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Yeast in aquaculture


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Yeast products are getting more and more popular in aquaculture. However many products (as a whole or as fractions) are on the aquaculture market at the moment and differentiating between one from another can be difficult. This small article aims at shading some lights on the subject and explains that all yeast products are not equal.

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Yeast in aquaculture

  1. 1. Digital Re-print - January | February 2013 Yeast in aquacultureGrain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies,the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis ofinformation published.©Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any formor by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872
  2. 2. FEATURE Yeast in aquaculture by Philippe Tacon PhD, Lesaffre Feed Additives, FranceY east products are getting more tive price in regards to other protein sources percent dry matter and can contain from and more popular in aquaculture. such as fish or soybean meal. Further appli- 40 to 60 percent crude protein nitrogen, However many products (as a cations are being developed for yeast as 35-45 percent carbohydrates, and 5-9 per-whole or as fractions) are on the aquacul- functional feed additives as probiotic live cent lipids. A quite important fraction ofture market at the moment and differen- yeast, yeast fractions (yeast cell walls, yeast the nitrogen is under the form on nucleictiating between one from another can be extracts) or as a source for more purified acids (up to 12%) that can lead to producedifficult. This small article aims at shading products such as beta-glucans and nucle- significant level of uric acid if consumed atsome lights on the subject and explains otides. The production process of yeast can high concentration, like meat. The aminothat all yeast products are not equal. allow the possibility to incorporate trace acid profile of yeast is close to soybean meal minerals and then produce highly bioavail- and therefore well adapted to animal nutri- Yeast is a unicellular organism belong- able organic trace minerals, also known as tion; it is rich in Glutamic acid and Lysine (uping to the kingdom of Fungi. More than a selenium and chromium yeast. to 8%). Yeast is naturally rich in B vitaminsthousand species have been found in two The pink yeast Phaffia rhodozyma, is such as biotin, thiamine and folic acid. It alsomajor phyla: Basidiomycota and Ascomycota naturally rich in astaxanthin and has been produces niacin but contrary to some beliefin which belong species able to duplicate used for some time as natural source of the does not produce B12 Vitamin. Ergosterolby budding such as Saccharomyces cerevisiae. pigment in salmonids. Although now it tends which is a significant fraction of yeast cell Due to their unique properties to grow to be replaced by bacterial products which wall, also is also a precursor of Vitamin D2under aerobic conditions and produce gas have a higher concentration and whose cell by using UV treatments.and ethanol under anaerobic conditions, some wall is more easily degraded. We will onlyyeast (mostly S. cerevisiae) have been used for refer in the following article on products Baker’s yeastthe manufacture of fermented foods such as coming from S. cerevisiae origin. Even if their name remains Saccharomycesbread , beer and wine for a long time. Yeasts cerevisiae (cerevisiae for beer), most of theare also used as single sell protein source in Nutritional properties of yeast strains of Baker’s yeast have been selectedanimal nutrition and in aquaculture under Typical dry yeast composition is 93-97 for their high fermentative power, particu-various forms and larly useful for bakers. Strainsspecies (Torulaspora, are specific to the type ofTorulopsis, bread and the region whereKluyveromyces, it is sold, in order to respondSaccharomyces and to different bread makingcaetera). They can conditions (French bread,be found for example white bread, flat bread,in shrimp and marine croissant, etc.) and resist tofish larval feeds or different process conditionsincluded as a protein (osmotic pressure from highsource in aquafeeds. sugared bread, freezing, acid- The reasons for ity of sour dough,…).this extensive use is Baker’s yeast comes asits excellent nutri- a pure and primary culturetional contents, its grown on sugar substrateeasy supply in dried such as molasses. The pro-form or under liq- duction is performed underuid form when bak- very strict conditions in orderery yeast plants or to maintain the genetic puri-breweries are near ty, consistency, specificity andaquafeed plants, and Figure 1: Yeast manufacturing process (primary grown culture) efficacy of the strains. (Figurenowadays a competi- 1). It can be sold under differ-26 | January - february 2013 Grain &feed millinG technoloGy
  3. 3. FEATURE Table 1: Effect of live yeast Actisaf on growth and survival parameters in tilapia under stress conditions. (n=3, P<0.05, measures with different letters are significantly different) Treatment Survival (%) SGR FCR PER summit is another and th best-practice of semina the value VIV eight v CON 40% -10 fry 75.0ab 3.33a 3.11e 0.83ab adds to its events. by sup Developed in oped CON 40% -20 fry 64.8a 3.47a 3.26e 0.78ab close co-operation use d with loyal advisors the fee Act 40% - 10 fry 87.5bc 5.80d 1.43abc 1.89cd to VIV, this is a Yia premium-quality Agent Act 40% - 20 fry 92.6c 5.43c 1.01a 2.64d conference based speakin on my personal explain Act 27% - 10 fry 91.7bc 5.46cd 1.62bc 2.26c initiative,” he says. “the a Figure 2: Schema of a process to produce yeast have Act 27% - 20 fry 96.29c 5.24c 1.17ab 3.17e VIV Asia presents three special extracts and yeast cell walls A very special seminar proces features: CropTech-FeedTech Perendale Publishers will be tak- degree Asia, focusing cost-effective feed ing part in one of the CropTech- controent forms and packaging (instant dried yeast, Brewer’s yeast canproduction, MeatTech, highlighting concern is the sanitary safety March be used to produce Another FeedTech Asia seminars on of tially uactive dry yeast, compressed, cream). yeast fractions, however due totechnologies tothese products. 2013. Called are sometimes the latest the nature produce 13, Antibiotics ‘Digital engineering a mea The primary grown culture controlled of brewer’s yeast and safe products that can be added to the process in order to this unique the specificity of the used eas- in feed manufacturing’, prevent ductioprocess makes also a very consistent base for production processes,ily the the consumers, and the VIV seminar with the yeast for nutri-the by quality is less bacteria competing is for those working in Manythe production of yeast extracts, autolysed consistent than in baker’s yeast. Products Asia. and avoiding of milldecrease. It and aims at Animal Health Summit ents area yield technology is there- the huyeast, yeast cell walls and their derivate: coming from brewery yeast tend to have a first confer- providing background information on The summit is the fore possible that some antibiotic residues tic apnucleotides and beta-glucans. Yeast cell walls distinctive bitter smell and taste andto darker the rapidly intelligent solutions be left in the ence in Asia a address and possibly other toxins might that have been includeproduced from Baker’s yeast usually have a colour than the ones growing concerns about the use of product. coming from baker’s final dried introduced to address processing orderhigh content of mannans. They are recognised yeast. antibiotics in animal protein produc- chain dilemmas. Foas good toxin binders. Fractions coming from tion, both at CEO and Autolysed yeast – Inactive Dried technical “What’s unique for our industry ers wilbaker’s yeast have a light beige colour. Ethanol yeast Yeast level. On a personal note, Berculo about this event is its format,” says develo The most popular aquaculture application is particularly excited about the VIV and Autolysed publisher of Grain and Ethanol yeasts are harvested after having Inactive Roger Gilbert, yeast come from will imof Baker’s yeast is in hatcheries where it is performed alcoholic fermentation andSummit Asia. “The Feed Milling or Brewer’s magazine Animal Health distil- primary grown cultures Technology yeast. benefita major feed source for artemia and rotifer lation for the(see for example Couteau et al 1990). conventional productionBrewer’s yeast of Bioethanol Brewer’s yeast can be identified either from sugar-as the ferment used in brewery industries cane, beet(Yeast primary production) or the by-prod- sugar or grainsuct of these industries which is the form syrup. In themainly used in aquaculture. In the latter case, first case, theyeast biomass is harvested from the fermen- yeast biomasstation vats at the end of beer fermentation. is harvestedIt can be sold under liquid form (18-20% and then driedof dry matter) but preferentially as inactive with the recy-yeast spray or drum dried. It can also been cled energygrown as a more controlled product and used to heatspecific strains and find its way to human the vegetalcare as a food supplement and holistic thera- material. Thepeutic, also known as natural brewer’s yeast. majority of Brewer’s yeast for aquafeed applications ethanol yeastis sold by trading companies as a commodity comes frombased on the protein content, or by local Brazil.breweries in need to dispatch their slurry. ProductionThe quality and the supply of these products prices andcan be inconsistent and depends greatly on selling pricesthe source of supply. are very low, The nutritional content is similar as the however theone in baker’s yeast, but contains more trace quality, suchminerals such as selenium and chromium. as the proteinThe protein content of brewer yeast is content is veryrelatively high and and its amino acid content similar to baker’s yeast. Numerous works The supplyhave shown the efficacy of Brewer’s yeast depends onto replace partially or totally the proteins the activity offound in fish and vegetable meal in fish and the bioetha-shrimp. Shrimp feeds formulators typically nol plants andincorporate brewer’s yeast in their formula can also beat the rate of two to four percent. inconsistent.Grain &feed millinG technoloGy Grain &feed millinG technoloGy January - february 2013 | 27
  4. 4. FEATUREThey are major products within the food protein and forms peptides (dipeptides to the gut maturation have been found in seaindustry as flavour enhancers and in pet tetra peptides) and oligonucleic acids which bass with a species extracted from the rain-food as feed attractants. They are used in are readily digestible by the animal. Again bow trout gut Debaryomyces hansenii (seeaquaculture feeds as a source of protein here depending on the original yeast material the works from Tovar-Ramirez and also theand nitrogen. Brewer’s yeast, and its ethanol used, autolysed and inactive yeast quality can reviews by Chi et al 2006 and Gatesoupeequivalent, is mostly favoured as it is cheaper be very different. 2007). Marine yeasts and yeasts isolatedthan baker’s yeast. They are also easier from fish seem a very logical choice to usesupplied as yeast suppliers prefer to sell the Live yeast as probiotics in species of aquaculture interest. However,more controlled and tailored Baker’s yeast Live yeast helps regulate the gut micro- such material is often difficult to grow underon food markets. biota. Its effects have been shown, first in industrial conditions and did not lead to Inactive yeast is a yeast that has been human where it can reduce diarrhoea, espe- the development of an actual product yet.deactivated by high temperature drying cially with children. Specific strains have then The products on the market are therefore(often spray drying). The cells come as a been developed and produced industrially often from S. cerevisiae origin. It has to bewhole and the cell wall is not ruptured mak- such as S. cerevisiae boulardii or S. cerevisiae noted that up to now, no yeast productsing the access to intracellular material (amino Sc 47 (Actisaf) for the animal nutrition have been registered in EU as a probiotic inacids, vitamins…) difficult. A way to access market. It is a common practice now to sup- aquaculture.these materials is to partially hydrolyse the plement feeds to increase milk production in As an example of S. cerevisiae effects,yeast cell wall to let the cellular content be dairy cows or help piglets survival. (Lara Flores et al 2003, 2010) Table 2 showspartially released from the cell. This can be Live yeast are characterized by their living some works done in tilapia fry fed for 3facilitated by activating the internal autolytic cells count, expressed by colony forming unit weeks with feeds supplemented with Actisafenzymes of the live yeast (autolysis), add- (cfu per gram), typically ten billions cfu/g. (also knwn as Biosaf) at 1 kg/T in two dietsing external enzymes (notably proteolysis) Dosages are made in the feeds as dilutions (40% and 27% proteins) and at 2 crowdedor playing on the osmotic pressure to to get an efficient cfu count per g of feed, conditions (1 fry per L or 1 fry per 2L).rupture the cell wall (plasmolysis). Different a 1000 fold dilution giving a 10.107 per g All the yeast treatments also increasedgrades of autolysed yeast can be obtained of feed for example. Viability of the yeast the Alkaline Phosphatase activity, and we candepending on the level of autolysis (from is mandatory for its effect and cfus should see a better improvement of feed conver-partial to total). The final product is a mix- be checked before and after pelleting using sion ratio (FCR) and survival under stressfulture of cellular content and yeast cell wall. plate counts. conditions (low protein percentage andFurthermore the autolysis process degrades Despite the increasing use of yeast as crowded conditions). There is also a better Figure 4: Cumulative mortality after immersion with L. Anguiilarum (blue line is control, orange line is Figure 3: Number of pellets remaining in the feeding tray onePronady at 0.5g/kg. n=3, Pronady significantly decreases hour after feeding (n=4, YE are significantly different than mortality at 120h. P<0.01) control at P<0.05). a probiotic in terrestrial animals, there are protein efficiency ratio (PER) and digestive only a few numbers of works studying its enzyme activity when Actisaf is used. effect in fish as a gut functions stabiliser. Live yeast can be used directly on farm, The major reason is that live yeast where it has been showed (empirically) to does not resist the severe condi- improve water quality in shrimp and fish tions of the manufacturing processes ponds. It is either used alone or mixed with of aquafeeds (high temperatures, bacteria. Farms producing mash feed onsite steam, long condi- also add yeast in order to degrade cellulolytic tioning times, see material to ensure a better digestion. Aguirre-Guzzman et al 2002). The Yeast culture or fermented yeast studies are then dif- Yeast culture is a particular product in ficult to transfer from which yeast is allowed to ferment. Yeast lab conditions to farm using biomass, substrate and fermented extracel- commercial feeds. lular metabolites are then dried. All the work published so far was made with yeast Yeast extracts either top dressed on Yeast extracts (YE) come from the fur- feeds or incorporated ther hydrolysis and purification of autolysed in pressed (uncooked) yeast. Insoluble yeast cell walls are separated feeds. Nevertheless from the cellular content by centrifugation. some direct effects to YE are very soluble, rich in peptides (up to28 | January - february 2013 Grain &feed millinG technoloGy
  5. 5. Innovative and provenyeast productsin aquaculture PR A complete range LES AF OD FR UC ED SP E G IN ECIF RO ICA of natural yeast-based additives: UP FA CT OR LLY IES PR SP ODU EC CE IFI B.I. LES C D AF IN ALLY FR FA CT E GRO B.I. OR IES UP Live yeast concentrate Organic selenium yeast Premium yeast cell wall Yeast extracts P.S. AQUA P.S. Yeast cell wall NSP enzymes 500 500 to get the most from feed and promoting optimal performance for aquatic animals. Please check if the products are registered and available in your country erforma nce Wellbeing, the source of p For more information: -
  6. 6. FEATURE Figure 5: Yeast rich in organic selenium manufacturing process65%-70% of the product), free amino-acids feeding when YE are included. (Tacon and and eliminate them from the intestine. Itlike glutamic acid and vitamins. They also Suyawanish 2011). is also suspected that the mannanes act ascontain a high level of nucleic acid which can prebiotics promoting the growth of benefi-be further purified to increase the level of Yeast cell walls cial bacteria.tasty 5’ nucleotides. They are used in aquac- Yeast Cell Walls (YCW) represent the YCW have been shown to be effectiveulture in functional feeds, and hatcheries, as shell of the yeast cell and are roughly 40-50 to improve the resistance to bacterial chal-a source of nucleotides complementing the percent of the mass of the cell. YCW are lenges in numerous aquaculture novo synthesis of cells in multiplication composed mainly of fibrous polysaccharides Beta glucans have to be use carefully inand helping boost immunity and anti-stress glucans with beta 1,3 and beta 1,6 links, (50% aquaculture as some experiments report/mechanisms. and 8% respectively ), mannans under the negative effects in fish when used for Autolysed yeast and inactive yeast are form of Mannoproteins (40%) and chitin prolonged periods at high concentrations.commonly mistakenly sold under the label (2%) (see Lippke and Ovalle 1998). Further This can be avoided by careful choosing theyeast extract in aquaculture. A good way to purification can lead to the production of source of YCW and using them either atdifferentiate them is to look at the carbo- either purified beta-glucans (50% and up) high concentration (2 kg/T) only for a shorthydrate levels. Autolysed yeast has a level and mannoprotein (often used in wine mak- period, or a low concentration continuouslyaround 20-22% (mostly from the remaining ing for clarification). The presence of these (0.5 g/Kg).YCW) whereas YE contain only three to six compounds often leads to the mislabelling of An example of sea-bass juveniles fed withpercent of carbohydrates. YCW as MOS or Beta-glucans. Pronady (a YCW of the Lesaffre group) at The small peptides and free amino acids These two carbohydrate types are very 0.5 g/kg of feed for 8 weeks can be seenin YE can also prove to be a potent interesting for the aquaculture market, beta- in Figure 4, showing a significant protectionattractant for aquafeed in shrimp. In a trial glucans are direct stimulators of the immune against L. Anguillarum without any growthperformed in Thailand with white shrimp L. systems in shrimp and fish, upon the stimula- difference with the control. However avannamei. Feed containing YE at 2 kg/T of tion of specific blood cells (granulocytes or minimal amount of YCW seems neededfeed was presented in feeding trays at the macrophages). Mannans are involved in the to be ingested before challenge in ordercorner of hapas and the remaining feed was binding to pathogenic bacteria (especially to provide an efficient immunostimulationcounted after one hour. We can see a faster those with pili having mannose receptors) and so there might be a gap period when30 | January - february 2013 Grain &feed millinG technoloGy
  7. 7. FEATURE the product is not efficient. (data from Dr. alpha and beta forms)or mannans. Not associated form of selenium in the ani- Morgane Henry, Hellenic Center for marine all the YCW are equal. Efficiency should mal’s body and then allow making organic Research , 2011) be checked as a prerequisite to use, or selenium which are readily available when YCW products, depending on the quality change, YCW. oxidative stress reactions occur. of the autolysed yeast separation, contain At LFA we have conducted a survey The main application would be in aqua- also significant percentages of proteins and of four YCW (2 bakery and 2 brewery culture as fish meal is a main supply of lipids. It should be noted that the lower the yeasts) produced in 4 of our own facto- selenium and the development of diets with level of proteins, the higher of level of carbo- ries in the same L. Anguillarum challenge less fish meal will require compensation of hydrates, and then the better immunostimu- in sea bass supplemented at 0.5 g/kg selenium in aquafeed formulae. Such an lation from the YCW is. Various quality of of feed for 8 weeks. Only 2 responded application could be useful in preventing YCW are on the animal production market significantly (1 bakery, 1 brewery), the the oxidation of poly unsaturated fatty acids and major differences can be found between remaining 2 had even negative results at 4 (PUFA) in fish flesh. Chromium yeast is products depending on the strain, the sub- weeks (lower survival than control). This seldom used in aquaculture diets. strate used to produce the yeast, and event result shows first that not all is under- the drying process. stood in the way these products work Conclusion Mannans represent as most 25-27 per- and that one particular YCW cannot be Yeast products are getting more fre- cent of YCW in good quality YCW from replaced by another. quently used in aquaculture. Some appli- primary grown yeasts, but can be found cations are promising as the use as an as low as 9 percent in crude preparation Selenium yeast alternative source of proteins or as a sanitary coming from industry by-products. Glucans Yeast can be induced to be a source and welfare enhancer. However many or poly-glucose can range from 18 To 40 of organic selenium, mainly under the products ranging from crude ethanol yeast percent. YCW Protein level remains the form of seleniomethionine, which is then by-products to more purified beta-glucans most convenient indicator of quality, the stored in proteins. During the growth are available on the market. Therefore best products being those having lower of baker’s yeast, selenium is added to potential users must accurately select them nitrogen content. The variability between the medium and is replacing sulphur in in function of their targeted application. It is batches can also be very high. Texture methionine. The excess of selenium is also as important to select a reliable source should be checked first. Good YCW often then eliminated by careful washing steps of the products to ensure a consistency of have a smooth, fine texture, low granu- (see Figure 5) to ensure that the selenium the supply and the quality. lometry and a light beige colour. There is left is 97-99 percent organic. Selenium also the tendency to believe that all YCW yeast should be then checked for the More InforMatIon: are the same and that differentiation of highest percentage of selenomethionine products must be done to the highest level and the consistency between batches. Website: of glucans (sometimes measured as both Seleniomethionine is the main carbon- Offices and Factory: Ctra. de Arenas km. 2,300 13210 Villarta de San Juan • Ciudad Real- Spain T: +34 926 640 475 • F: +34 926 640 294 Madrid Office: C/ Azcona, 37 • 28028 Madrid - Spaingrain silos hoppered silos T: +34 91 726 43 04 • F: +34 91 361 15 94 Grain &feed millinG technoloGy January - february 2013 | 31
  8. 8. Milling Technology magazine. Content from the magazine is available to view free-of-charge, both as a full LINKS This digital Re-print is part of the January | February 2013 edition of Grain & Feed online magazine on our website, and as an archive of individual features on the docstoc website. Please click here to view our other publications on January - February 2013 first published in 1891 • See the full issue • Controlling the explosion risks within hammer mills • Visit the GFMT website • • Contact the GFMT Team Recycling surplus factory food In this issue: into quality animal feeds • Efficient barge unloading technology • Use of computer • Feed • Subscribe to GFMT programming enzymes in animal diet in animal formulation nutrition INCORPORATING PORTS, DISTRIBUTION AND FORMULATION A subscription magazine for the global flour & feed milling industries - first published in 1891 To purchase a paper copy of the magazine, or to subscribe to the paper edi- tion please contact our Circulation and Subscriptions Manager on the link adove. INFORMATION FOR ADVERTISERS - CLICK HERE Article reprints All Grain & Feed Milling Tecchnology feature articles can be re-printed as a 4 or 8 page booklets (these have been used as point of sale materials, promotional materials for shows and exhibitions etc). If you are interested in getting this article re-printed please contact the GFMT team for more informa- tion on - Tel: +44 1242 267707 - Email: or visit