People have been cultivating Tilapia for years: a bas-relief on a 4000-year-old Egyptian tomb shows tilapia held in ponds. Tilapia are low on the food chain and adaptable.
Welcome to Expert Topic. Each issue will take an in-depth look at a particular species and how its feed is managed.
TILAPIAEXPERT TOPIC
Tilapia a well travelled fish that finds a market everywherePeople have been cultivating Tilapia for years: a bas-relief on a 4000-year-old Egyptian tomb shows tilapia held in ponds. Tilapia are low on the food chain and adaptable.
1USAWhitefish USADespite the overall decline in per capita fish consumption in the US, popularity of tilapia continues to grow.
According to the National Fisheries Institute, consumption of whitefish in the USA (cod, pollock, tilapia and pangasius) surpassed that of shrimp and rose by 6.2 percent in 2012. Together with pangasius, tilapia is the main driving force behind the growth in white-fish consumption in the USA in recent years. According to the USDA, the USA market consumes close to 226,000 tonnes of tilapia a year, more than four times the amount only a decade ago.
Nearly all tilapia farmed in the USA are
raised in recirculating aquaculture systems often employ “bio-filters” — microorganisms that feed on nitrogen — to treat wastewater.
Bacteria break down some fish waste into nitrogen (which the microorganisms absorb for fuel) and other organic compounds that can be used to grow plants and algae, which are fed back to the fish. Sediment is removed from the tanks mechanically, and 99 percent of the water is recycled.
FAO Globefish reports that demand for tilapia, including high value fresh fillets, has grown strongly. Indeed, from January to September 2013, imports of fresh/chilled (air-flown) tilapia fillets into the USA increased sig-nificantly by more than 40 percent in volume and 44 percent in value compared with the same period in 2012.
During the January–September 2013 peri-od, imports from almost all major suppliers were higher except from Ecuador, which dropped its shipments to the USAby 17 per-cent compared with the same time period in 2012. Fresh tilapia fillets from Honduras, now the number one supplier of fresh product, were up by almost 30 percent. Amounts from Costa Rica and Colombia increased by 86 percent and 47 percent respectively.
During the first nine months of 2013, a total of 137,300 tonnes of frozen tilapia were imported, down eight percent from the same period the previous USA year.
However, import values were up 17 percent to US$693 million. The frozen fillet category, which makes up the largest share of frozen tila-pia product, experienced a 12 percent decline in volume due to significant drop in supplies from China, Indonesia and Honduras.
In addition, much of the production in China is being diverted to African markets.
2ChinaChina unassailable In China, the world’s largest producer of Tilapia, had major issues in 2012 with damag-ing weather, disease and low prices which forced many farmers out of business.
However, production remained stable in Fujian, Guangdong, Guangxi and Yunnan, which are the major producing regions. Since the latter part of 2013, demand for tilapia fry from farmers has increased. Production in 2014 is expected to be an improvement over 2013.
According to FAO Globefish, total tilapia exports from China during the first nine months of 2013 were up seven percent in vol-ume compared with the same time period the previous year, reaching 268,000 tonnes. The most popular category, frozen fillet, declined in volume by four percent while significant increases were noted in whole frozen (+19 percent) and breaded (+16 percent) catego-ries. In terms of value, exports experienced a 16 percent growth to US$925 900 million.
According to national sources, during the first three quarters of 2013, exports of fro-zen fillets to the US, China’s largest market, declined by about 18 percent, while Mexico imported 34 percent more.
Exports of frozen fillets to the EU mar-kets increased, including Spain (+32 percent), Poland (+62 percent) and Germany (+19 percent). Exports in this product category to Costa Rica, Peru and Colombia also grew, while exports to Iran and Southeast Asia (Malaysia, Vietnam and Thailand) increased by a total of 138 percent.
For the first three quarters of 2013, the whole frozen category experienced a 39 percent increase in value to US$196 million. This category also took a larger share of the total export volume at 36 percent compared with 32 percent in the same time last year. This growth was largely facilitated by higher exports to African and Middle Eastern mar-kets.
Alternative markets for China, such as in Africa, are being explored due to the stringent quality requirements the processing facilities must meet for export to the USA and EU. Supply constraints have also led processors to either reduce processing or focus on whole products to gain higher margin returns.
3TaiwanTaiwan on filmTaiwan PC produces an average of 70,000 tonnes of tilapia annually, 60 percent of which is exported to the US, Canada, Saudi Arabia and Republic of Korea.
In terms of frozen tilapia, Taiwan PC exported 24,189 tonnes in the January–September 2013 period, a 31 percent increase compared with the first three quarters in 2012. The majority of the frozen category was taken by whole tilapia at a 90 percent share. Exports of whole frozen tilapia increased to almost all markets except for Saudi Arabia, Japan and Qatar.
In recent news, the Fisheries Agency
announced that Taiwan PC will be taking active steps to promote tilapia raised in the country. Marketing plans include producing “films to introduce Taiwan’s high-quality tilapia production industry” to promote Taiwanese tilapia and help improve the image of the industry.
Additionally, several of the Republic of Korea’s importers were invited by the Fisheries Agency and local industry groups to visit tilapia farms in Taiwan and were reported to have approved of the high quality of the fish farms. The Republic of Korea is a major importer of Taiwanese tilapia, mostly as frozen fillets.
4VietnamVietnam’s potentialIn recent years, Vietnam’s tilapia exports have been recorded in small volumes.
During January to September 2013, Vietnam exported about 1000 tonnes of tilapia to the EU and US. The EU absorbed the majority, at 80 percent.
In light of the challenges being faced by the Pangasius industry, Vietnam is now looking to tilapia production as another potential for export. It was reported that the An Giang province will be a hub to develop tilapia farming for export, with the Aquatic Breeding Production Center training farmers to produce fingerlings in the province and ensure sufficient seed supply.
5BrazilAmazed by BrazilAmazingly, Tilapia production in Brazil is grow-ing at an average rate of 17 percent annu-ally. According to The Ministry of Fisheries and Aquaculture (MPA), tilapia production exceeded 253,000 tonnes in 2011, showing strong growth compared with 2010 (+63 percent), when production amounted to 155,000 tonnes.
The Ministry of Fisheries and Aquaculture (MPA) plans to invest BRL 252,000 (US$107 860) in tilapia genetic improvements. The project aims to train researchers and develop new products for the Brazilian tilapia industry.
6TrinidadTrinidad surpriseTrinidad is the surprise packet as there has been a significant increase in demand for farm-raised tilapia. This demand has been
growing since 2013, after the Ministry of Food Production embarked on a promotion campaign and introduced initiatives to open more markets for local farmers.
There are also plans to boost produc-tion from farmers with not enough capac-ity to meet the growing demand. The Sugar Cane Feeds Centre (SFC) in Longdenville has developed an arrangement to purchase tilapia from farmers and process and market the fish themselves. The SFC report that consumers have been buying more farmed-raised fish because of concerns regarding pollutants fol-lowing the oil spills in December 2013.
7AustraliaStrange AustraliaStrangely, in Australia Tilapia is considered a noxious pest!
One of the main species found in Australian waters is Oreochromis mossam-bicus (Mozambique Tilapia) and that is a species that normally lives in brackish water.
In many parts of Australia there are issues in arid land areas with salty water. It makes it very difficult to use the land/water for growing crops and vegetables but is ideal for growing fish and certainly growing tilapia but regretta-bly it is not allowed as Australia would rather invest in ‘silver bullets’.
“Tilapia is a popular food fish in Asia, Africa and the South Pacific.
“However, the use of tilapia for con-sumption in Queensland is illegal,” states
EuropeThe European Union connectionIn the EU they imported 24 percent more frozen tilapia fillets during the first nine months of 2013 compared with the same time period in 2012. This confirms the positive trend from the first quarter of the 2013 with close to 17,000 tonnes, up 28 percent from the same period in 2012.
Supplies from Indonesia, Vietnam and Thailand continue to contribute margin-ally to the EU’s imports while China remains the dominant source, supplying 99 percent of the market. Spain, Poland, Germany, The Netherlands and Belgium are the largest importers of tilapia within the EU.
AsiaAsia’s Lunar New YearAsia has a strong affinity to Tilapia and in response to the Lunar New Year demand, prices of live tilapia have peaked in retail markets as well as in restaurants in Malaysia, Singapore and Taiwan PC. In Malaysia, live tilapia comes almost entirely from local sources, while Singapore gen-erally imports its supplies. In Malaysia, ex-farm prices of live tilapia have risen from US$2.8 per kg in November 2013 to US$3.75 per kg in January 2014.
As part of the Lunar New Year promotion, wholesale live fish retailers in Kuala Lumpur are offering fish bundle deals, which feature tilapia (sold as Red Pearl) and jade perch sold together. Prices for bundles in January 2014 ranged from US$37 per kg to US$105 per kg. Meanwhile, live tilapia are sold at US$5.60 per kg and are expected to be 10–20 percent higher during the Lunar New Year week. In seafood restaurants, live tilapia is priced at US$15–19 per kg.
42 | INTERNATIONAL AQUAFEED | March-April 2014
EXPERT T●PIC
the Queensland Government in FAQ’s on Deciphering Legal Jargon (http://www.daff.qld.gov.au/documents/Fisheries_PestsAndDisease/Stop-the-spread-Module-3.pdf).
However in the very same document the New South Wales Government states “Can people eat tilapia? It is not illegal to consume tilapia in New South Wales, as long as the species isn’t being possessed alive. However, you are strongly advised not to use the spe-cies for consumption, as it is in the best inter-ests of the environment to keep the species out of circulation in Australia.” Confused now?
In another part of CSIRO they have produced a document “Our Future World — Global Megatrends” where they state “whilst the state of biodiversity is in decline and the pressure is rising so too is the human response.”
(Are we to save what we cannot and miss out what we need? Tilapia produces a relatively cheap, white, skinless filleted fish that does not taste like fish and demand for the product worldwide is expanding so Australia has made a strange decision – Publisher).
FAO last wordAccording to FAO Globefish demand for
tilapia, particularly for the live market, has peaked in many Asian markets corresponding to the Lunar New Year’s high consumption period. In China, there is concern over ris-
ing competition from lower value species, namely Pangasius in the frozen fillet segment. In turn, exporters are targeting alternative markets. However, overall tilapia production is expected to increase in 2014.
March-April 2014 | INTERNATIONAL AQUAFEED | 43
EXPERT T●PIC
19.000más de
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CHILE
Participe enVIII VERSIÓN22 al 25 de Octubre de 2014Puerto Montt, Chile.
and virulence variation [9, 29, 20, 45, 46, 37, 16, 38, 1]. This fact turns this disease into a bacteriology minefield.
TreatmentThe main method of treatment is use of
antibiotics. Oxytetracycline has often been used around the world against RTFS [39, 4, 22, 28]. Amoxycillin and oxolinic acid have widely been used In Europe [4, 6]. However the development of antibiotic resistance makes antibiotics an unsustainable method of treatment [15].
A lot of effort has been put into develop-ing a vaccine but little progress has been made so far [15, 1]. Some experiments with injectable vaccines, that have used either formalin-killed or heat-inactivated bacteria, have shown some promise but such vaccines
will be very impractical for farm scale fry inoculations [15, 1]. Until a viable vaccine is produced, the industry will have to rely on the use of antibiotics for treatment, along with good biosecurity and husbandry measures to possibly avoid the outbreaks.
Barnes & Brown (2011) [1] suggested that dietary research is warranted, such as an evaluation of novel dietary ingredients in feeds or improved feed formulations that lead to changes in RTFS susceptibility.
Orego-Stim Aquatract LOrego-Stim® is a natural feed additive
based on oregano, developed by Meriden Animal Health. The oregano essential oil acts as an immunity enhancer and growth promot-er, with further benefits including antibacterial and antimicrobial properties.
This section will be divided into two sub-sections. The first outlines the mode of action of oregano essential oil and the second dem-onstrates its immunity-boosting properties in aquaculture species. All the data in these sections is obtained from studies conducted by Meriden Animal Health.
Note: As the scope of this paper focuses on the antimicrobial and antibacterial effects of Orego-Stim®, growth promoting results are not shown in the main text, however results from commercial trials studying the growth promoting effects of the product on Rainbow trout, are shown in appendix 1 for reference.
Mode of ActionIndirectly, Orego-Stim® acts as a growth
promoter and an appetizer. It improves feed intake and digestion, boosts immunity and has antioxidant and anticoccidial properties. Primarily however, it is an antibacterial.
In general, gram-negative bacteria, in contrast to gram-positive bacteria, have both a cytoplasmic membrane and an outer lipid cell membrane with a much smaller peptidoglycan in between. As the ancestral types of bacteria do not have the outer-layer, it has been suggested that this extra outer-layer in the gram-negative bacteria has evolved as a protection against antibiot-ics. This is a theory that could explain why
Table 2: Phagocytosis Activity of Catfish under normal conditions
The nutritional & immune impact of Azomite in Tilapia and Shrimpby Damon Fodge and Doug Fodge, DF Intl., LLC, Dirk Lorenz-Meyer, Behn Meyer EU, GmbH and William T.H.C. Chang, Lytone Enterprise, Inc.
Azomite® is the trade name for a naturally occurring mineral product that has been used to supplement livestock and aquatic
diets throughout the world for over a decade.
During this time, a significant amount of data has been accumulated from the use of the product in farm trials, university tests and private research organisations. At this point, it is clear that azomite improves the quality of animal feed and this leads to improvements in performance, but a solid understanding of the exact mode of action remains illusive.
The name is an acronym for ‘A to Z of minerals including trace elements’.
It is mined from a deposit rich in trace min-erals in the central part of the state of Utah in the United States. Millions of years ago this region was part of a freshwater lake and the azomite site was formed when a volcano spewed millions of tons of ash into that lake.
Today, the deposit exists as several large hills and the site provides the source of the natural inorganic mineral, which typically con-tains approximately 70 trace elements. The chemical composition reflects both the vol-canic and freshwater sources (www.azomite.com).
The material is listed in the US Code of Federal Regulations (21 CFR 582.2729) as
an anticaking agent for livestock feed and is generally recognised as safe (GRAS) by the US Food and Drug Administration (FDA).
Agriculture and livestock producers have used azomite to improve feed quality and as everyone knows improving feed quality leads to better livestock health and plant nutrition. Azomite falls well within the guidelines for use in animal feed by the Association of American Feed Control Officials (AAFCO).
Hundreds of years ago it was used by the local native people in agriculture. This eventually led European settlers to explore the natives’ use of it for their animals and gardens. In modern times, an entrepreneur named Rollin Anderson mined the product in the 1940s and gave samples to friends, some of whom were skilled at testing agricultural products. Mr Anderson’s activity paved the way for azomite’s use in sizeable international animal and agriculture markets.
Poultry, shrimp and tilapia farmers have used it in their feed in conjunction with their regular trace mineral mix for many years and claim that it boosts the quality of their feed and leads to improvements in weight gain, feed conversion and livability. Examples of the impact that the product has on live performance in tilapia and shrimp (Burapa and Shanghai Ocean Universities, respectively) are shown here. This research has shown improvement in weight gain and feed conver-sion of up to 10 percent in multiple scientific tests.
Improved availabilityTrace minerals are essential in animal
diets because they participate in biochemical processes required for normal growth and development.
However, examination of azomite and its typical amount of 70 elements reveals that
there are not enough of the essential trace and ‘ultra trace’ elements to be the sole min-eral source for the proper nutritional develop-ment of animals and plants (Hooge, 2008).
Moreover, perhaps no more than one percent of this inorganic product is soluble in water (Ba, B, Ce, Co, Cr, Ln, & Zn are sparingly soluble, Larsen 1990s), and X-ray diffraction analysis reveals that the product exhibits <18 percent physical structure (due to a small amount of granite and pseudo granite in the product) and the remainder of the product is amorphous, without discernible physical structure.
Perhaps this lack of physical structure improves the availability, but that has not yet been tested.
Although the product is an HSCAS (Hydrated Sodium Calcium Alumina Silicate) the lack of physical structure makes it an atypical HSCAS.
When the materials was introduced to the meat industry, researchers already knew that natural inorganic minerals in use at that time were poorly absorbed and did not fully satisfy an animal’s nutritional needs.
Efforts to increase the absorption and metabolism of six or seven of the well-known trace minerals are still underway, but efforts have already provided metal chelates that exhibit much improved bioavailability due to unique chemical characteristics (AAFCO, 1997). The use of natural inorganic minerals in animal diets has decreased because they typically provide <25 p[ercent of the minerals needed by animals.
Significant improvementAzomite does not appear to fit the gener-
alisations about inorganic minerals. Two decades of animal scientific testing of
the product for weight gain, feed conversion and livability improvements revealed that >85 percent of the tests yielded significant (p < 0.05) improvements.
In these tests, all feeds contained the regular commercial trace minerals to which azomite was added. These successes raise a question: with a trace mineral content that is low and practically insoluble in water, what
Table 1:
AZOMITE® % 1st Deaths (O2) 50% Death (O2) 100% Death (O2)
could explain these benefits? That question leads to a multitude of hypothetical explana-tions, but we tested two simple hypotheses:
1) that azomite inclusion in feed leads to improvements in animals because digestive enzymes are boosted and;
2) improved livability is due to increases in innate immune enzymes (Liu et al. 2009) and (Fodge et al. 2011).
A few other supportive tests were also conducted.
Studies in feedResearchers added test amount of azomite
to standard tilapia and shrimp rations. An equal amount of flour was replaced in
the experimental diets by the azomite, and the diets were not isocaloric. Three or four replications per test group were used in the tests. Dissolved oxygen, pH, temperature, etc. were maintained as close to normal as pos-sible. Enzyme activities were measured using standard test materials available commercially.
In addition to the measurements of enzyme activities, investigators also measured weight gain, livability and feed conversion (FCR) and although not shown, weight gain boosts were @15%, FCR improvements @10% and livabil-ity was better in the presence of the material.
As is clear from the study on digestive enzymes shown below, 0.2% to 0.5% azomite boosted the activity of 4/5 of the proteo-
lytic enzyme activities that were measured and also increased lipase activity in the shrimp. Some enzyme activities were increased as much as 30-40%, and this result helps explain why one obtains weight and FCR improvements.
Although not shown, dry matter and crude protein digestibility were assayed in the tilapia and both were improved (p <0.05) 9.9% and 1.75%, respectively.
Enzymes of tilapia and shrimp innate immune systems were examined next, and the table below shows the results.
azomite in the feed boosted tissue con-centrations of lysozyme (+ @40%), super-oxide dismutase (+ @15%), phenoloxidase (+ >90%) and alkaline phosphatase (+25%). The increases in both digestive and immune enzymes may be a hint that the explanation for the mechanism is quite complex.
To illustrate the potential complexity, azomite’s contribution of individual trace min-erals to feed would contribute @0.1 to 1.0mg/kg to the feed of aquatic animals that require several trace minerals at the level of many mg/kg of each.
To add to the potential complexity of the mechanism, anecdotal reports indicate that less diseased pepper, tomato and grapes occur in the presence of azomite than in it’s absence. It is known that plants depend on an innate immune system that somewhat resem-bles that of invertebrates (Jones and Dang, 2006). Could it be that something more than simple availability or ratio of trace mineral X to Y would be required to explain azomite’s mechanism?
Although the mechanism for induction of such large amounts of enzymes may elude us at this time, shrimp and fish are subjected to more challenges by pathogens and oppor-tunistic pathogens than other commercial
animals, and it is interesting that feeding animals a small amount of asomite appears to more adequately equip them to meet such challenges.
To establish that an increase in immune enzymes was not an artifact, the researchers challenged shrimp with Vibrio alginolyticus and measured the accumulated mortality four days after infection.
Only 13.5% of the shrimp that did not receive any AZOMITE® in their diets were alive after four days, but @ 43.5% of those with @ 0.4% azomite in their feed were still alive.
The aquaculture research and develop-ment teams did not measure antibody synthe-sis +/- azomite, but poultry researchers have, as the test result below indicates.
There were four test groups with eight baby chicks per test group.
Feed for each group received 0.5% of sand or calcium bentonite or sodium bentonite or azomite, all of which were similar particle size. At 16 days, each chick was injected with sheep red blood cells (SRBC) and six days later blood samples were taken from each bird to measure total antibody and IgG activi-ties/ml specific toward SRBC.
As is clear, the antibody level in blood from the birds eating azomite contained @66% more antibody activity than any of the other groups (p < 0.05).
Next, the aquaculture researchers wanted to determine if azomite-treated feed would help shrimp survive hypoxia. They subjected shrimp that had consumed azomite in the feed to gradual oxygen deprivation (see below).
The group with 0.4% azomite in the feed withstood hypoxia the best, but in our opinion more rigorous testing is needed to confirm this result.
Nonetheless, lack of dissolved oxygen for shrimp and fish has a profound impact due to the extreme growth densities of commercial animals. Invertebrates depend on hemocytes to phagocytize pathogens identified by innate immune receptors. Movement of hemocytes to sites of inva-sion and the total number of hemocytes produced under low oxygen tensions would be stressed if animals depend on anaerobic energy metabolism (Direkbusarakom and Danayadol, 1998 and Le Moullac et al., 1998).
Studies when added to shrimp pond soilsShrimp farms have tested azomite by
fertilizing the soil of the ponds between grow-out periods. Pond soils are treated with @200kg/ha. Live performance, mortality, pH, phytoplankton and zooplankton and dissolved oxygen levels are measured.
In one thorough field study (six matched ponds – three were control and three were test ponds), an average of 17% increased
weight and 30% less mortality were observed in the azomite ponds.
Moreover, both zooplankton and phy-toplankton levels were boosted 800-900%. pH values taken in the morning and at noon were numerically slightly higher in the test group than the control, but dissolved oxygen in the test group was increased @30% in the morning and was still 8% better at noon than the control values.
Currently, asomite is added to the pond soil between grow-outs at shrimp farms, especially extensive farms, in several countries.
For years it has been known that it is necessary to have the correct forms of trace minerals available for animals and to provide those trace minerals in the correct propor-tions - an observation that is perhaps as important as the presence of a 100% available metal-chelated mineral.
Little research is underway that explores the ratios of ultra trace minerals to each other as ‘university personnel’ who might be able to provide answers are faced with limited avail-able funding for such exploratory research.
Our conclusion is that the proportions of trace minerals should receive higher priority in future research.
ConclusionAzomite appears to enhance tissue protein
synthesis (perhaps even beyond simply diges-tive and innate immune enzymes) leading to improvements in weight gain, feed conversion ratio and lean yield in aquatic species.
Moreover, the product improves the sur-vival rate, apparently due to its ability to boost the immune enzyme response and perhaps also increase mucosal and shell strength.
It is clear to us that azomite provides some trace minerals that are important in animal nutrition. It will be satisfying to determine the exact nature of those minerals that are not currently being added in most animal diets.
References
Hooge, D. “Natural Minerals Can Benefit Broiler Diets”, Feedstuffs 80(3): 24-26, 2008.
Boyd, J. N. and L. E. Burnett. “Reactive oxygen intermediate production by oyster hemocytes exposed to hypoxia”. J Exp. Biol. 202, 3135-3143, 1999.
Direkbysarakom, S. and Y. Danayadol. “Effect of oxygen depletion on some parameters of the immune system in black tiger shrimp (P. monodon), Adv in Shrimp Biotech., ed. T. W. Flegel, Natl Ctr for Gen. Eng. and Biotech, Bangkok, 147-149.1998.
Le Moullac, G., C. Soyez, D. Saulnier, D. Ansquer, J.C . Avbarre, and P. Levy, “Effect of hypoxic stress on the immune response and the resistance to vibriosis of the shrimp Penaeus stylirostris”, Fish and Shellfish Immunol. 8, 621-629, 1998.
Liu, A., X. Leng, X. Li, L. Wang, Y. Luo, and R. Zhu. “Effects of AZOMITE® on Growth, Intestinal Structure and Non-Specific Immunity of Tilapia (Oreochromis niloticus x O. aureus)”, Chinese Journal Animal Nutrition 21(6): 1006-1011. 2009.
Fodge, D., S. Rattanagulvaron, N.T.M. Huong. “Making strides in aquaculture with natural trace minerals“ AQUA CULTURE Asia Pacific ,Vol. 7(3): 24-25. May/June. 2011.
Rodriguez, A., I. Lopez, E. Sujka, S. De la Cuesta, C. Lopez, and R. Nieto. “Chelated minerals in aquaculture” INTERNATIONAL AQUAFEED, July/August: 22-24. 2013.
Cook, M., N. DiNicola, W. Wu, E. Smalley, “Effects of clay products on Fusarium mycotoxins in broiler chicks”. Report from University of Wisconsin, Dept. of Poultry Science and Immunology, 13 pages, May 26, 1992.
Larsen, C. “Trace elements in AZOMITE® that was dissolved in water”. Western Analysis, Inc., 1 page, @ 1992.
Jones, J.D.G. and J. L. Dang. “The plant immune system”. Nature, 444(16): 323-329, 2006.
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Assessing the potential of polychaete meal in
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