ISSN Original Article GROWTH PERFORMANCE OF OREOCHROMIS NILOTICUS FED DUCKWEED (LEMNA MINOR) BASED DIETS IN OUTDOOR HAPAS

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1 Available online at International Journal of Research in Fisheries and Aquaculture Universal Research Publications. All rights reserved ISSN Original Article GROWTH PERFORMANCE OF OREOCHROMIS NILOTICUS FED DUCKWEED (LEMNA MINOR) BASED DIETS IN OUTDOOR HAPAS SOLOMON S.G. AND OKOMODA V.T. Department of Fisheries and Aquaculture, University of Agriculture Makurdi, Nigeria *Tel: , 2 Received 17 October 2012; accepted 02 December 2012 Abstract This study was designed to evaluate the growth performance of Tilapia, (Oreochromis niloticus) fed diets with various inclusion levels of Duckweed (Lemna minor). Five isonitrogenous (20% CP) diets containing 5%, 10%, 15%, 20% and 25% of Duckweed representing diets 1 to 5 respectively were prepared. The fish were fed 5% of their body weight for 56 days. O. niloticus fingerlings with mean initial weight (MIW) of 1.45g±0.00was used for the experiment and the fingerlings were procured from a homogenous source through natural breeding. The result showed that fish fed 5% Duckweed inclusion (diet 1) gave the best value for mean weight gain (MWG = 1.92g±0.001), specific growth rate (SGR = 1.41±0.01), Food Conversion Ratio (FCR = 1.94±0.01) and Apparent Net Protein Utilization (ANPU = 57.47±1.24). Fish fed Diet 2 (10% Duckweed) however followed closely with MWG of 1.85g±0.00; FCR 2.37±0.00 and ANPU ± This trend of decrease however continued till Diet 5 suggesting that as Duckweed inclusion increases, MWG, SGR, PER and ANPU decreases across the five treatments while FCR increased. 5% level of inclusion of Duck weed is advised for inclusion in the Diet of O. niloticus 2012 Universal Research Publications. All rights reserved Keywords: Anti-nutritional factor, Duck weed, Unconventional feedstuffs. INTRODUCTION Feeding constitute a major factor in intensive rearing of fin fishes and their fry. This is because growth of fish depends strongly on the quality of feeds provided. Depending on the culture system adopted, feed can represent 40 to 70% of the total production costs (1). Fishmeal is the major source of protein for farmed fish worldwide and is in limited supply (2). However, nearly all researchers agree that an alternative ingredient should be used in the aquafeed industry in place of fish meal, whose supplies are limited although demand for it is expected to rise. For this reason, many studies have been conducted on the replacement of expensive animal proteins with lower cost ingredients. Considerable attention has been devoted to the replacement of fish meal with plant protein sources such as soybean meal (3, 4), mucuna seed meal (5, 6), winged bean (7), and various legumes (8, 9). The macrophytes of the Lemnaceae family, known as duckweeds, are the smallest flowering plants in the world. With a high protein content and fairly full spectrum of amino acids, duckweed would appear to have the capacity to replace expensive fish and soya bean meal in aquaculture diet formulations. Duckweed, as a natural protein source, has a better array of essential amino acids than most other vegetable proteins and more closely resembles animal protein (10). Newly harvested duckweed plants contain up to 18-43% protein by dry weight and can be used without further processing as a complete feed for fish. Compared with most other plants, duckweed leaves contain little fiber and little to no indigestible material even for monogastric animals (11). This contrasts with the compositions of many crops such as soy beans, rice, and maize, approximately 50% of whose biomass comprises residues high in fiber and low in digestibility. Duckweed meal has been used for cattle, poultry, swine and fish feeding, showing favorable results (12). Due to the omnivorous feeding habit of tilapia which enable them tolerate the inclusion of plant protein sources in their diet, and thus reducing feed expenses, the present study was therefore designed to formulate cost effective fish feed using locally available fish feed of plant origin to replace fish meal and to explore the nutritive potential of 61

2 this non-conventional plant sources as well as study the growth efficient of Oreochromis niloticus fed duckweed based diets. MATERIALS AND METHODS Processing of Feedstuffs Duckweed was harvested from an earthen Pond (30m x 30m x 1.5m) in the month of July in Makurdi, Nigeria. The duckweed was then sundried, milled and packaged for use. The soybean grains was cleaned, sundried toasted in an oven at 100 o C for 15 minutes until the grain cracked. It was then dehulled, Milled and Packaged for use. Maize was cleaned, milled and packaged for use. The mineral and vitamin premix used was purchased from Agro based shop in Makurdi, Nigeria. Feed Formulation and Compounding Pearson square method was used to formulate five isonitrogenous (20% crude protein) diets for this experiment. Vitamin and mineral premix was fixed at 5% for the five diets while duckweed inclusion in the five diets (Dt1 Dt5) was at 5%, 10%, 15%, 20% and 25% respectively. The Aggregate ingredients for each diet were then weighed using a Digital weighing balance. The mixture was dry mixed and water added at 60 o C to form a tough dough which was then pelleted through a 3mm dice. The pellets were collected in trays, sundried (Average air temperature-29 o C±0.05, humidity-45%,wind speed-9kmh -1 ) and packaged for use. EXPERIMENTAL SET UP The feeding trial was conducted in an earthen pond measuring 25m x 25m x 1.5m using 20 Hapas of 1 x 1 x 1m 3. Oreochnomis niloticus used for the experiment was gotten from a homogenous source from the Fish Hatchery of University of Agriculture, Makurdi Nigeria. The fingerlings were acclimatized for one week after which they were sorted to the hapas i.e 20 fingerlings per hapa. Each treatment was triplicated and fish were fed 5% of body weight. The fish were weighed weekly and weight of feed adjusted as appropriate. Before commencement of the experiment some experimental fish were sacrificed to determine the carcass proximate composition. The same thing was done at the end of experiment using the method of AOAC (13). Also the proximate analysis of the experimental diets was also carried out. The experiment lasted for 56 days. The Growth parameter measured includes. SGR = L n W 2 Ln W T Where W 2 = Final wt of Fish W 1 = Initial wt of fish T = Duration of the experiment in days Ln = natural logarithms (ii) Food Conversion Ration (FCR): FCR was calculated as follows FCR = Wt of wt. gain 62 feed fed (iii) Protein Efficiency Ratio (PER) Wt gain PER = Pr otein fed (iv) Apparent Net Protein Utilization (ANPU) ANPU = 100 x Carcass Pr otein gain Pr otein fed Protein Gain = Final Body Protein protein. - Initial body Table 1: Inclusion Levels of Various Feedstuffs ansd their proximate Composition DIETS Diet 1 Diet 2 Diet 3 Diet 4 Diet 5 Soybean Maize Duckweed Meal PROXIMATE COMPOSITION OF DIETS AND DUCKWEED Diet 1 Diet 2 Diet 3 Diet 4 Diet 5 Moisture Crude Protein Ether Extract Ash Crude Fibre NFE Duckweed H 2 O = 14.6 CP = 17.60% EE = 1.70% Ash=24.05% CP=35.45 CP = Crude Protein; EE = Ether Extract; CF = Crude Fibre RESULT Table 1 show the inclusion levels of the various feedstuffs obtained from formulation using Pearson square method, also on table 1 the result of proximate analysis of the five experimental diets is shown. Duckweed meal was fixed at 5%, 10%, 15%, 20% and 25% in diets 1-5 respectively. While mineral and vitamin were equally fixed at 2.5% each for the five diets. In table 1 crude protein value obtained from biochemical analysis showed that the value ranged from Table 2 shows the parameters for assessment of growth response by O. niloticus to the experiment diets. The result showed that mean initial weight (MIW) and mean final weight (MFW) values were not statistically significant in the five diets (P>0.05). However the highest mean weight gain (MWG) value of 1.92g was obtained from diet 1 which has the least percentage inclusion of Duckweed meal of 5% - the least MWG value of 1.56 was obtained for diet 5 (25% Duckweed inclusion). The MWG value was statistically significant in the five diets (P < 0.05).

3 Table 2: Parameters for Assessment of Growth Response of Oreochromis niloticus to the experimental diets DIETS AND PERCENTAGE OF DUCKWEED INCLUSION 5% 10% 15% 20% 25% Parameter Diet 1 Diet 2 Diet 3 Diet 4 Diet 5 MIW (g) ± ± ± 0.11 MFW (g) 3.37 ± 0.10 a 3.31 ± a 3.22 ± b ± b ± c MWG (g) 1.92 ± a ± 0.01 a 1.76 ± 0.02 b 1.63 ±0.006 c 1.56 ± 0.01 c SGR ± 0.01 a ± c ± b ± d 0.65 ± 0.00 e FCR 1.94 ± 0.10 d 2.37 ± c ± b 6.29 ± 0.00 a 6.29 ± 0.00 a PER ± 0.00 a ± b ± c ±0.05 d ± e ANPU ± 1.24 b ± a ± 0.51 b ± 0.52 c ± 0.68 c Values on the same row carrying the same superscripts are not statistically significant (P > 0.05) MIW = Mean Initial wt, FCR = Feed Conversion Ratio, SGR = Specific Growth Rate, MFW= Mean Final Wt, PER = Protein Efficiency Ratio, MWG = Mean Weight Gain ANPU = Apparent Net Protein Utilization Table 3 Proximate Analysis of the Carcass of O. niloticus Before and after the Experiment. Before Diet 1 Diet 2 Diet 3 Diet 4 Diet 5 Crude Protein (%) a c b a c Ash (%) Moisture (%) Ether Extract (%) Crude Fibre (%) NFE Nutrient utilization by the experiment fish was assessed by calculating the Specific Growth Rate (SGR), Feed Conversion Ratio (FCR), Protein Efficiency Ratio (PER) and Apparent Net Protein Utilization (ANPU). From table 2 the SGR value shows that Diet 1 with FCR value of 1.94 was the best while the poorest value of FCR was obtained for Diet 5. (6.29). ANPU value of obtained for Diet 1 was the best while Diet 5 was the poorest for the same parameter. MWG, SGR, FCR, PER and ANPU values decrease as duckweed meal inclusion increases. Table 3 shows the proximate Analysis of the carcass of O. niloticus fed the five diets. There was increase in body protein, Ash, Ether extract and crude fibre, while moisture content values reduced compared to the start of the experiment. DISCUSSION The protein content of duckweed Lemna minor in this study was analyzed to be 17.60% while crude fibre was estimated to be Similarly Erdal et al (14) reported 18.38% CP for Lemna minor. Flavia, et al (15), reported a crude protein and fiber content of 38.03% and 16.17% respectively of for dried duckweed (Lemna valdiviana), the proximate composition of four different species of duckweed was determined by Rusoff et al (16) and reported CP of 25.2%, CF of 9.4% for Lemna gibba, CP of 28.7%, CF of 9.2% for Spirodella punctate; CP of 29.1%, CF of 8.8% Spirodella polyrhiza and CP of 36.5%, CF of 11% for Wolffia Columbiana. The difference between the result of the present study and those of these referenced authors is likely due to differences in the Duckweed species as well as nutrient availability of the area where they are cultured. In line with this claim Gijzen and Khondker (17), reported that the protein content of duckweed ranged from 30 to 40%, and the fiber content from 5 to 15%, when the duckweed are cultivated in a nutrient rich media. The present study showed that Duckweed inclusion at 5% had the best growth and as the level of inclusion increased reduced growth of O. niloticus, was observed from 10% up to 30%. Also, the Specific Growth Rate (SGR); Protein Efficiency Ratio (PER) and Apparent Net Protein Utilization (ANPU) values obtained in this study showed similar trend with the MWG. These growth parameters showed that as the inclusions level of Duckweed meal increased these growth parameters measured decreased while Food Conversion Ratio (FCR) in contrast increased as the level of inclusion of duckweed increased, the increase in fibre content as well as anti-nutritional factor in poor quality duckweed may be responsible for this reduced growth observed. Similar to the result of the present study Hassan and Edwards (18) used duckweed of relatively poor quality (23% CP), and cited reduced growth as level of inclusion increased as well as mortality rates in excess of 80% at the highest feeding rates. In contrast to this Fasakin et al (19) used better quality material (cited 50% CP) and recorded improved growth with no significant increase in mortality, compared to the control group, even with 100% substitution. Refstie and Storebakken (2) have cited the sensitivity of fish to such factors as non-starch polysaccharides and phytates, and it may be that as the protein component of duckweed material decreases, the exposure per unit dry matter to these anti-nutritional elements in the feed increase and thus elicit negative growth responses. Though mortality was not recorded in the present study despite using poorer quality duckweed 63

4 compared to those used in Hassan and Edwards (18) experiment, difference in the species of the Fish and duckweed used may be the course of variance in the observation of the two studies. Hassan and Edwards (18) also, reported feed conversion ratio for tilapia fed on fresh duckweed to range from 1.6 to 3.3, which was different from those observed in the present study as feed conversion ratio ranged from 1.94 to According to Lim (20), tilapia activity and feeding becomes reduced when the water temperature is below 20ºC, and feeding stops around 16ºC. However since the present study was performed in a tropical climate and those of Hassan and Edwards s (18) experiment was performed in a temperate climate based on Lim s (20) experiment one would expect a reverse of the value obtained in this present result and those of Hassan and Edwards (18), however the unconformity of the present study findings to Lim s hypothesis may be based on different level of protein in the experimental diet, other dietary inclusions and ingredients as well as processing method of various feed stuff used. In contrast to the result of the present study, Erdal et al (14) reported that Growth performances of Cyprinus capio fed diets containing up to 20% duckweed were comparable to that of the fish fed the control diet, except for 15% duckweed group, and suggested that the lower growth recorded was probably not caused by dietary inclusion of duckweed, but may rather have resulted from some effects of initial handling during the weighing and daily management routines in the experimental system, however since the present study was performed on a different experimental fish as well as different experimental condition, the difference in this result may be attributed to differences in tolerance variability to fiber and anti-nutrient among fish species. The study has shown that the use of this unconventional feed ingredient is capable of supporting growth of farmed Tilapia at low level of inclusion, more so exploitation of Duckweed in aquatic environment can help clear the pathway for navigation purposes and as well provide cheap source of ingredient for making aquaculture feeds. However, in view of tolerance of Tilapia to fibre and cellulose, it is not likely that carnivorous fishes will respond as well to duckweed based diets. References 1. Kubitza, F. (2000). Tilápia: tecnologia e planejamento na produção comercial. Acqua & Imagem, Jundiaí, Brasil, 285pp. 2. Refstie, S. and T. Storebakken. (2001). Vegetable protein sources for Carnivorous fish: potential and challenges. Recent Advances in Animal Nutrition in Australia.13: Solomon, S.G; Tiamiyu, L.O. and Apeh, A. (2004). Effect of Totally replacing Fishmeal by Soybean meal with various percentage leves of L-methionine supplement in the Diets of Tilapia (Oreochromis niloticus). Journal of Sustainable Tropical Agricultural Research 11:6-10. Published by Treasure Publishers, Nigeria, Uyo. ISSN X 4. Tiamiyu, L.O; Solomon S.G. and Oketa, E.J. (2006) Effects of different Boiling periods of Soybean (Glycine max (L) Merril) on Growth performance of Tilapia (Oreochromis niloticus fingerlings. Journal of Aquatic Sciences 21 (1) Published by Nigerian Association for Aquatic Science. ISSN Siddhuraju, P. and Becker, K. (2001). Preliminary nutritional evaluation of Mucuna seed meal (Mucuna pruriens var. utilis) in common carp (Cyprinus carpio L.): an assessment by growth performance and feed utilization. Aquaculture, 196: Tiamiyu, L.O; Solomon, S.G. and Sham, R.A. (2011). Accepted: Growth and Nutrient Utilization of Clarias gariepinus fed hydrothermally processed velvet beans (Mucuna utilis) meals In. International Journal of Agriculture. (Accepted on 16 th August, 2011). Published in press by the African University press in Ghana. 7. Fagbenro, O.A. (1999). 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The World Bank, Washington D.C., USA, 76pp. 13. AOAC (Association of Official Analytical Chemists) (2000); Official method of analysis 16 th edition, Arlinton Virginia. 14. Erdal Y., Ihsan A., and Gökhan G. (2004) Use of Duckweed, Lemna minor, as a Protein Feedstuff in Practical Diets for Common Carp, Cyprinus carpio, FryTurkish Journal of Fisheries and Aquatic Sciences 4: Flávia de A. T.; João B. R.; Rodrigues Débora M. F.; Juan E. and Rodrigo R. (2008). Dried duckweed and commercial feed promote adequate growth performance of tilapia fingerlings Biotemas, 21 (3): 91-97, setembro de ISSN Rusoff, L. L., E. W. Blakney and D. D. Culley. (1980). Duckweeds (Lemnacae Family): A Potential Source of Protein and Amino Acids. J. Agric. Food Chem. 28: Gijzen, H. J.; Khondker, M. (1997). An overview of the ecology, physiology, cultivation and applications of duckweed. Inception Report. Annex 1. Literature Review. Duckweed Research Project (DWRP), Dhaka, 64

5 Bangladesh, 53pp. 18. Hassan, M. S.; Edwards, P. (1992). Evaluation of duckweed (L. Perpusilla and Spirodela polyrriza) as feed for Nile tilapia (Oreochromis niloticus). Aquaculture, 104: Fasakin, E. A.; Balogun, A. M.; Fasaru, B. E. (1999). Use of duckweed, Spirodela polyrriza, L. Schleiden, as a protein feedstuff in practical diets for tilapia, Oreochromis niloticus L. Aquaculture Research, 30: Lim, C. (1989). Practical Feeding Tilápias. In: Lovell, T. (ed.). Nutrition and Feeding of fish. Van Nostrand, Reinhold, New York, USA, 163pp. Source of support: Nil; Conflict of interest: None declared 65