the application of fish-meal in the aqua-feed. The culture technique of the duckweed was standardized in outdoor tanks and then applied in the pond. Three consecutive experiments were conducted in tanks (1.2 × 0.35 × 0.3 m). In experiment 1, four different manures were used. In manure 1 (organic manure, OM) and manure 3 (2x OM), cattle manure, poultry droppings, and mustard oil cake (1:1:1) were used; in manure 2 (inorganic fertilizer, IF), urea, potash, triple superphosphate were used; manure 4 (2x OM+IF) was a combination of manure 2 and manure 3. In experiment 2, manure 1 (OM) and manure 2 (IF) were used, and manure 3 (OM+IF) was a combination of both manures. In experiment 3, OM and IF were selected. In pond (20 × 10 × 0.5 m), OM was applied. Fresh duckweed was seeded after 5 days of manure application. In experiments 1 and 3, total production was significantly (P < 0.05) higher in OM compared to other treatments. In experiment 2, there was no significant (P > 0.05) difference in production between OM and IF. In pond, relative growth rate (RGR) of duckweed ranged from 0.422 to 0.073 g/g/day and total production was 702.5 Kg/ha/month (dry weight). Protein, lipid, and ash contents were higher in duckweed cultured in OM compared to IF. The duckweed was a rich source of essential (39.20%), non-essential (53.64%), and non-proteinogenic (7.13%) amino acids. Among essential amino acids, leucine, isoleucine, and valine constituted 48.67%. Glutamic acid was 25.87% of total non-essential amino acids. Citrulline, hydroxiproline, taurine, etc. were found in the duckweed. The fatty acid composition was dominated by PUFA, 60–63% of total fatty acids, largely α-linolenic acid (LNA, 18:3n-3) at around 41 to 47% and linoleic acid (LA, 18:2n-6) at 17–18%. The nutritional value of duckweeds and their production potential in the pond conditions were evaluated. Duckweed biomass may thus be used to replace commercial fish-meal that is currently used in aquaculture.

Water lentils (duckweed) in Jordan irrigation ponds as a natural water bioremediation agent and protein source for broilers

Abstract The growth of wild water lentils (duckweed) in Jordan’s farm irrigation ponds has focused attention on the need to study the functions of these plants as a natural water bioremediation agent and as a potential protein source for broilers. This paper examined the water source and water quality (nutrient composition) of irrigation ponds that support duckweed plants and their suitability as broilers feed. The results showed that the source of the irrigation ponds is Zarqa River, and the analyzed water quality parameters of the source fall within the allowed limits set forth in the Jordanian Standard. The growth of duckweed in farm irrigation ponds reduces the nutrient supply to irrigated crops and serves as a purifier of irrigation water. These plants remove an average of 20% Ca, 33% Mg, 21% K, 13% Cl, 25% SO4, 35% PO4, 1.5% Na, and 40% NO3. Fresh duckweed contains approximately 94% water and 6% dry matter; the average nutrient concentrations in dry matter are 26% protein, 4.16 % N, 5.2% fiber, 3.1% fat, 0.86% P, 2.4% K, 4.3% Ca, 0.88% Mg, 0.2% Fe, 1.62% Cl, 0.16% Na, 0.008% Zn, 0.07% Mn and 0.002% Cu. This research reveals the potential for Jordan to examine the availability of duckweed in farm irrigation ponds and their function as water bioremediation agents and their suitability as a protein and nutrient source for broilers. If harvested at frequent intervals and dried, water lentil plant (duckweed) could be of great benefit to Jordan's livestock sector, especially with regard to poultry, where feedstuffs are limited in supply and prices are typically high.

Feeding Diets Containing Different Forms of Duckweed on Productive Performance and Egg Quality of Ducks

The present experiment was undertaken to study the feeding effect of diets containing different forms of duckweed for local ducks on their productive performance and egg quality or egg yolk pigmentation. A total of 90 birds of 24 wk old ducks were randomly divided into 18 experimental units of 2.0 x 1.0 m2 of cages. The experiment was assigned in a completely randomized design (3 treatments with 6 replicates, 5 birds each). There were 3 dietary treatments, namely P1= ducks fed a complete diet containing 20 % of dried duckweed and given in the form of dry-mash; P2= a complete diet in P1 but it was offered in wet form (slurry); and P3= ducks were offered basal diet in the form of dry-mash and fresh duckweed was offered separately ad libitum. Diets were formulated to have similar nutritional contents. Feed consumption, feed conversion ratio (FCR), and egg yolk pigmentation were measured. The result of the study showed that these three parameters were affected by the feeding different forms of duckweed. Feeding diet with fresh duckweed brought about the best pigmentation than did the dry one. Fresh duckweed offers a promise as a potential feedstuff for ducks and has a good implication in reducing feed processing cost.

Functional, Physiochemical, and Rheological Properties of Duckweed (Spirodela polyrhiza) Protein

Duckweed contains mainly starch and protein, and protein is a coproduct of starch-based biofuel production. Plant proteins have a great potential for value-added products. However, the lack of information on duckweed protein as a bioenergy coproduct limits its use. In this study, duckweed protein was extracted, purified, and characterized for chemical composition, molecular weight, surface hydrophobicity, emulsion, thermal stability, and rheological properties. Duckweed (Spirodela polyrhiza) with an initial protein content of 34.5% was selected for this study, and the protein was extracted from fresh, frozen, and ambient temperature dried duckweed. The highest extraction rate (52.1%) was obtained from fresh duckweed, followed by ambient-dried duckweed (45.6%) and frozen duckweed (44.3%). The protein samples extracted from ambient-dried duckweed had the highest purity (67.8%) of the three prepared duckweed sources. Duckweed protein showed a low stability of the emulsion and poor emulsifying properties. Molecular weights of duckweed protein fractions ranged from 14 kDa to more than 160 kDa. FTIR showed five distinct absorption bands related to amide A and B, amide I and II, and the carbohydrate component. The melting peak of the duckweed protein sample was broad; it began below 50C, covered a range of about 120C, ended at 160C, and degraded at 250C. Duckweed protein is more hydrophobic than soy proteins at the same pH value, which suggests that duckweed protein has potential to improve water resistance of protein-based adhesives.

Expression and characterization of Acidothermus cellulolyticus E1 endoglucanase in transgenic duckweed Lemna minor 8627

Endoglucanase E1 from Acidothermus cellulolyticus was expressed cytosolically under control of the cauliflower mosaic virus 35S promoter in transgenic duckweed, Lemna minor 8627 without any obvious observable phenotypic effects on morphology or rate of growth. The recombinant enzyme co-migrated with the purified catalytic domain fraction of the native E1 protein on western blot analysis, revealing that the cellulose-binding domain was cleaved near or in the linker region. The duckweed-expressed enzyme was biologically active and the expression level was up to 0.24% of total soluble protein. The endoglucanase activity with carboxymethylcellulose averaged 0.2 units mg protein −1 extracted from fresh duckweed. The optimal temperature and pH for E1 enzyme activity were about 80 °C and pH 5, respectively. While extraction with HEPES ( N-[2-hydroxyethyl]piperazine- N′-[2-ethanesulfonic acid]) buffer (pH 8) resulted in the highest recovery of total soluble proteins and E1 enzyme, extraction with citrate buffer (pH 4.8) at 65 °C enriched relative amounts of E1 enzyme in the extract. This study demonstrates that duckweed may offer new options for the expression of cellulolytic enzymes in transgenic plants.

Comparison of faecal collection method with high- and low-quality diets regarding digestibility and faeces characteristics measurements in Nile tilapia

The need for unbiased digestibility estimation has led to the development of a number of faeces collection methods. However, there is still a large variation in apparent digestibility coefficient (ADC) of diet/ingredients between these methods. This study investigated the impact of dietary quality on ADC and faeces recovery measurements obtained by two faecal collection methods (Choubert and settling tank). The fish were fed five diets: a control diet as high-quality diet, two levels of dried duckweed (20% and 40%) and two levels of fresh duckweed (20% and 40%), which were added to the control diet, as low-quality diets. Apparent digestibility coefficient estimates were highly correlated (r>0.95) between both faecal collection methods. For all diets the ADC estimates were higher when using settling tanks compared with Choubert collectors. For the control diet differences in ADC between two collectors were small, but by inclusion of duckweed these differences increased. The recovery percentage of faeces was not correlated between both faecal collection methods (r=0.22, P=0.41). The estimated recovery percentage of faeces by settling tanks was about three times higher than by Choubert. In conclusion, the differences in ADC and faeces recovery measured by two faecal collection methods depend on diet quality

Microbial quality of tilapia reared in fecal-contaminated ponds*1

The microbial quality of tilapia reared in four fecal-contaminated fishponds was investigated. One of the fishponds (TDP) received treated sewage with an average fecal coliform count of 4×103 cfu/100 mL, and feed of fresh duckweed grown on treated sewage was used. The number of fecal coliform bacteria attached to duckweed biomass ranged between 4.1×102 and 1.6×104 cfu/g fresh weight. The second fishpond (TWP) received treated sewage, and the feed used was wheat bran. The third fishpond (FDP) received freshwater, and the feed used was the same duckweed. Pond 4 (SSP) received only settled sewage with an average fecal coliform count of 2.1×108/100 mL. The average counts in the fishponds were 2.2×103, 1.7×103, 1.7×102, and 9.4×103 cfu/100 mL in TDP, TWP, FDP, and SSP, respectively. FDP had a significantly (P<0.05) lower fecal coliform count than the treated sewage-fed ponds and SSP. The microbial quality of the tilapia indicated that all tissue samples except muscle tissues were contaminated with fecal coliform. Ranking of the fecal coliform contamination levels showed a decrease in the order intestine>gills>skin>liver. Poor water quality (ammonia and nitrite) in SSP resulted in statistically higher fecal coliform numbers in fish organs of about 1 log10 than in treatments with good water quality. Pretreatment of sewage is therefore recommended.

Apparent digestibility coefficient of duckweed (Lemna minor), fresh and dry for Nile tilapia (Oreochromis niloticus L.)

Dry matter (DMD), protein (PD), ash (AD), fat (FD), gross energy (ED) and phosphorus (PhD) digestibility coefficients were determined for five different iso-N fish diets fed to Nile tilapia (Oreochromis niloticus). The control diet contained fishmeal (35%), corn (29%), wheat (20%), wheat bran (10%), fish oil (3%), diamol (2%) and premix (1%). Partial replacement of dry matter of fishmeal, corn grain, wheat grain, wheat bran and fish oil by 20% and 40% of dry matter of duckweed, in a dry and fresh form, was performed. Diets of treatments 1 and 2 included 20% and 40% of duckweed, respectively, in a dry form. In treatments 3 and 4, tilapia received formulated diets 4 and 5 in addition to 20% and 40% fresh duckweed providing the same amount of dry matter and protein as in control. The specific growth rates (SGRs) of tilapia were 1.51±0.07, 1.38±0.03, 1.31±0.06, 1.44±0.02 and 1.33±0.05, in control and treatments 1–4. There was no significant difference between SGR for the control diet and the diet with 20% fresh duckweed, while the other treatment groups had significantly lower SGR. All the treatment diets provide good values for feed conversion ratios (FCRs) and protein efficiency ratio (PER). Dry matter of diets ranged from 61.8% in treatment 4 to 85.2% in control. All the diets have high PD (88.4–93.9%) and high-energy digestibility (78.1–90.7%). Dry matter of duckweed were 66.8, 63.3, 45.8 and 28.3 in treatments 1 to 4 respectively. Protein values were 78.4, 79.9, 77.6 and 75.9, while ED values were 59.8, 60.9, 64.5 and 58.4 in treatments 1 to 4 respectively. Analysis of body composition shows that tilapia fed diets with duckweed contain significantly (P<0.05) higher phosphorus and protein content and significantly (P<0.05) lower lipid content. In contrast, tilapia fed control diet had a significant higher (P<0.05) dry matter content and lower ash content.

Microbial quality of tilapia reared in fecal-contaminated ponds

The microbial quality of tilapia reared in four fecal-contaminated fishponds was investigated. One of the fishponds (TDP) received treated sewage with an average fecal coliform count of 4×10 3 cfu/100 mL, and feed of fresh duckweed grown on treated sewage was used. The number of fecal coliform bacteria attached to duckweed biomass ranged between 4.1×10 2 and 1.6×10 4 cfu/g fresh weight. The second fishpond (TWP) received treated sewage, and the feed used was wheat bran. The third fishpond (FDP) received freshwater, and the feed used was the same duckweed. Pond 4 (SSP) received only settled sewage with an average fecal coliform count of 2.1×10 8/100 mL. The average counts in the fishponds were 2.2×10 3, 1.7×10 3, 1.7×10 2, and 9.4×10 3 cfu/100 mL in TDP, TWP, FDP, and SSP, respectively. FDP had a significantly ( P<0.05) lower fecal coliform count than the treated sewage-fed ponds and SSP. The microbial quality of the tilapia indicated that all tissue samples except muscle tissues were contaminated with fecal coliform. Ranking of the fecal coliform contamination levels showed a decrease in the order intestine>gills>skin>liver. Poor water quality (ammonia and nitrite) in SSP resulted in statistically higher fecal coliform numbers in fish organs of about 1 log 10 than in treatments with good water quality. Pretreatment of sewage is therefore recommended.

Chronic ammonia toxicity to duckweed-fed tilapia ( Oreochromis niloticus)

The effects of prolonged exposure to sub-lethal un-ionised ammonia nitrogen (UIA-N) concentrations on the growth performance of juvenile Nile tilapia ( Oreochromis niloticus) fed on fresh duckweed ( Lemna gibba) grown on pretreated domestic sewage have been investigated. The experiment was conducted over 75 days using juveniles with a mean body weight of 20 g. Five nominal, total ammonia nitrogen concentrations (control, 2.5, 5, 7.5 and 10 mg N l −1) were established as treatment groups. Statistical analysis of the specific growth rate (SGR) showed no significant ( p>0.05) differences between the SGR (0.71) of tilapia in the control (0.004 mg UIA-N l −1) and the SGR (0.67) of those exposed to 0.068 mg UIA-N l −1. The SGR of tilapia exposed to un-ionised ammonia nitrogen over 0.068 mg UIA-N l −1 (0.144, 0.262 and 0.434 mg UIA-N l −1) was significantly reduced ( p<0.01). The no-observable effect concentration was 0.068 mg UIA-N l −1, while the lowest observable effect concentration was 0.144 mg UIA-N l −1. Increasing the un-ionised ammonia concentration increased the feed conversion ratio (FCR). At 0.144 mg UIA-N l −1, the FCR increased by a factor 1.6 of the value observed in the control, while at 0.262 mg UIA-N l −1 the FCR increased by a factor of 2.7. At 0.434 mg UIA-N l −1, the FCR increased by a factor of 4.3. Protein efficiency ratio (PER) was also negatively correlated with the un-ionised ammonia concentration above 0.068 mg UIA-N l −1. This study concluded that, for raising Nile tilapia in fishponds fed on fresh duckweed or other feed, the toxic level of UIA-N and its negative effect on the growth performance lies between 0.07 and 0.14 mg UIA-N l −1. It is recommended that the UIA-N concentration be maintained below 0.1 mg l −1.

Use of Duckweed as a Protein Supplement for Breeding Ducks

An experiment was conducted at the experimental duck farm of Cantho University to determine the effects of feeding duckweed (Lemna minor) that replaced commercial protein supplements in diets for local and Cherry Valley breeding ducks. The experiment included a total of 180 ducks, with five treatments and three replicates and six breeding ducks (one male plus five females together) per replicate, for both local and exotic Cherry Valley ducks. The five diets were fed ad libitum and were based on rice byproducts supplemented with roasted soya bean meal plus dried fishmeal at levels of 100% (SF100, control), 75 (SF75), 50 (SF50), 25 (SF25) or zero (SF0) % of the protein in the control diet, corresponding to 18, 15, 13, 10 and 8% CP in the diets for both breeds, respectively. Fresh duckweed was supplied ad libitum for all treatments. These diets were fed to local breeding ducks from 7 to 12 months of age, and to exotic breeding ducks (Cherry Valley) from 8 to 13 months of age. Total mean daily dry matter (DM) intakes were 183, 178, 176, 177 and 174 g (p<0.05) for the local ducks, and 221, 208, 215, 219 and 210 g (p<0.01) for the exotic ducks for the SF100 (control), SF75, SF50, SF25 and SF0 diets, respectively. Laying rates of the local ducks were 66.5, 65.2, 62.9, 63.1 and 62.3%, and of the Cherry Valley ducks 61.9, 58.4, 58.9, 59.1 and 53.5% (p<0.001) for the control (SF100), SF75, SF50, SF25 and SF0 treatments, respectively. Fertile egg rates were 95.6, 95.6, 97.8, 97.8 and 92.2%, and hatchabilities 89.4, 80.6, 87.2, 88.6 and 77.8% (p<0.05) for the local breed, and 97.8, 97.8, 91.1, 92.2 and 90.0% (p<0.05) and 72.8, 74.7, 75.0, 74.3 and 76.7% for the Cherry Valley ducks for diets SF100, SF75, SF50, SF25 and SF0, respectively. Corresponding feed conversion ratios (dry matter basis) were 3.83, 3.82, 3.89, 4.01 and 3.96 kg feed per kg egg mass for the local ducks and 4.52, 4.56, 4.58, 4.73 and 5.02 kg feed per kg egg mass for the Cherry Valley ducks for the SF100, SF75, SF50, SF25 and SF0 treatments, respectively. Replacement of 100% of the protein supplement by fresh duckweed in the diets of the local laying ducks decreased the feed costs by 25% compared to the control diet.

Use of Duckweed as a Protein Supplement for Growing Ducks

An experiment was conducted at the experimental duck farm of Cantho University to determine the effects of feeding duckweed (Lemna minor) that replaced commercial protein supplements in diets for local and Cherry Valley breeding ducks. The experiment included a total of 180 ducks, with five treatments and three replicates and six breeding ducks (one male plus five females together) per replicate, for both local and exotic Cherry Valley ducks. The five diets were fed ad libitum and were based on rice byproducts supplemented with roasted soya bean meal plus dried fishmeal at levels of 100% (SF100, control), 75 (SF75), 50 (SF50), 25 (SF25) or zero (SF0) % of the protein in the control diet, corresponding to 18, 15, 13, 10 and 8% CP in the diets for both breeds, respectively. Fresh duckweed was supplied ad libitum for all treatments. These diets were fed to local breeding ducks from 7 to 12 months of age, and to exotic breeding ducks (Cherry Valley) from 8 to 13 months of age. Total mean daily dry matter (DM) intakes were 183, 178, 176, 177 and 174 g (p<0.05) for the local ducks, and 221, 208, 215, 219 and 210 g (p<0.01) for the exotic ducks for the SF100 (control), SF75, SF50, SF25 and SF0 diets, respectively. Laying rates of the local ducks were 66.5, 65.2, 62.9, 63.1 and 62.3%, and of the Cherry Valley ducks 61.9, 58.4, 58.9, 59.1 and 53.5% (p<0.001) for the control (SF100), SF75, SF50, SF25 and SF0 treatments, respectively. Fertile egg rates were 95.6, 95.6, 97.8, 97.8 and 92.2%, and hatchabilities 89.4, 80.6, 87.2, 88.6 and 77.8% (p<0.05) for the local breed, and 97.8, 97.8, 91.1, 92.2 and 90.0% (p<0.05) and 72.8, 74.7, 75.0, 74.3 and 76.7% for the Cherry Valley ducks for diets SF100, SF75, SF50, SF25 and SF0, respectively. Corresponding feed conversion ratios (dry matter basis) were 3.83, 3.82, 3.89, 4.01 and 3.96 kg feed per kg egg mass for the local ducks and 4.52, 4.56, 4.58, 4.73 and 5.02 kg feed per kg egg mass for the Cherry Valley ducks for the SF100, SF75, SF50, SF25 and SF0 treatments, respectively. Replacement of 100% of the protein supplement by fresh duckweed in the diets of the local laying ducks decreased the feed costs by 25% compared to the control diet.

Composition and nutritive value of sewage-grown duckweed ( Lemna minor L.) for rats

Gross composition and carotenoid and heavy metal content of sewage-grown duckweed were analysed. The essential amino acid pattern of its protein was also determined. The dry matter content in fresh duckweed when harvested ranged from 78 to 95 g per kg. Gross composition of duckweed grown at the sewage inlet and water outlet did not differ markedly but the former contained about 30% more carotenoid. The protein content of both samples exceeded 300 g per kg (dry matter basis). This protein was high in lysine but low in sulphur amino acids. The metal (zinc, copper, lead and cadmium) content was below harmful levels. The nutritive value of protein of duckweed grown at the sewage inlet, determined on rats using the Thomas-Mitchell balance method, was higher (33) than when grown at the water outlet (25). The true digestibility of both proteins was relatively low (60% and 51%, respectively).

Evaluation of duckweed ( Lemna perpusilla and Spirodela polyrrhiza) as feed for Nile tilapia ( Oreochromis niloticus)

Two 70-day experiments were conducted in outdoor 5 − m 2 static-water concrete tanks to determine the nutritional value of fresh duckweed ( Lemna perpusilla and Spirodela polyrrhiza) as feed for Nile tilapia ( Oreochromis niloticus). Lemna and Spirodela were compared in Experiment 1 at daily feeding rates of 2.5, 5.0 and 7.5% of total fish body weight on a duckweed-dry-weight basis. As Lemna was a more suitable feed for tilapia on the basis of growth rate and feed utilization efficiency, optimal daily feeding rates of Lemna were determined in Experiment 2 by feeding at rates from 1 to 6% of the total fish body weight on a duckweed-dry-weight basis. The optimal daily feeding rates of Lemna were 5, 4 and 3% of the total fish body weight on a duckweed-dry-weight basis for fish of 25 to 44 g, 45 to 74 g and 75 to 105 g in weight, respectively.