May | June 2012

Feature title: Brewers’ yeast as a supplement in aquaculture

The International magazine for the aquaculture feed industry

International Aquafeed is published five 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 of information published. ©Copyright 2012 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

The effect of stress caused by envi-ronmental pollution and farming conditions on the health and yield of fish in intensive aquacultures is

becoming increasingly important.

Factors such as stocking density, con-tamination, toxins, pollutants and outbreaks of disease have a negative effect on the immune status of the fish. The consequence of this is an increased susceptibility to infection through bacterial, viral, fungal or parasitic pathogens. Increased loss rates and reduced growth performance result in lower profitability for the fish production industry.

As a consequence, the monetary and

quantitative overheads for the vaccination and medicinal treatment of the fish increases. In many cases, antibiotics are given not only therapeutically, but also prophylactically as a standard additive in fish feed.

The intensive farming methods used for fish cultivation in aquatic environments with a direct connection to the groundwater are especially liable to facilitate the very rapid and direct spread of problematic production residues to humans. Resistant pathogens and germs do not just limit the effectiveness of

therapeutic antibiotics for fish. The transfer of genes for resistance between different spe-cies of bacteria is accelerated, leading to an exacerbation of the problem of resistance in the treatment of human diseases worldwide.

Future-oriented production methods in the fish farming industry should therefore be targeted towards minimising the use of antibiotics and medicinal drugs. It is of great importance to analyse the negative effects caused by environmental pollution and farm-ing methods.

More crucial still will be to influence the animal's metabolism so that external toxins have a lesser impact, even under intensive conditions. A healthy gut and a functioning

non-specific immune response are fundamen-tal prerequisites for this.

Excellent for the gutBrewers’ yeast cells are like miniature

power houses, and are responsible for the alcoholic fermentation that takes place during the brewing stage of beer production. In the course of the fermentation of malt extract, high concentrations of minerals and trace elements, amino acids and nucleotides, B vitamins and enzymes, as well as many micro-

nutrients accumulate within the cells of the yeast species Saccharomyces cerevisiae. Being organically bound ensures high availability of these active substances. Dried brewers’ yeast is used very often in fish nutrition due to the high bioavailability of the constituent compounds.

In addition to this, brewers’ yeast has cell walls that are composed of mannan-oligosaccharides (MOS). This complex net-work of mannans and ßglucans serves as a substrate for the beneficial gut flora. The fish's limited digestive tract benefits in particular from the prebiotic properties of the yeast cell walls, which stabilise the gut and ensure a healthy balance of microflora

(eubiosis). In addition to this, the mannan-oligosaccharides in brewers’ yeast are able to bind harmful toxins in the food, and thus inhibit their absorption and resultant metabolic harm. Last but not least, the for-mation of a biofilm on the intestinal mucosa enhances this protective barrier against pathogens.

Glucan and the immune systemThe cell wall of brewers’ yeast com-

prises approximately 20-25 percent mannans

Brewers’ yeast as a supplement in aquaculture

by Jan Frericks, Leiber GmbH, Germany

"The cell wall of brewers’ yeast comprises approximately 20-25%

mannans and 25-30% ß-glucans. ß1,3/1,6(D) glucan molecules can

be isolated from it using special hydrolytic processes. The molecules

consist of characteristic (1,3)-beta-glycosidic linked D-glucose

subunits connected with with irregular beta-(1,6)-linked side chains of

various length. Only this free ß-glucan structure from Saccharomyces

cerevisiae has an immunomodulatory effect on the metabolism"

40 | InternatIonal AquAFeed | May-June 2012

FEATURE

IAF12.03.indd 40 14/05/2012 18:08

Volume 15 / Issue 3 / May-June 2012 / © Copyright Perendale Publishers Ltd 2012 / All rights reserved

WHO CARES...…If profits in the aquaculture industry are as appetising as a sea bass dinner?

As feed prices soar and formulation moves towards sustainability, aquaculture producers must maximise feed efficiency to stay on the menu.

In all phases of the fish’s life, proper nutrition will improve health. With decades of dedicated research, the “Alltech Aqua Advantage” programme responds to the challenges of today’s aquaculture producers

through nutritional innovation, addressing issues such as growth and performance, feed efficiency, flesh quality and immunity.

So, when asked who cares about your profitability? Remember

DOES!

alltech.com | facebook.com/AlltechNaturally | @Alltech

Silver Sponsor of

XV International Symposium on Fish Nutrition and Feeding

Molde, Norway • 4-7 June 2012

IAF12.03.indd 2 14/05/2012 18:05

and 25-30 percent ß-glucans. ß1,3/1,6(D)glucan molecules can be isolated from it using special hydrolytic processes. The molecules consist of characteristic (1,3)-beta-glycosidic linked D-glucose subunits connected with with irregular beta-(1,6)-linked side chains of various length. Only this free ß-glucan struc-ture from Saccharomyces cerevisiae has an immunomodulatory effect on the metabolism.

In contrast with intact yeast cells or man-nan-oligosaccharides, free ß1,3/1,6(D)glucan molecules are able to pass through the pro-tective epithelial barrier in the gut with the help of specialised M cells. In gut-associated lymph tissue (GALT), ß-glucans act like anti-gens, stimulating specific macrophage recep-tors with their characteristic surface structures (epitopes) (Engstad and Robertsen 1993). A cascade of immune responses is triggered, and non-specific immune system cells such as monocytes, natural killer cells, B-cells, T-cells or lysozymes are released or activated. They put the animal on a high state of alert and preparedness to defend against all types of foreign attack. What differentiates this from an actual infection is that ß-glucan does not possess any pathogenic properties, and acts without causing any adverse health effects.

A quality criterion for the effectiveness of

ß-glucan products is not only the source and characteristic molecular structure, but also the purity of the product. A minimum content of 70 percent pure ß1,3/1,6(D)glucan should be aimed for. The standard grade Leiber® BetaS has a ß-glucan content of 80 percent. The met-abolic activity of this product has already been tested on many animal species and verified.

Tests were recently performed on sev-eral species of fish that confirm a stimulatory effect on the non-specific immune system. Rainbow trout and carp received 0.02 percent ßglucan (Leiber® BetaS) administered in their feed ration. The potential killing activity of phagocytes, the proliferative response of T and Blymphocytes and the concentration of immunoglobulins and lysozymes in the blood serum was measured four weeks and eight weeks after beginning administration. In two repetitions, a significant stimulation of these parameters was demonstrated in both rain-bow trout and carp.

In subsequent infection studies using two bacterial (Aeromonas salmonicida; Yersinia ruckeri) and one viral pathogen (IPN virus), the survival rate of rainbow trout and carp with 0.02 percent Leiber® BetaS in their feed showed an absolute increase of 30-40 percent (Siwicki, et al. 2008; Siwicki, et al. 2009).

Oral administration testsPurified ß1,3/1,6(D)glucans enhance the

animals' non-specific immune response. This is of particular value in the fish farming industry, as there are multiple stress and environmen-tal factors that impact and stress the fish. If they become infected, the specific immune system is only able to respond slowly and inadequately. In such situations, a heightened non-specific capability can support or acceler-ate the specific immune response and the production of specific antibodies.

Fish are subject to similar, added stresses during vaccinations too. A study by Siwicki et al. (2011) investigated the effect of orally administered ß1,3/1,6(D)glucan (100mg or 200mg Leiber® BetaS per kg of feed) on the antibody secreting cells (ASC) and specific antibody titres after immunisation of rainbow trout fingerlings (Oncorhynchus mykiss) by immersion with anti-enteric redmouth disease vaccine (AquaVac ERM). Inoculation was per-formed one week after the start of administra-tion with Leiber® BetaS.

These two parameters were measured on day seven, 14, 21, 28 and 40 in the blood serum and adrenal glands. Both dos-age levels stimulated the number of specific ASCs and specific antibody levels, whereby 0.02 percent Leiber® BetaS in the fish feed was more effective. In each case the improvements were significant from day 21 onwards.

The beneficial effect of ß1,3/1,6(D)glucan is well known in the fish nutrition industry. The administration of 0.02 percent Leiber® BetaS in fish feed activates the non-specific immune status of the fish on the one hand, and on the other, acts as an adjuvant during vaccina-tions, thus enhancing the immunocompetence of the fish. Its safe and simple method of use, as well as the fact that ß-glucan from Saccharomyces cerevisiae is harmless to fish and the environment, will become yet more important in the future. ■

Tests were recently performed

on several species of fish that

confirm a stimulatory effect on the

non-specific immune system

42 | InternatIonal AquAFeed | May-June 2012

FEATURE

May-June 2012 | InternatIonal AquAFeed | 43

IAF12.03.indd 42 14/05/2012 18:08

and 25-30 percent ß-glucans. ß1,3/1,6(D)glucan molecules can be isolated from it using special hydrolytic processes. The molecules consist of characteristic (1,3)-beta-glycosidic linked D-glucose subunits connected with with irregular beta-(1,6)-linked side chains of various length. Only this free ß-glucan struc-ture from Saccharomyces cerevisiae has an immunomodulatory effect on the metabolism.

In contrast with intact yeast cells or man-nan-oligosaccharides, free ß1,3/1,6(D)glucan molecules are able to pass through the pro-tective epithelial barrier in the gut with the help of specialised M cells. In gut-associated lymph tissue (GALT), ß-glucans act like anti-gens, stimulating specific macrophage recep-tors with their characteristic surface structures (epitopes) (Engstad and Robertsen 1993). A cascade of immune responses is triggered, and non-specific immune system cells such as monocytes, natural killer cells, B-cells, T-cells or lysozymes are released or activated. They put the animal on a high state of alert and preparedness to defend against all types of foreign attack. What differentiates this from an actual infection is that ß-glucan does not possess any pathogenic properties, and acts without causing any adverse health effects.

A quality criterion for the effectiveness of

ß-glucan products is not only the source and characteristic molecular structure, but also the purity of the product. A minimum content of 70 percent pure ß1,3/1,6(D)glucan should be aimed for. The standard grade Leiber® BetaS has a ß-glucan content of 80 percent. The met-abolic activity of this product has already been tested on many animal species and verified.

Tests were recently performed on sev-eral species of fish that confirm a stimulatory effect on the non-specific immune system. Rainbow trout and carp received 0.02 percent ßglucan (Leiber® BetaS) administered in their feed ration. The potential killing activity of phagocytes, the proliferative response of T and Blymphocytes and the concentration of immunoglobulins and lysozymes in the blood serum was measured four weeks and eight weeks after beginning administration. In two repetitions, a significant stimulation of these parameters was demonstrated in both rain-bow trout and carp.

In subsequent infection studies using two bacterial (Aeromonas salmonicida; Yersinia ruckeri) and one viral pathogen (IPN virus), the survival rate of rainbow trout and carp with 0.02 percent Leiber® BetaS in their feed showed an absolute increase of 30-40 percent (Siwicki, et al. 2008; Siwicki, et al. 2009).

Oral administration testsPurified ß1,3/1,6(D)glucans enhance the

animals' non-specific immune response. This is of particular value in the fish farming industry, as there are multiple stress and environmen-tal factors that impact and stress the fish. If they become infected, the specific immune system is only able to respond slowly and inadequately. In such situations, a heightened non-specific capability can support or acceler-ate the specific immune response and the production of specific antibodies.

Fish are subject to similar, added stresses during vaccinations too. A study by Siwicki et al. (2011) investigated the effect of orally administered ß1,3/1,6(D)glucan (100mg or 200mg Leiber® BetaS per kg of feed) on the antibody secreting cells (ASC) and specific antibody titres after immunisation of rainbow trout fingerlings (Oncorhynchus mykiss) by immersion with anti-enteric redmouth disease vaccine (AquaVac ERM). Inoculation was per-formed one week after the start of administra-tion with Leiber® BetaS.

These two parameters were measured on day seven, 14, 21, 28 and 40 in the blood serum and adrenal glands. Both dos-age levels stimulated the number of specific ASCs and specific antibody levels, whereby 0.02 percent Leiber® BetaS in the fish feed was more effective. In each case the improvements were significant from day 21 onwards.

The beneficial effect of ß1,3/1,6(D)glucan is well known in the fish nutrition industry. The administration of 0.02 percent Leiber® BetaS in fish feed activates the non-specific immune status of the fish on the one hand, and on the other, acts as an adjuvant during vaccina-tions, thus enhancing the immunocompetence of the fish. Its safe and simple method of use, as well as the fact that ß-glucan from Saccharomyces cerevisiae is harmless to fish and the environment, will become yet more important in the future. ■

Tests were recently performed

on several species of fish that

confirm a stimulatory effect on the

non-specific immune system

42 | InternatIonal AquAFeed | May-June 2012

FEATURE

May-June 2012 | InternatIonal AquAFeed | 43

IAF12.03.indd 42 14/05/2012 18:08

42 | InternatIonal AquAFeed | May-June 2012 May-June 2012 | InternatIonal AquAFeed | 43

FEATURE

AquaStar®Fast growth in improved environment!Probiotic strains to support gut health. Biodegrading strains and enzymes to stabilize water quality and pond bottom.

aquastar.biomin.net

Naturally ahead

to stabilize water quality and pond bottom.

• Improvedguthealth andperformance• Improvedwaterquality

• Controlofpathogenic

bacteria

IAF12.03.indd 43 14/05/2012 18:08

www.aquafeed.co.uk

LINKS

• Seethefullissue• VisittheInternationalAquafeedwebsite

• ContacttheInternationalAquafeedTeam

• SubscribetoInternationalAquafeed

VOLUME 15 I S SUE 3 2 012

THE INTERNATIONAL MAGAZINE FOR THE AQUACULTURE FEED INDUSTRY

Transfering Vitamin C from fish to embryos

Oxygenation technology– poised to transform aquaculture worldwide

Ornamental fish and invertebrates for home aquaria

Brewers’ yeast as a supplement in aquaculture

IAF12.03.indd 1 14/05/2012 18:05

Thisdigitalre-printispartoftheMay|June2012editionofInternationalAquafeedmagazine.Contentfromthemagazineisavailabletoviewfree-of-charge,bothasafullonlinemagazineonourwebsite,andasanarchiveofindividualfeaturesonthedocstocwebsite.Pleaseclickheretoviewourotherpublicationsonwww.docstoc.com.

Topurchaseapapercopyofthemagazine,ortosubscribetothepapereditionpleasecontactourCirculationandSubscriptionsManageronthelinkabove.

INFORMATIONFORADVERTISERS-CLICKHERE