1 Introduction

Fish is considered as the cheapest source of protein available for human (Tidwell and Allan, 2001). Traditionally, animal protein sources, particularly fishmeal are used as the major ingredients of aqua feeds (Glencross et al., 2007). Therefore for reducing fishmeal inclusion levels many plant like products have been suggested as an alternative to fish meal (Caruso, 2015). Continuous efforts are being made by the nutritionist to reduce the feed cost as a strategy to sustainable aquaculture. Finding alternative protein sources to replace fish meal in fish feed is important if the growth of the aquaculture industry is to be sustained (Francis et al., 2001).

The increasing demand of fish meal from the expanding global aquaculture industry and other terrestrial seafood and meal producers, coupled with unstable supply, has inflated the price of the fish meal, making it crucial to look for alternative sustainable aquacultural feed ingredients that are locally available with equivalent nutritional value (Hardy, 2010; Tacon et al., 2011).

Seaweeds are excellent dietary sources of vitamins, proteins, carbohydrates, trace minerals and other bioactive compounds (Kumar et al., 2008). Due to their low contents in lipid, high concentration in polysaccharides, natural richness in minerals, polyunsaturated fatty acids and vitamins as well as their content in bioactive molecules, marine algae are known to be a good source of healthy food. In aquatic animals, seaweeds have been used as a dietary supplement for seabass (Valente et al., 2006), snakehead (Hashim and Mat-Saat, 1992) and shrimp (Cruz-Suarez et al., 2000). Seaweeds grow in the intertidal as well as in the sub tidal area up to a certain depth where very little photosynthetic light is available. They flourish wherever rocky, coral or suitable substrates are available for their attachment. They are found growing in large quantities along the coasts of India. The major seaweed growing areas include Gulf of Mannar, Gulf of Kutch, Palk Bay, Lakshadweep and Andaman and Nicobar islands.

Lobophora variegata is a species of small thalloid brown alga which grows intertidally or in shallow water in tropical and warm temperate seas. There is interest in the use of seaweeds in the development of low-cost, highly nutritive diets for human and animal nutrition, especially animal nutrition since sea vegetables are able to accelerate the growth of oysters, tilapia, salmon, trout, etc., all of great commercial interest (Fleming et al., 1996). At present seaweeds with elevated protein content and production rates are receiving increasing attention as novel feeds with potential nutritional benefits (Buschmann et al., 2001) and as possible ingredient in fish diets (Wahbeh, 1997).

Lates calcarifer (Bloch), commonly known as Giant Seaperch or Asian seabass is an economically important food fish in the tropical and subtropical regions in the Asia–Pacific. It is a euryhaline, carnivorous and originating in seawater (Harpaz et al., 2005). Because of its relatively high market value it has become an attractive commodity of both large and small-scale aquaculture enterprises. Fish meals which are extensively used in feed for fish and other animals may lead to the continuous exploitation of these natural resources which in turn will become environmentally and economically unsustainable. To date, very little attention has been paid to the nutritional value of algae as a potential substitute of protein and other ingredients in fish feed (Sorensen and Denstadli, 2008). This experiment was undertaken with an aim to evaluate the brown seaweed Lobophora variegata as dietary ingredient in partial replacement of fish protein on growth performance, body composition and survival of Asian seabass Lates calcarifer juveniles.

2 Materials and Methods

2.1 Fish and experimental conditions

A total of 200 seabass Lates calcarifer juveniles were procured from Rajiv Gandhi Centre for Aquaculture (RGCA), Sirkazhi, Nagapattinam district, Tamil Nadu, with proper aeration and then transferred to the laboratory for further study. The juveniles were stocked in ground water and the water samples were collected from culture tanks prior to the feeding experiment and analyzed for different parameters (pH, 7.5; temperature, 25°C, dissolved oxygen, 3.5 mg/L) according to APHA (2005).

2.2 Experimental diets

The dried seaweed (Lobophora variegata) powder was procured from Centre for Advanced Study in Botany, University of Madras, Chennai, India. The feed ingredients such as soya bean, coconut oil cake, ground nut oil cake, tapioca flour, dry fish meal, green gram and egg were purchased from merchants; vitamin mix and cod liver oil were obtained from medical shops at Trichy. Along with these, the dried seaweed Lobophora variegata powder was added in feed mix in known ratio and diets were formulated as shown in Table 1. Feed ingredients were mixed well and brought into colloidal form. These feed mix paste were made into a pellet using a manual pelletizer. Finally these pellets were dried in hot air oven at 27^°C for 48 hrs.

2.3 Water stability test

Feed pellets (5 gm) were placed in fibre-reinforced plastic (FRP) tank filled with 30L filtered freshwater and aerated for 1, 2 and 4 hrs. After each respective hour, pellets were taken out from tanks and dried. The dried feed pellets were weighed and water stability of the feed was estimated using the following formula.

% water stability =100× (Final dry weight)/ Initial dry weight

2.4 Maintenance of fishes

During acclimatization, fishes were fed with boiled egg albumin and control feed without seaweed. Water was routinely changed every-day in order to maintain a healthy environment for the fish apart from providing artificial aeration. This ensured sufficient oxygen supply for the fish and an environment devoid of accumulated metabolic wastes.

2.5 Experimental fish, rearing condition and feeding regime

The fish fingerlings were fed twice a day for about 30 days. The feed was given at 10% of fish body weight. The unconsumed feed, if any, was siphoned out 6 hrs after feeding. Likewise, faecal matter was also siphoned out prior to the next feeding.

2.6 Growth and feed efficiency parameters

The growth parameters of the experimental fish fingerlings were assessed by measuring their body weight at 10 days interval. The following response variables were determined from the experimental tank:

Weight gain (%) =100× (Final weight - Initial weight) / Initial weight

Specific growth rate (SGR) (% /day) = 100× (Final weight - Initial weight) / Days of experiment

Feed Conversion Ratio (FCR) (%) =100× [Feed Intake (FI)] / Weight Gain (WG)  

Survival Rate (%) =100× (Number of surviving fish) / Number of stocking fish 

2.7 Biochemical analyses

The biochemical composition in terms of total proteins (Lowry et al., 1951), total carbohydrates (Dubois et al., 1956) and total lipids (Folch et al., 1957) was estimated for both fishes and the formulated feeds.

2.8 Statistical analyses

The given data were expressed in terms of the mean of three replicates ± SD (standard deviation). Data concerning the morphometric and biochemical analysis such as protein, lipid, carbohydrate for seabass fingerlings were analyzed by one-way ANOVA followed by Duncan multiple range test and paired sample t-test between control and experimental groups at p<0.05 by using SPSS Inc. program version 14.

3 Results and Discussion

Growth, health and reproduction of fish and other aquatic animals are primarily dependent upon an adequate supply of nutrients through feed both in terms of quality and quantity, irrespective of the culture system in which they are grown (Kader et al., 2005). Using balanced formulations based on alternative protein sources, primarily of plant origin, has resulted in an improvement in the overall nutritional quality of practical diet formulations (Samocha et al., 2004) as well as considerable reduction in formulation costs. Agricultural by products are one of the cheapest source of ingredients and they are nutritionally rich as well. One fundamental consideration is that algae are the base of the aquatic food chain and are a food resource that fish are adapted to consume.

The chemical composition of macro algae varies with species, physiological status and environmental conditions; however in general, the macro algae are rich in non-starch polysaccharides, vitamins and minerals (Wong and Cheung, 2000). Hamauzu and Yamanaka (1997) reported that early feeding trials with macro algae meal resulted in improvement of vitality, disease resistance and carcass quality whereas Yildirim et al. (2009) reported poor growth and feed utilization for rainbow trout fed with 10% inclusion level of Ulva lactuca. This may be due to the regional and species level differences in the nutritional quality. Moreover marine algae contain essential amino acids and they are reported to have the capacity of texturising well and can be used as a binder for different ingredients in formulated diets (Penaflorida and Golez, 1996).

The growth of fish depends upon the ingredients and their percentages in the formulated feed (Glencross et al., 2007) (Table 1). The present study shows that the juveniles responded well to the formulated diets of seaweed Lobophora variegata and the results are in accordance with Shapawi and Zamry (2016). The ingredients present in the formulated diets significantly influenced the performance of the juveniles which showed final body length and weight increases (Table 2).

The digestibility of a particular feed ingredient is reflected by fish growth. Improvement in growth due to seaweed inclusion was previously noted in fishes by Nakagawa et al., (1984, 1987) and Hashim and Mat Saat (1992). Even at low inclusion levels seaweed meal has resulted as an excellent feed binder and additive (Shapawi et al., 2015). Survival rates obtained in this study with the formulated diets seem to indicate that there were no overwhelming negative effects in utilization of nutrients by the seabass Lates calcarifer juveniles. Higher survival rate was reported in experimental fishes which could be due to the growth promoting substances present in the seaweed. Studies of Chitra (1996) also showed that fish meal mixed with the powder of the marine alga Sargassum wightii gave better growth and weight increment in Oreochromis mossambicus (Table 3). This increase in specific growth rate (SGR) may be due to the enzymatic break down of food, availability of nutrients for absorption (Das et al., 1987).

Seaweed supplemented diets resulted in higher growth in fishes than the control diet, indicated that the addition of seaweed along with the plant by products enhanced the performance of feed utilization. Binders play an important role in pellet preparation. In the present study, egg albumin and tapioca flour were used as binder for pellet formulation. Experimental feeds showed better water stability than the control feeds, due to their high lipid content. Olin et al., (1995) observed that the incorporation of the seaweed in formulated diets increased the water stability of pellets because of the nature of the phytochemicals and stabilizers present in them.

The advantages of partial inclusion of seaweed supplement can be attributed to the balance of dietary fibers, lipid, carbohydrates, minerals and carotenoid together with basic nutritional requirements in fish diet in comparison to commercial diet (Ergun et al., 2013). Protein is the major growth promoting factor in feed. The protein requirement of fish are influenced by various factors such as fish size, water temperature, feeding rate, availability and quality of feeds and overall digestible energy content of diet (Wilson, 2000). Carbohydrates are very efficient energy sources in the most animals for standard metabolism, muscular energy costs and other energy (ATP) requiring process. Carbohydrates are considered to be the first among the organic nutrients can be utilized to generate the required energy.    

Seaweed may also give an important contribute in fish diets as lipid sources (Nakagawa et al., 1987), and binding (Hashim and MatSaat, 1992) or coloring agents (Gouveia et al., 2003). Lipids are primarily included in formulated diets to maximize their protein sparing effect (Hasan, 2001) by being a source of energy. In this study the experimental fishes showed drastic increase in lipid content after fishes subjected to the feeding experiment. Dietary lipids are known to play an important role in animal nutrition as they provide energy, maintain the structural integrity of biological membranes and function as precursors of important steroids (Corraze, 2011).

4 Conclusion

Protein is the largest and most expensive component of aquaculture diets, and nutritionist therefore aim to formulate diets in which the energy required by the animal is provided by non- protein sources. Often the seaweed chosen for fish feeding studies appear to have been selected largely for convenience because they are low cost and commonly available along the Indian coastal waters. From the feed developer’s perspective these findings are very encouraging as the use of seaweed ingredients will significantly reduce the cost of the formulated diet production. Therefore, reducing fish meal inclusion levels and replacing fish meal with cost-effective, widely available and environmentally benign seaweed Lobophora variegata was considered essential for the future development of the aquaculture industry.

Author’s Contribution

U.D conducted the experiments, S.J did data collection and statistical analyses, V.S and N.T gifted the seaweed samples, P.S designed the work and A.S helped in biochemical analyses.

Acknowledgements

Authors are grateful to the Head, Department of Marine Science and authorities of Bharathidasan University, Tiruchirappalli, India, for facilities provided.

References

APHA., 2005. Standard methods for the examination of water and wastewater. American Public Health Association. Washington, D.C. USA.

Buschmann A.H., Correa J.A., Westermeier  R., Hernandez-Gonzalez  M. and Norambuena R., 2001, Red algal farming in Chile: a review. Aquaculture, 194: 203-220.

http://dx.doi.org/10.1016/S0044-8486(00)00518-4

Caruso G., 2015, Use of plant products as candidate fish meal substitutes: an emerging issue in aquaculture productions, Fisheries and Aquaculture Journal, 6: e123, doi:10.4172/2150-3508.1000e123.

http://dx.doi.org/10.4172/2150-3508.1000e123

Chitra G., 1996, Biochemical studies of algae along the coast of Kerala with special reference to industrial application. Ph.D. Thesis, University of Kerala. Trivandrum, India.

Corraze G., 2001, Lipid nutrition. In: Gillaume J., Kaushik S., Bergot P. and Metailler R., (Eds). Nutrition and Feeding of Fish and Crustaceans, Praxis, Chisester, UK, pp 111-129.

Cruz-Suarez L.E., Ricque-Marie D., Tapia-Salazar M. and Guajardo-Barbosa C., 2000, Uso de harina de kelp (Macrocystis pyrifera) en alimentos para camaron. p. 227-266. Editors. L.E. Cruz-Suarez, Denis Ricque-Marie, Mireya Tapia-Salazar, Miguel A. Olvera-Novoa, y Roberto Cerecedo-Olvera. Advances en nutricion Acuicola V. Memorias del Quinto Simposium Internacional de Nutricion Aucicola. 19-22. Noviembre. Universidad Autonoma de Nuevo Leon. Monterrey, Nuevo Leon,   Mexico. ISBN 970- 694-52-9.

Das  K.M. and Gosh A., 1987, Studies on the comparative activity of some digestive enzymes in fry and adult of Mullet, Lisa parsia (HAM). Journal of Aquaculture in the Tropics, 2(1): 9-15.

Dubois M., Gilles K.A., Hamilton J.K., Rebers P.A. and Smith F., 1956, Colorimetric method for the determination of sugars and related substances. Analytical Chemistry, 18: 350-356.

http://dx.doi.org/10.1021/ac60111a017

Ergun S., Soyuturk M., Guroy B., and  Guroy D., 2013, Effect of Ulva  meal on growth performance of Gilt head Sea bream  (Sparus aurata) at different level of dietary lipids. Turkish Journal of Fisheries and Aquatic Sciences, 13: 841-846.

Fleming A.E., Barneveld R.J. and Hone P.W., 1996, The development of artificial diet for abalone. Aquaculture, 140: 5-53.

http://dx.doi.org/10.1016/0044-8486(95)01184-6

Folch J., Lees M. and Sloane-Stanley G.H., 1957, A simple method for the isolation and purification of total lipids from animal tissues. Journal of Biological Chemistry, 97: 383–394.

Francis G., Makkar H.P.S. and Becker K., 2001, Anti-nutritional factors present in plant derived alternate fish feed ingredients and their effects in fish. Aquaculture, 199: 197-227.

http://dx.doi.org/10.1016/S0044-8486(01)00526-9

Glencross B.D., Booth M. and Allan G.L., 2007, A feed is only as good as its ingredients - a review of ingredient evaluation strategies for aquaculture feeds. Aquaculture Nutrition, 13: 17-34.

http://dx.doi.org/10.1111/j.1365-2095.2007.00450.x

Gouveia L., Rema P., Pereira O. and Empis J., 2003, Colouring ornamental fish (Cyprinus carpio and Carassius auratus) with micro algal biomass. Aquaculture Nutrition, 9: 123-129.

http://dx.doi.org/10.1046/j.1365-2095.2003.00233.x

Hamauzu K.. and Yamanaka H., 1997, Usefulness of meal of a sterile mutant of Ulva pertusa as a feed supplement for cultured yellowtail. Suisanzoshoku, 45: 357-363.

Hardy R.W., 2010, Utilization of plant proteins in fish diets: effects of global demand and supplies of fishmeal. Aquaculture Research, 41: 770-776.

http://dx.doi.org/10.1111/j.1365-2109.2009.02349.x

Harpaz S., Hakim Y., Barki A., Karplus I., Slosman T. and Erodogan O.T., 2005, Effects of different feeding levels during day and night on growth and brush border enzyme activity in juvenile Lates calcarifer reared in fresh water re-circulating tanks. Aquaculture, 248: 325-335.

http://dx.doi.org/10.1016/j.aquaculture.2005.03.007

http://dx.doi.org/10.1016/j.aquaculture.2005.04.033

Hasan M.R., 2001, Nutrition and feeding for sustainable aquaculture development in the third millennium. In: aquaculture in the third millennium. Technical proceedings of the conference on aquaculture in the third millennium, Bangkok, Thailand, 20-25 February 2000, 193-219.NACA. Bangkok and FOA, Rome.

Hashim R. and Mat Saat N.A., 1992, The utilization of seaweed meals as a binding agent in pelleted feeds for Snake head (Channa striatus) fry and their effects on growth. Aquaculture, 108: 299-308.

http://dx.doi.org/10.1016/0044-8486(92)90114-Z

Higgs D.A., Dosanji B.S., Prendergast A.F., Beams R.M., Hardy R.W., Riley W. and Deeacon G. 1995, Nutrition and utilization technology in aquaculture Champaign. Chapman and Hall Company,    New york, USA, pp 130-156.

Kadar M.A., Hossain M.A. and Andhasan M.R., 2005, A survey of the nutrient composition of some commercial fish feeds available in Bangladesh. Asian Fisheries Science, 18: 59-69.

Kaushik S. and Hwmre G., 2008, Plant proteins as alternative sources for fish feed and farmed fish quality. In: (Lie, Ø. ed.) Improving armed fish quality and safety. Wood head Publishing, Cambridge, pp. 300-319.

http://dx.doi.org/10.1533/9781845694920.2.300

Kumar C.S., Ganesan P., Suresh P.V. and Bhaskar N., 2008, Seaweed as a source of nutritionally beneficial compounds - A review. Journal of Food Science and Technology, 45: 1-13.

Lowry O.H., Rosenbrough H.J., Farr A.L. and Randall R.S., 1951, Protein measurement with   the folin phenol reagent. Journal of Biological Chemistry, 193: 265-275.

Nakagawa H., Kasahara S. and Sugiyama T., 1987, Effect of Ulva meal supplementation on lipid metabolism of black sea bream, Acanthopagrus Sclegeli (Bleeker). Aquaculture. 62: 109-121.

http://dx.doi.org/10.1016/0044-8486(87)90315-2

Nakagawa H., Kasahara S., Wada I. and Sugiyama T., 1984, Usefulness of Ulva meal as feed supplementary in cultured black sea bream, Suian Zoshoku, 32: 20-27.

Olin P.G., McBride A. and Hain P., 1995, Preliminary artificial abalone diet trials with red abalone, Haliotis rufescens. Educational workshop on current developments in Abalone Enhancement-Project and Aquaculture Industry. Abstract, 8.

Penaflorida V.D. and Golez N.V., 1996, Use of seaweed meals from Kappaphycus alvarezii and Gracilaria heterocladan as binders in diets for juvenile shrimp Penaeus monodon. Aquaculture, 143: 393-401.

http://dx.doi.org/10.1016/0044-8486(96)01282-3

Samocha T.M., Davis D.A., Saoud I.P. and Debault K., 2004, Substitution of fish meal by co-extruded soybean poultry by-product meal in practical diets for Pacific white shrimp Litopenaeous vannamei. Aquaculture, 231: 197-203.

http://dx.doi.org/10.1016/j.aquaculture.2003.08.023

Shapawi R., Safiin N.S.Z. and Senoo S., 2015, Improving dietary red seaweed Kappaphycus alvarezii (Doty) Doty ex. P. Silva meal utilization in Asian seabass Lates calcarifer. Journal of Applied Phycology, 27: 1681-1688.

http://dx.doi.org/10.1007/s10811-014-0454-8

Shapawi R. and Zamry A.A., 2016, Responses of Asian seabass, Lates calcarifer juvenile fed with different seaweed-based diets. Journal of Applied Animal research, 44(1): 121-125.

http://dx.doi.org/10.1080/09712119.2015.1021805

Sorensen M. and Denstadli V., 2008, Alkaline preserved herring by-products in feed for Atlantic salmon (Salmo salar). Animal Feed Science and Technology, 144(3-4): 327-334.

http://dx.doi.org/10.1016/j.anifeedsci.2007.10.011

Tacon A.G.J., Hasan M.R. and Metian M., 2011, FAO Fisheries and Aquaculture technical Paper. 2070-7010. 564.

Tidwell J.H. and Allan GL., 2001, Fish as food: aquaculture’s contribution. EMBO, 2(11): 958-963.

http://dx.doi.org/10.1093/embo-reports/kve236

Valente L.M.P., Gouveia A., Rema  P., Matso J., Gomes E.F. and Pinto I.S., 2006, Evaluation of three seaweed Gracilaria burspastoris, Ulva  rigida and Gracilaria cornea as dietary ingredients in European sea bass (Dicentrarchus labrax) Juveniles. Aquaculture, 252: 85-91.

http://dx.doi.org/10.1016/j.aquaculture.2005.11.052

Wahbeh  M.I., 1997,  Amino acids and fatty acids profiles of four species of macro algae from  Aqaba and their suitability for use in fish diets. Aquaculture, 159: 101-109.

http://dx.doi.org/10.1016/S0044-8486(97)00183-X

Wilson R., 2000, Channel catfish Ictalurus punctatus. In: handbook of nutrient requirement of finfish (ED: R.P. Wilson), CRC Press. Boca Raton Ann Arbor, Boston, London, 35-53.

Wong K.H. and Cheung P.C., 2000, Nutritional evaluation of some subtropical red and green seaweeds. Proximate composition, amino acid profiles and some physico-chemical properties. Food chemistry, 71: 475-482.

http://dx.doi.org/10.1016/S0308-8146(00)00175-8

Yildirim O., Ergun S., Yaman S. and Turker A., 2009, Effects of two seaweeds (Ulva lactuca and Enteromorpha linza) as a feed additive in diets on growth performance, feed utilization, and body composition of rainbow trout (Oncorhynchus mykiss). Kafkas Universitesi Vet Fak Dergisi, 15(3): 455-460