ALGAE AS FISH FEED

ALGAE AS FISH FEED

Posted by Unknown

Fish feed is plant or animal material intended for consumption by fish kept in aquariums or ponds. Algae have been used in animal and human diets since very early times. Filamentous algae are usually considered as ‘macrophytes’ since they often form floating masses that can be easily harvested, although many consist of microscopic, individual filaments of algal cells. Algae also form a component of periphyton, which not only provides natural food for fish and other aquatic animals but is actively promoted by fishers and aquaculturists as a means of increasing productivity. Marine ‘seaweeds’ are macro-algae that have defined and characteristic
structures. Microalgal biotechnology only recently began to develop in the middle of the last century but it has numerous commercial applications. Algal products can be used to enhance the nutritional value of food and animal feed owing to their chemical composition; they play a crucial role in aquaculture. Macroscopic marine algae (seaweeds) for human consumption, especially nori (Porphyra spp.), wakame (Undaria pinnatifida), and kombu (Laminaria japonica), are widely cultivated algal crops. The most widespread application of microalgal culture has been in artificial food chains supporting the husbandry of marine animals, including finfish, crustaceans, and molluscs
.
NECESSITY OF PRODUCING FISH FEED
 The essential nutrients present in the aquatic bodies are not sufficient for the fishes for pisciculture for the better growth and development as fishes are cultured in regularly year after year. Thus it causes the depletion of nutrition in the ponds or other aquatic bodies. As a result of increasing water pollution, the production of different zooplanktons and phytoplanktons are also reduced so nutrient deficiency may also occur on that aquatic bodies. For scientific composite and mixed culture of fishes it is necessary to supply the sufficient amount of foods for fishes of different feeder level.   
Fish foods normally contain macro nutrients, trace elements and vitamins necessary to keep captive fish in good health. Approximately 80% of fish keeping hobbyists feed their fish exclusively prepared foods that most commonly are produced in flake, pellet or tablet form. Pelleted forms, some of which sink rapidly, are often used for larger fish or bottom feeding species such as loaches or catfish. Some fish foods also contain additives such as sex hormones or beta carotene to artificially enhance the color of ornamental fish.
Using feeds in aquaculture (sometimes referred to as aquafeeds) generally increases productivity. However, to maximize cost-effectiveness, it is particularly useful in small-scale aquaculture to utilize locally available materials, either as ingredients (raw materials) in compound aquafeeds or as sole feedstuffs.
SOURCES OF FISH FEED
i) Microalgae as fish feed  :-The largest current application of microalgae feeds is in aquaculture. Microalgae are used fresh (e.g. live, or at least not dried) in bivalve, shrimp and fish fry and fingerling production (in the latter case via an intermediate food source, such as zooplankton or brineshrimp) (Benemann, 1992, Spolaore et al, 2006). Several companies produce aquaculture feeds using Chlorella and Spirulina, or a mixture there of. Some examples of the use of microalgae for aquaculture:- Microalgae species Hypneacervicornis and Cryptonemia crenulata particularly rich in protein were tested in shrimp diets (da Silva et al, 2008). Algae were collected, rinsed, dried and ground up for the feed formulations. Larvae shrimps were fed daily with one of four diets prepared
with different percentages of seaweed powder: 39%, 26%, 13%, 0%. The results suggest that there is an increase in feed conversion when the levels of algae are increased. Amount of algae in fish feed resulted in significant increase in shrimp growth rates.
- A large number of marine nitrogen-fixing cyanobacteria have been tested for their nutritional value with the hybrid Tilapia fish fry; a majority were acceptable as single ingredient feeds. Very high growth rates of Tilapia fish using marine cyanobacteria with in-door and out-door cultures have been reported. The marine cyanobacterium Phormidium valderianum was shown to serve as a complete aquaculture feed source, based on the nutritional qualities and non-toxic nature with animal model experiments (Thajuddin et al., 2005).
            Initially, the colour-enhancing effects of phycocyanin-containing Spirulina biomass or carotenoides from Dunaliella were exploited in ornamental fish. In recent years, questions of feed utilization and health status in the dense aquacultural fish populations became more important. Here, the addition of microalgae can, depending on concentration, directly enhance the immune system of fish, as investigations on carp have shown (Schreckenbach et al. 2001).
The addition of microalga-derived astaxanthin to feed formulations enhances the colour of the muscles of salmonids. This has a high biotechnological potential and culture techniques for Haematococcus pluvialis are well developed for this purpose (Piccardi et al. 1999). On the Hawaiian Islands and in China, Haematococcus is cultivated in open ponds (Pulz and Gross, 2004).
More than 40 species of microalgae are used in aquaculture worldwide, depending on the special requirements of local seafood production. In 1999, the production of microalgae for aquaculture reached 1000 ton (62% for molluscs, 21% for shrimps and 16% for fish) for a global world aquaculture production of 43 x 106 ton of plants and animals (Muller-Feuga, 2004). 

ii) Macroalgae as fish feed  : Spirulina is a blue-green plant plankton rich in raw protein, vitamins A, B1, B2, B6, B12, C and E, beta-carotene, color enhancing pigments, a whole range of minerals, essential fatty acids and eight amino acids required for complete nutrition.
The filamentous green alga (Cladophora glomerata) meal was used as the sole source of protein for Nile tilapia. Similarly, Appler (1985) recorded Specific growth rates of 44 % and 56 % of control diets when the filamentous green alga (Hydrodictyon reticulatum) meal was used as the sole source of protein for O. niloticus and T. zillii.
Tacon et al. (1990) used fresh live seaweeds (Gracilaria lichenoides and Eucheuma cottonii) as the total diet for rabbitfish in net cages. The brown algae Ascophyllum, Laminaria and Undaria; the red alga Porphyra; and the green alga Ulva are also used as fish feed for different types of fishes.

Species
Common or commercial name
Porphyra sp.
Nori - laver
Undaria pinnatifida
Wakame
Himanthalia elongata
Sea bean
Ulva sp.
Sea salad
Palmaria palmata
Dulse
Chondrus crispus
Irish moos or Pioca or lichen carragheen
Gracilaria verrucosa
Ogonori
Enteromorpha sp.
Aonori
Ascophylum nodosum
Black Goëmon
Fucus vesiculosus et spiralis
Black Goëmon

ALGAL SPECIES FOR COMMON FISH FEED

FISH                                                                    ALGAE
  Catla catla
Fingerlings:      Anabanea sp.; Microcystis sp.; Oscillatoria sp.; spirulina sp. Botryococcus braunii; chlamydomonas sp.; Closterium sp.; Coelastrum microporum; Eudorina elegan; Pandorina morum; Pediastrum simplex; Tetrahedron minimum;

Adult:                        Anabaena sp.; Microcystis sp; Oscillatoria sp.; Spirulina sp.;
                                 
                                  Chlamydomonus.; Closterium sp.; Coelastrum sp.; Eudorina sp.; Pandorina.; Pediastrum.; Volvox sp.;
                                 
                                  Cyclotella sp.; Navicula sp.; Pinnularia sp.;
                                 
                                  Ceratium.; Peridinum sp.;
                                 

Labeo rohita
  Fingerlings:        Carteria sp.; Chlamydomonas sp.; Chlorogonium sp.; Eudorina sp.; Pandorina sp.; Pleodorina sp.; Volvox sp.;

                                  Closterium sp.; Staurastrum sp.; Xanthidium sp.;

Adult:                        Chlorogonium sp.; Closterium sp.; Eudorina sp.; Gonium sp.; Pandorina sp.; Volvox sp.; Xanthidium sp.;

                                  Botryococcus sp.;

                                  Mallomonus sp.; Synura sp.;

                                  Ceratium sp.; Peridinium sp.;

                                  Anabaena sp.; Microcystis sp.; Oscillatoria sp.; Spirulina sp.;

CHEMICAL COMPOSITION OF ALGAE

A summary of the chemical composition of various filamentous algae and seaweeds is presented in Table 2. Algae are receiving increasing attention as possible alternative protein sources for farmed fish, particularly in tropical developing countries, because of their high protein content (especially the filamentous blue-green algae). The dry matter basis (DM) analyses reviewed in Table 2 show that the protein levels of filamentous blue green algae ranged from 60–74 %. Those for filamentous green algae were much lower (16–32 %). The protein contents of green and red seaweeds were quite variable, ranging from 6–26 percent and 3–29 % respectively. The levels reported for Eucheuma/ Kappaphycus were very low, ranging from 3–10 %, but the results for Gracilaria, with one exception, were much higher (16–20 %). The one analysis for Porphyra indicated that it had a protein level (29 %) comparable to filamentous green algae. Some essential amino acids is also contained in various aquatic macrophytes.
The lipid levels reported for Spirulina (Table 2),with one exception (Olvera- Novoa et al. (1998), were between and 4 and 7 %. Those for filamentous green algae varied more widely (2–7 %). The lipid contents of both green (0.3–3.2 percent) and red seaweeds (0.1–1.8 %) were generally much lower than those of filamentous algae. The ash content of filamentous blue-green algae ranged from 3–11 % but those of filamentous green algae were generally much higher, ranging from just under 12 %t to one sample of Cladophora that had over 44 %. The ash contents of green seaweeds ranged from 12–31%. Red seaweeds had an extremely wide range of ash contents (4 to nearly 47 %) and generally had higher levels than the other algae.
Nutritional Quality of Algae : Of the unorthodox feed sources, algae appear to have most potential for development as an alternative to fish-meal and soybean meal. Table 2 gives the gross chemical composition of some algal species.
Algae is a nutritionally-good fish food. Besides the high levels of protein, lipids and carbohydrates, it contains appreciable amounts of valuable vitamins.

Table 2. Chemical composition (% of dry matter) of selected algae.
Algae
Protein
Lipids
Carbohydrates
Spirulina platensis
46 – 50
4 – 9
8 – 14
Spirulina maxima
60 – 71
6 – 7
13 – 16
Chlorella vulgaris
51 – 58
14 – 22
12 – 17
Chlorella pyrenoidosa
57
2
26
Scenedesmus obliquus
50 – 56
12 – 14
10 – 17
Scenedesmus quadricauda
47
2

Dunaliella salina
57
6
32
Synechococcus
63
11
15
Euglena gracilis
39 – 61
14 – 20
14 – 18
Hormidium
41
38

Ulothrix
45
1


Algal lipids are usually esters of glycerol and fatty acids having C12 to C20. While different algal groups contain different lipids, the major components include triglycerides, sulphoquinovosyl diglyceride, monogalactosyl diglyceride, digalactosyl diglyceride, lecithin, phosphatidyl glycerol, and phosphatidyl inositol. The total lipid content in algae range from 1 to 40% of dry weight. Cyanophyta contains large amounts of polyunsaturated lipids, while other groups of algae contain saturated and monounsaturated fatty acids abundantly.
Besides these, algae contain pigments like chlorophylls and carotenoids, which make up to 5 % dry weight. B-carotene is a precursor of vitamin A and is commercially valuable as a colour enhancer for many species of fish.
The limitation to the use of algae as feed is the digestibility of the cell wall. For incorporation into artificial diet, processing of the algal biomass by drum-drying or freeze-drying can achieve digestibilities up to 90 % (Jauncey, 1982). Studies on the use of algal meals in artificial diets show that algae is the only vegetable protein source that can replace fish meal (Becker 1986).
The rate of photosynthesis in tropical fishponds is about 4gC/m2/day or 30t dry weight algae/ha/yr (Colman & Edwards, 1987). Assuming a feed conversion ration of 2:1 (dry algae to wet fish), the maximum fish yield is about 15t/ha/yr (Pullin, 1988). If the C:N:P ratio of algal cells is 50:10:1 by weight (Goldman, 1979), then to maintain the photosynthetic rate of 4 g C/m2/day in a 1 m deep pond would require daily inputs of 4 g C, 0.8 g N and 0.08 g P per m2 pond area/day.

PRODUCTION OF ALGAE
As in the case of their environmental conditions, the methods for culturing filamentous algae and seaweeds vary widely, according to species and location. This topic is not covered in this review but there are many publications available on algal culture generally, such as the FAO manual on the production of live food for aquaculture. Concerning seaweed culture, the following summary of the techniques used has been has been extracted from another FAO publication (McHugh, 2003) and further reading on seaweed culture can also be found in McHugh (2002). Some seaweeds can be cultivated vegetatively, others only by going through a separate reproductive cycle, involving alternation of generations.
In vegetative cultivation, small pieces of seaweed are taken and placed in an environment that will sustain their growth. When they have grown to a suitable size they are harvested, either by removing the entire plant or by removing most of it but leaving a small piece that will grow again. When the whole plant is removed, small pieces are cut from it and used as seedstock for further cultivation. The suitable environment varies among species, but must meet requirements for salinity of the water, nutrients, water movement, water temperature and light. The seaweed can be held in this environment in several ways: pieces of seaweed may be tied to long ropes suspended in the water between wooden stakes, or tied to ropes on a floating wooden framework (a raft); sometimes netting is used instead of ropes.In some cases the seaweed is simply placed on the bottom of a pond and not fixed in any way;
in more open waters, one kind of seaweed is either forced into the soft sediment on the sea bottom with a fork-like tool, or held in place on a sandy bottom by attaching it to sand-filled plastic tubes. This is typical for many of the brown seaweeds, and Laminaria species are good examples; their life cycle involves alternation between a large sporophyte and a microscopic gametophyte. The sporophyte is harvested as seaweed.
Where cultivation is used to produce seaweeds for the hydrocolloid industry (agar and carrageenan), the vegetative method is mostly used, while the principal
 seaweeds used as food must be taken through the alternation of generations for their cultivation.
WAY OF USING ALGAE
Several feeding trials have been carried out to evaluate algae as fish feed. Algae have been used fresh as a whole diet and dried algal meal has been used as a partial or complete replacement of fishmeal protein in pelleted diets.
1. Algae as major dietary ingredients
The results of the earlier growth studies showed that the performances of fish fed diets containing 10–20 percent algae or seaweed meal were similar to those fed fishmeal based standard control diet. Only about 10–15% of dietary protein requirement can be met by algae without compromising growth and food utilization. There was a progressive decrease in fish performance when dietary incorporation  of algal meal rose above 15–20 %. However, although reduced growth responses were recorded with increasing inclusion of algae in the diet, the results of feeding trials with filamentous green algae for O. niloticus and T. zillii indicated that SGR of 60–80 percent of the control diet could be achieved with dietary inclusion levels as high as 50–70 percent.

Algae
Inclusion
level (%t)
Fish species
Effect
Red algae
Porphyra yezoensis


Porphyra spheroplasts



      5




Red sea bream

Increased growth, feed efficiency and protein deposition. Elevated liver glycogen and triglyceride accumulation in muscle Mustafa et al. (1995)
urvival, growth and nutrient retention significantly higher than control Kalla et al. (2008)
Green algae
 Ulva conglobata

Ulva pertusa




Ulva pertusa

      5

      5




      5

Nibbler

Black sea bream




Red sea bream

Improved growth Nakazoe et al. (1986)

Ulva meal diets repressed lipid accumulation in intraperitoneal body fat without loss of growth and feed efficiency. Fish fed 2.5, 5 and 10 % Ulva meal did not show significant body weight loss during wintering. During starvation, lipid reserves were preferentially mobilized for energy Nakagawa et al. (1993)
Demonstrated a decrease in susceptibility to Pasteurella piscicida, an elevation of phagocytosis and spontaneous haemolytic and bactericidal activity. Satoh, Nakagawa and Kasahara (1987)
Increased growth, feed efficiency and protein deposition. Elevated liver glycogen and triglyceride accumulation in muscle Mustafa et al. (1995)


Recent work by Kalla et al. (2008) appears to indicate that the addition of Porphyra spheroplasts to a semi-purified red seabream diet improved SGR. In addition, Valente et al. (2006) recorded improvements in SGR when dried Gracilaria busra-pastonis replaced 5 or 10 % of a fish protein hydrolysate diet for European seabass.
Total replacement of fishmeal by algal meal showed very poor growth responses for O. niloticus (Appler and Jauncey, 1983; Appler, 1985) and T. zillii (Appler, 1985). Appler and Jauncey (1983) recorded a SGR of 58 % of control diet when the filamentous green alga (Cladophora glomerata) meal was used as the sole source of protein for Nile tilapia. Similarly, Appler (1985) recorded SGRs of 44 % and 56 % of control diets when the filamentous green alga (Hydrodictyon reticulatum) meal was used as the sole source of protein for O. niloticus and T. zillii. Tacon et al. (1990) used fresh live seaweeds (Gracilaria lichenoides and Eucheuma cottonii) as the total diet for rabbitfish in net cages. Pantastico, Baldia and Reyes (1985) reported that newly hatched Nile tilapia fry (mean weight 0.7 mg) did not survive at all when unialgal cultures of Euglena elongata and Chlorella ellipsoidea were fed to them.
2.  Algae as feed additives
The main applications of microalgae for aquaculture are associated with nutrition, being used fresh (as sole component or as food additive to basic nutrients) for colouring the flesh of salmonids and for inducing other biological activities (Muller- Feuga, 2004). Several investigations have been carried out on the use of algae as additives in fish feed. Feeding trials were carried out with many fish species, most commonly red sea bream (Pagrus major), ayu (Plecoglossus altivelis), nibbler (Girella punctata), striped jack (Pseudoceranx dentex), cherry salmon (Oncorhynchus masou), yellowtail (Seriola quinqueradiata), black sea bream (Acanthopagrus schlegeli), rainbow trout (Oncorhynchus mykiss), rockfish (Sebastes schlegeli) and Japanese flounder (Paralichthys olivaceus). Various types of algae were used; the most extensively studied ones have been the blue-green algae Spirulina and Chlorella; the brown algae Ascophyllum, Laminaria and Undaria; the red alga Porphyra; and the green alga Ulva. Fagbenro (1990) predicted that the incidence of cellulase activity could be responsible for the capacity of the catfish Clarias isherencies to digest large quantities of Cyanophyceae.
3. Green water technology :  Green water is a technique of adding microalgae to the
aquaculture / medium where fishes grown as an enhancement, not as a direct food source.The most commonly used microalgae for creating green water id Nannochloropsis, Pavlova and Isochrysis can also be used if there is adequate circulation.These algae reduce the pollutants of water and also added high amount of O2 during their photosynthesis. The use of green water reduces mortality of fish and excels fish health.

PROBLEMS IN USING MICRO ALGAE AS AN FISH FEED
The algae which are used as fish feed sometimes may create a problem due to their low digestibility.Only about 10-15 % of dietary protein requirement can be met by algae in test diets without compromising growth and food utilization. There is a progressive decrease in fish performance when dietary incorporation of algal meal rises above 15-20 %. Total replacement of fishmeal by algal meal generally shows very poor growth responses. Apart from commonly observed impaired growth, the use of algae as the sole source of protein in fish feed can also result in malformation.
The poor performance of fish fed diets containing higher inclusion levels of algae may be attributable to high levels of carbohydrate, of which only a small fraction consists of mono- and di-saccharides. A preponderance of complex and structural carbohydrates may cause low digestibility.
The collection, drying and pelletization of algae require considerable time and effort and algal cultivation is costly. Cost-benefit analysis is needed before any definite conclusions on the future application of algae as fish feed can be drawn. The use of algae as fish feed additives may be limited to the commercial production of high value fish.
In order to overcome or reduce the problems and limitations associated with algal cultures, various investigators have attempted to replace algae by using artificial diets either as a supplement or as the main food source. Different approaches are being applied to reduce the need for on-site algal production, including the use of preserved algae, micro-encapsulated diets, and yeast-based feeds. There is further scope to develop the sector by introducing better quality products, since it is widely acknowledged that existing concentrated microalgae products still do not match live microalgae for hatchery applications.
CONCLUSION
Micro algal biotechnology only really began to develop in the middle of the last century but it has numerous commercial applications. Algal products can be used to enhance the nutritional value of food and fish feed owing to their chemical composition; they play a crucial role in aquaculture. Moderate growth responses and good food utilization were generally recorded when dried algal meal were used as a partial replacement of fishmeal protein. However, the collection, drying and pelletization of algae require considerable time and effort. Furthermore, cultivation costs would have to be taken into consideration. Therefore, further cost-benefit on-farm trials that take these costs into consideration are needed before any definite conclusions on the future application of algae as fish feed can be drawn.
Nevertheless, the results of various research studies show that algae as dietary additives contribute to an increase in growth and feed utilization of cultured fish due to efficacious assimilation of dietary protein, improvement in physiological activity, stress response, starvation tolerance, disease resistance and carcass quality. In fish fed algae-supplemented diets, accumulation of lipid reserves was generally well controlled and the reserved lipids were mobilized to energy prior to muscle protein degradation in response to energy requirements.













0 comments:

Post a Comment