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Probiotics and Shrimp Farming

 

This discussion, which occurred on the Shrimp List during the last quarter of 2004, broadly defines “probiotics” as live  bacterial supplements that improve animal health.  They are used in shrimp feeds, hatcheries and growout ponds.  The discussion starts with a question about the carbon/nitrogen ratio in Penaeus monodon ponds.

 

Peter Van Wyk, an aquaculture project planning specialist at Harbor Branch Oceanographic Institution in Florida, USA, and also the author of a manual on low-salinity, inland shrimp farming, gets the discussion going with a very informative answer to the carbon/nitrogen question.

 

Once the List answers the C:N question, it jumps into a long discussion of probiotics, resolves a minor squabble about commercialism on the List and generally demonstrates what a good discussion is all about.

 

Contact information on the participants appears at the end of this report.  One of the participants, Dr. Vasudevan, an aquaculture consultant and managing director of Hi-Line Aqua, which supplies feeds and equipment to shrimp farms in India, after reviewing a draft of the report, forwarded an number of additions.  His additions appear in italics.

 

Sunil Kant Verma, a former employee of Hi-Line Aqua in India, started the discussion with the following question: Could someone give me information on the carbon/nitrogen ratio in Penaeus monodon ponds?

 

Peter Van Wyk, aquaculture project planning specialist at Harbor Branch Oceanographic Institution in Florida, USA, responded:

 

Probiotic bacterial cultures added to shrimp ponds typically are composed primarily of heterotrophic bacteria, or a mixture of heterotrophic bacteria and autotrophic nitrifiers.  Heterotrophic bacteria are those bacteria that primarily obtain their nutrition from organic sources.  The primary source of carbon for these bacteria is carbohydrates.  Nitrogen is typically obtained from the proteins in the organic material consumed by the bacteria.  Just like the shrimp, heterotrophic bacteria excrete ammonia as a by-product of the metabolism of the proteins they consume.  Some heterotrophic bacteria, however, are able to utilize ammonia directly as an alternative source of nitrogen.

 

Well what does this all have to do with C:N ratios?  Shrimp feeds used in intensive shrimp ponds typically have at least 35% protein.  These feeds do not contain a lot of carbohydrate.  C:N ratios in these feeds typically run around 9:1.  The bacteria require about 20 units of carbon per unit of nitrogen assimilated.  With such a low C:N ratio in the feed, carbon is the limiting nutrient for heterotrophic bacteria populations.  The bacterial population will not expand beyond a certain point due to the limited availability of carbon.  The protein in the organic detritus supplies most of the nitrogen requirement for the heterotrophic bacteria under these circumstances, and inorganic ammonia is not utilized as a nitrogen source to any great extent.

 

If the C:N ratio is increased, either by feeding lower protein feeds with a higher percentage of carbohydrate, or by adding a carbohydrate source such as molasses in addition to the regular feed, the increased availability of carbon allows the heterotrophic bacterial population to consume a higher percentage of the protein in the organic material.  This results in more complete digestion of the organic material in the pond by the heterotrophic bacteria.  As the C:N ratio increases, the heterotrophic bacteria resort increasingly to ammonia metabolism to meet their nitrogen requirements.  As C:N ratios are increased even further, a point is reached where nitrogen, rather than carbon, becomes the limiting nutrient.  At this point ammonia concentrations should be close to 0 mg/L in the pond.

 

It should be pointed out that holding the feed protein constant and supplementing with pure carbohydrate will result in much higher bacterial counts in the pond.  The oxygen required to support this additional bacterial biomass will increase proportionally with the increase in bacterial population.  Likewise, CO2 production will increase, driving pH down.  If you are contemplating carbohydrate supplementation to increase C:N ratios, make sure that your pond is well-aerated and circulated to keep the organic detritus suspended in the water column where there is sufficient oxygen for the heterotrophs.  Also, once you develop a dense population of heterotrophs through carbohydrate supplementation, don’t discontinue the carbohydrate supplementation suddenly.  This will starve the bacteria of carbon, a die-off will occur and you will get an ammonia spike.

 

Another point that should be considered before enhancing C:N ratios in P. monodon ponds.  P. monodon does not utilize the organic detritus and associated bacterial protein as effectively as a food source as does P. vannamei.  With vannamei, C:N ratios can be enhanced by lowering the overall feed protein levels and utilizing feeds that are high in carbohydrate.  Because vannamei feeds on the organic flocs and utilizes bacterial protein efficiently, growth rates don’t suffer and protein utilization efficiencies improve dramatically.  With monodon, feeding low-protein, high-carbohydrate diets will likely result in lower growth rates.  Therefore it might be necessary to rely more on supplementation with pure carbohydrates to boost C:N ratios.  But this will result in more bacterial biomass, more BOD and higher CO2.  This makes it somewhat questionable, in my mind, whether it is worth the risk to manage a monodon pond with high C:N ratios.

 

Claudio Paredes, aquaculture business development manager for Agribrands Purina in Venezuela: Excellent description.  Do you seed the pond with bacteria, or are they already there?

 

Peter Van Wyk: Probably the most common genera of heterotrophic bacteria used in probiotic formulations are Bacillus and Lactobacillus, both of which are gram-positive.  It is not necessary, however, to inoculate a pond with commercial probiotics in order to manage a heterotrophic production system.  This can be accomplished simply by maintaining a C:N ratio greater than 12:1, and supplying adequate aeration.  The bacteria are already present in every pond.  By removing the carbon (and perhaps oxygen) limitation, they will proliferate.

 

I’m a bit skeptical about the value of probiotic treatments in ponds.  The counts of naturally occurring bacteria are several thousand per milliliter, so a one hectare pond contains astronomical amounts of bacteria.  It would be very difficult to add enough bacteria to a pond to significantly change its bacterial composition.  (Vasudevan: Bacillus bacteria multiply in 0.32 to 2 hours after inoculation.)

 

Also, one might expect that the naturally occurring bacteria species are the best adapted to the conditions in the pond.  There is no guarantee that the bacteria in the probiotic culture will be well adapted to the conditions in the pond, let alone that they will out-compete the naturally occurring bacteria species.  Even if enough bacteria were added to have an effect on bacterial composition at one point in time, it would likely be necessary to re-inoculate the bacteria periodically to maintain the predominance of the probiotic species.  I admit that there have been studies which appear to show benefits in terms of survival in probiotic treated ponds.  But there are also a lot of studies that fail to find any measurable impact on bacterial species composition.  Perhaps there is something going on that enables the probiotic bacteria to positively influence survival even when they are not the predominant species.

 

I am, however, a big fan of probiotic usage in hatcheries.  In that situation you are starting off with sterile seawater, and it is possible to add a much higher number of bacteria per unit volume of water.

 

Claudio Paredes: Bacillus and Lactobacillus are common genera of heterotrophic bacteria used in probiotic formulas.  What genera of the heterotrophic bacteria are already in the ponds, but not in the commercial probiotic products?

 

(Vasudevan: Marine soil sediments contain naturally occurring beneficial bacteria such as Bacillus subtillis,B. circulans, B. megaterium, B. polymyxa, and B. licheniformis.  They are purified and multiplied in fermenters and then further processed as liquids or spray-dried powders for marketing in vegetative or spore forms).

 

Also, what’s the best way to measure the C:N ratio in a pond?

 

Dallas Weaver, owner of Scientific Hatcheries, in California, USA, which markets bacteria that remove hydrocarbons from soils: Measurement of C/N is only part of the story.  If you measure TOC (total organic carbon), some of that carbon can be refractory and not help grow bacteria and soak up the ammonia.  Measuring TOC and BOD (biological oxygen demand, with and without ammonia oxidation inhibition) along with TKN (total Kjeldahl nitrogen) will provide some useful management information.  To make these systems work, you should also be rearing a species that can use the single-cell protein being produced in the pond.  If not, all you are doing is converting ammonia into an unusable biomass using a significant amount of carbohydrate and oxygen.  You either have to discharge that biomass or oxidize it in the pond bottom when drained.  If it stays in the system, it will metabolize itself back into ammonia and CO2.

 

The only difference between a photosynthetic system (algae in a pond) and a heterotrophic system (carbohydrate and oxygen) is the energy supply for the waste treatment function.  Sunlight limits your energy density per unit area in algae-based systems, which limits your feed/area.  With heterotrophic systems the energy density is not limited; it’s volumetric.

 

The real trick is to get the biomass from these waste systems into a usable animal as fast and efficiently as possible so you don’t waste energy redoing the ammonia again and again as the biomass (or algae) you produced with your energy input decays.

 

Remember: all closed aquaculture is polyculture.  The only question is how many sellable species do you have and what are your energy flows.  The job of an aquaculturist is to control that microbiological ecology to get the energy flows and treatment biomass to go where you want.

 

Kevin Healey, a supplier of probiotics from Australia: This has been an interesting discussion on C:N ratios, and thanks to Peter for the time he’s taken to provide such clear explanations.  I’m in agreement with pretty much all he’s stated, in particular the usefulness of molasses in promoting a heterotrophic bacteria bloom in ponds, and the value of using probiotics in hatcheries.

 

I would like to argue the case for using probiotics in shrimp ponds, especially when carbon addition is practiced.  Shrimp ponds develop a bacterial bloom whose growth is largely dependent on the main carbon sources of uneaten feed and feces.  Often this is aided at fill-time by the use of manure to initiate the pond bloom.  As Peter explained, you can enhance the heterotrophic bacterial component of the bloom further through addition of more carbon.  The characteristics of the bacteria that dominate these blooms, however, can be a bit of a lottery; for example, some of our customers have high levels of luminescent Vibrio in the seawater they bring in to fill their ponds.  David Moriarty has done plenty of work to show that Bacillus probiotics can be used to improve pond health, even when they aren’t the dominant bacterial species present.  They will accelerate breakdown of organic matter (especially the particulate matter that settles to create black sludge) and actively suppress luminescent Vibrio.  Yes, you need to make weekly application of the probiotics.

 

Peter mentioned that sometimes probiotics in ponds have failed to deliver on their promises.  The keys to successful use in ponds include: choosing products with a proven track record and understanding that much of the work that probiotics do is about providing a low stress environment.  This means that the microbes used must be active in the water column as well as in the animals’ guts.  Probiotics are not a “magic cure” for any and all problems.  Rather, they are a powerful tool to be used as part of an overall program of management, which will deliver the results you want provided the entire program is followed with diligence.

 

Antonin Jamois, assistant manager of a shrimp farm in Madagascar: Have any of you tried probiotics in large, semi-intensive ponds without aeration?

 

What do you think about “chaining” the bottom during the probiotic application?  Does it help the probiotic do its work?

 

If probiotics have to be used once in a week, what’s the basic treatment in kilograms per hectare?

 

I fully agree with Kevin about the importance of choosing the right product.  Do you know of any probiotics for semi-intensive ponds?

 

Dr. S. Vasudevan, an aquaculture consultant and managing director of Hi-Line Aqua, which supplies feeds and equipment to shrimp farms in India: David Moriarty has done excellent work to eliminate Vibrios through competitive exclusion and by killing them directly.  He has also proven that probiotics clear Vibrios from the animal guts, especially at the hatchery level.  We saw very clearly that the Vibrio counts, including green and luminous Vibrios, dropped daily when we doubled the dosage of probiotics in our larval feeds.

 

We have been using probiotics in shrimp ponds with and without aeration for a long time.  In semi-intensive ponds, a minimum of 1,000 colony forming units of Bacillus per milliliter is required.

 

(Vasudevan: Almost all feed companies in India have been supplying some or other probiotics and strongly recommend their usage in shrimp ponds in water, soil and also in feeds.  It appears that there is no aquaculture in India without probiotics which has led to almost total elimination of antibiotics that produce resistance and  more virulent vibrios.)

 

Bob Rosenberry, editor and publisher at Shrimp News International in California, USA: “Several replicated pond studies conducted over the past 20 years at Auburn University and Mississippi State University in the United States did not demonstrate improvements in sediment and water quality in ponds treated with bacterial inocula and enzymes.”

 

“Even at doses several times the treatments suggested...the amendments did not cause positive changes in water quality in lab systems.”

 

Source: The Global Aquaculture Advocate (www.gaalliance.org).  Probiotics enhancement of soil, water quality examined.  Claude Boyd (Ph.D., Professor, Department of Fisheries and Allied Aquacultures, Auburn University Auburn, Alabama 36849, USA, email boydcel@auburn.edu).  Volume 7, Issue 2, P-32, April 2004.

 

Peter Van Wyk: With respect to questions about which species of heterotrophic bacteria are already present in shrimp ponds, I can only say that it is a very long list.

 

To say that a bacteria is “heterotrophic” only says that it derives its nutrition primarily from organic sources.  Common heterotrophic bacteria in shrimp ponds include both beneficial genera (Bacillus, Lactobacillus) and pathogenic genera (Vibrios).  Bacillus is often a dominant species.  The bacteria in probiotic preparations do occur naturally in ponds.

 

Measurement of C:N ratios in ponds is not a simple task because the carbon and nitrogen end up in a lot of different places: the feces, the organic floc, the bacteria, the water and the shrimp.  Researchers use labeled isotopes of carbon and nitrogen in the feed to study C:N budgets in ponds.  Of course this isn’t practical in a production pond.  Managing the C:N ratio in a pond is handled more easily by managing the C:N ratio of your feed.  I estimate the C:N composition of the feed rather than measure it.  I don’t have access to laboratory equipment to measure total organic carbon and total Kjeldahl nitrogen, nor do I have the budget to send out samples to a laboratory for analysis.

 

Carbon accounts for roughly 50% of the dry weight of most feeds.  This is a crude estimate, but carbon content is remarkably constant even for feeds with widely varying compositions.  The nitrogen content of the feed is calculated from the protein content.  Protein is approximately 16% nitrogen.  Although this method for calculating C:N ratios is admittedly crude, it provides a reasonably close estimate of actual C:N ratios.

 

Juan Carlos Quintana, with Maricultura del Pacifico, a shrimp farm in Mexico: Could anyone tell me if wheat flour would be a good source of carbon to obtain the right C/N ratio in a heterotrophic system.  I have used sugar with good results, but it’s more expensive than wheat flour.

 

Adam Body, a shrimp farmer in Australia: We tried wheat flour last year, and compared it to molasses: my strong suggestion is to stay with molasses, which is what we have done after analyzing the results of our experiments.

 

We also use molasses plus probiotics in our hatchery...same set of principles as being discussed on the List.  We compared tanks with and without probiotics.  The “withs” had no luminescence, the “withouts” had luminescence.

 

Dallas E. Weaver: You can look at the microbiological ecology of one of these shrimp system from the point of view of relative biomass and metabolism.  When you add shrimp feed to the pond, only a fraction of that feed is converted into shrimp biomass—on the order of 10% (on a dry weight basis) with another 20% or so being metabolized by the shrimp and the balance being handled by the rest of the pond ecology or flushed with water changes.  The yield coefficient of some of the decomposing bacteria is quite favorable, which means we can grow several times as much bacterial biomass as shrimp biomass.  That bacterial biomass can then be consumed by other bacteria, protozoans and larger organisms in the pond.  With each transfer in that microbiological food chain, biomass is lost.  Algae get into the game by using nutrients from the shrimp and the microbial food chain.  The algae eventually enter the decomposition food chain—or if we are clever, enter a floc that the shrimp consume—before decomposing in the food chain.

 

What this means is that the relative size and metabolism of this microbiological decomposition food chain is greater than the shrimp biomass in the pond and its food consumption is comparable to the feed rate of the pond, plus algae productivity.  This relative size makes me question the impact of a few kilos of bacteria per week on a system that is getting 50-100 kilos of feed per hectare per day.

 

Unless you are near ecological instability, a few kilos of non-optimized bacteria are irrelevant (which is why replicated studies don’t show anything).  Perhaps a better solution is to take some sludge from the pond that is working best and add it as seed culture to the ponds that are not performing.  As you are just using this sludge for microbiological decomposer seed, you may want to let it sit for many months with aeration and let any potential shrimp pathogens die.

 

We are all in the business of growing bacteria with a secondary crop that we sell to pay the bills.

 

PS: It takes a lot more than one species of bacteria to decompose mixed wastes.  It usually takes thousands.  We don’t have waste that consists of one group of chemicals that can be handled with one bacteria species.  For example, my MTBE eating bacteria can handle MTBE, TBA, formaldehyde, ethanol, methanol, and a few other things including ether bonds, but it doesn’t do well on BTEX (benzene, Toluene).

 

Anthony Xavier: Can any species of Bacillus be used in combination with Lactobacillus species as a feed probiotic?  If so please provide some details.

 

B. Suryakumar, president of Hitide Seafarms in India: We have been using molasses quite successfully to keep the afternoon pH below 8.5.  This must be due to the additional carbon dioxide produced by the bacteria.  We were also hoping that the bacteria would compete with the phytoplankton for the ammonia and the diurnal variation of pH would be limited.  Even in ponds with a total alkalinity of around 200, we see daily pH variations exceeding 0.5.  Any comments?  (Vasudevan: Addition of food grade dyes control algal blooms, freeing more carbon and controlling pH.)

 

 

Dallas E. Weaver: Using molasses to provide the CO2 to keep the pH down is fine.  Note, however, that the addition of molasses will increase the nighttime oxygen demand for respiration by the bacteria.  Adding more bacteria to an algae-based system can create flocculation conditions—a little of which is good if the shrimp are feeding on the floc or bad if all the algae and bacteria settle on the bottom creating an anaerobic bottom.  It all depends upon mixing energies and the details of the system and its operation.  It’s an “art”; science only provides the broad outlines.

 

The magnitude of the pH swing will be a function of the total amount of alkalinity per unit area, the amount of sunlight, mixing and nutrients.  Shallow waters can have daily pH swings of more than 1 pH unit.  You can get a pH greater than 10, which is good for killing many pathogens.

 

I believe the best solution to the diurnal pH and O2 swing problem is deeper ponds.  This will give you more alkalinity/area and more water volume to store the high O2 during the day for use at night—assuming you have enough mixing energy to prevent stratification during the day.  This will increase the capital cost of the ponds, but decrease the energy consumption per kilo of production and decrease the pH stress on the animals.

 

Increasing the alkalinity will also decrease the pH swing, while increasing the average level of pH.  Going from 200 to 300 CaCO3 alkalinity may pay in terms of smaller pH swings and less stress on the animals with only a small average pH increase.

 

G. Vijayaraghavan: The following species are used as feed probiotics:

 

Bacillus acidophilus

Lactobacillus delbruckii

L. bulgaricus

B. subtilis

B. megaterium

Acetobacter xylinum

B. lechiniformis

Saccharomyces cerevesiae [fungus, yeast]

Saccharomyces boulardii [fungus, yeast]

 

Kevin Healey: You can find out more about probiotics for your application by visiting my website (www.iahp.com.au).  When the home page opens select “International” and then “Aquaculture”, where you will find links to our product data sheets and application bulletins.  For information about adapting the probiotic application to your specific farm, please contact me offline, and I’d be happy to go through it with you.

 

In general, Bacillus are great bacteria for use as probiotics because they produce a wide variety of degradative exoenzymes, because they can be distributed in the form of spores, which are very robust and are likely to arrive in healthy condition at your farm, and because they can survive processing into feed.

 

You don’t want just any Bacillus strain.  You want strains that are nonpathogenic, that will actively suppress pathogens like Vibrio, that are adapted to marine environments, and that have been proven in the field.  If you work with a reliable supplier of probiotics, they will take care of this for you.

 

Much of the work that these organisms do is accomplished in the water column, where they breakdown sludges and slimes that exude toxic substances and harbor pathogens.  They are also active in the animal’s gut, suppressing pathogens and assisting the digestion of feed.

 

Lactobacillus are basically gut microbes and should be included in feeds.  The real problem is that they are rather delicate and are often killed when processed.

 

The best way to use probiotics is to start right at the beginning, when the pond is filled and before it is stocked.  Then provide a regular weekly top-up application and there should be sufficient probiotic activity to meet your needs.

 

The strains you list can indeed be used as probiotics; however, most of them should be applied in the feed.  Also they tend to be rather delicate and may lose potency during processing.

 

The Bacillus organisms are different because they can be supplied as spores, which are much more robust.  They are active in the water column and can be applied directly to the water or in the feed.  You should choose proven strains of Bacillus from a reliable manufacturer.

 

Claude Boyd’s article doesn’t actually give any of the trial details, and his conclusion is simply that the products he tried didn’t work.  In fact, he also refers to published trials where probiotics were successful and goes on to encourage people to try probiotics in their ponds.

 

Eluri Apuchand, chief operating officer at Vintech in India: Use the Bacillus strains that are lactic-acid-producing and spore-forming as feed probiotics.  Non-lactic acid producing Bacillus sporogenes don’t work as feed probiotics.

 

Pablo Legarda: Will adding spores to the feed work?  Since shrimp don’t always start feeding immediately, will the spores dissolve into the water column before the shrimp get to them?  How many spores per gram of feed are recommended?  How do we know the spores are alive?  Are the spores isolated from shrimp ponds?

 

Kevin Healey: Many of our customers simply germinate the spores on the day of use and then soak them into the pellets (often in a concrete mixer) before feeding.  You can add as much as you like, up to the point that the pellets stick together when squeezed.

 

Bacillus are very hardy and are typically isolated from aquatic environments or soil.  Their origin isn’t as important as their effectiveness.  The main point is to choose strains that have been proven to be effective in shrimp ponds and hatcheries.

 

Paul Smith, a senior lecturer at the University of Western Sydney in Australia: Dear Kevin, you are continuing to push your probiotic products on our site.  Enough is enough.

 

Leonido C. Tala, project manager at a big semi-intensive shrimp farm in Madagascar: I am not against this new innovation which could give all of us a big advantage in the future, but I don’t think it’s fair for the sellers of probiotics to dominate the discussion.

 

Why don’t the probiotic salesman just supply a list of satisfied shrimp farmers, along with their testimonies on the successful use of the product.  (Vasudevan: We can testimonials on the successful  performance of probiotics.)

 

As Dr. Paul Smith said, enough is enough, and I call on the moderator to restore order to the list.

 

Phil Boeing, a shrimp farming consultant in California, USA: A few comments on the last posting: A previous discussion on the List was far more commercial than this one, but even it was fueled by farmers wanting to know about the subject.  Gentlemen—that’s why there is a chat line.  To chat.  If the sellers come on without invite then it is spamming and against the rules, but if the questions are answered in a direct dialog then where is the beef?

 

Dan Fegan, formerly with Thailand’s National Center of Genetic Engineering and Biotechnology and now Regional Technical Manager of Aquaculture for Alltech Biotechnology Corp., Ltd., in Thailand—and the creator of the Shrimp List—adds: While I agree with Leonardo that the information from the probiotics marketers does not really add much to the quality of the discussion, I haven’t found it to be overt advertising either.  Most of us are sensible enough to evaluate the worth and quality of the information offered and make our judgments accordingly.  The level of scientific detail and logic of some of the postings on the management of the microbial environment and C:N ratio make the claims and counter claims on behalf of probiotics for shrimp ponds look rather meager (although I do agree that there is a far more realistic role for them in hatcheries).  What I would say is that anyone making repeated marketing pitches might actually be putting people off rather than attracting business.

 

Ramon Macaraig, head of technical services at Alsons Aquaculture Corporation, which farms fish in the Philippines: I may have missed something, but I do not think the discussion is irritating.  In fact, I think it is rather interesting.  If Mr. Healey and his friends can be more specific in helping us shrimp farmers develop a technology from the interplay of field observations and the budding science that Mr. Van Wyk and Mr. Healey expound on, we will be on our way.

 

Adam Body: This is a list for discussing issues relating to shrimp farming.  As a farmer, I get a lot of value from the List.  I understand that some people want to put across a point of view that sometimes is colored by commercial considerations.  That’s fair enough in my opinion.

 

By the way, we use Kevin’s probiotics in our hatchery.

 

Mike Picchietti, president of a tilapia farm in Florida: The debate should not be about Kevin Healy’s product per se but about an aquaculturist’s ability to influence and manage the “competitive exclusion theory.”  Whose bugs may not be as important as our ability to manage/control microflora in our animals’ aquatic environment.  The aspects and techniques related to this are what is most enlightening and beneficial to this discussion.  Keep it coming.  Shrimp, tilapia, eel, or Dallas Weaver’s guppies.  Once you understand how to manage bugs, you’re going to win.

 

Dr. David Verner-Jeffreys, an aquaculture health specialist at the CEFAS Weymouth Laboratory in the United Kingdom: I agree that probiotics show promise, and I am also only too aware as a researcher that much of the published material is “sketchy” to say the least.  Those of us who have engaged in controlled studies have also noted that many of the products that are marketed do not even contain viable organisms.  As a reviewer, I also receive papers that are submitted for publication with highly dubious claims for probiotics, not backed up by good scientific evidence (you can imagine what generally happens to them).  Some of these studies probably resurface in the non-peer reviewed trade journals though.

 

I would strongly suggest that all shrimp farmers be extremely cautious before investing in unproven remedies.  As far as I am aware, no probiotic product has been authorized for use as either a veterinary medicine or a feed additive by a regulatory authority.

 

Michel Autrand, an aquaculture expert and shrimp farming consultant in France: Mr. Verner’s comments are very sensible.  Farmers should be very cautious about what is sold to them as innocuous and efficient.  Some of the bacteria used in probiotics are considered to be opportunistic pathogens, which is the case for Bacillus subtilis, one of the most frequently used species in probiotics.  If you search on the Internet, you will find several references to this problem.

 

David Bal: I have this contact in Taiwan—Ming—who is working at a company called Magellan Biotechnologies.  They are selling probiotics for shrimp and I am sure they could help you and provide data on this subject.  Contact Ming at mc.sun@msa.hinet.net.

 

Adam Body: We use Kevin’s probiotics in our hatchery.  Our hatchery is for our own farm: we do not sell the fry.  I am very keen to get the best possible quality fry.  I do not use antibiotics or any other type of chemical except chlorine and fertilizers for our algal culture.  My finding is quite clear: if we use the probiotics, plus molasses, we do not get luminescence.  My thoughts are that this means that the switch (or quorum sensing ability) of the Vibrios may be being disrupted by the additives.  We have tried molasses only and bugs only, but only the bugs plus molasses gave the results I wanted.  I will keep using the product because it gives me the results I want.

 

Herminio Simbol, production manager at the Aquamen shrimp farm in Madagascar and an aquaculture consultant: What’s our guarantee that the wonder bacteria of today won’t mutate into the monstrous nightmares of tomorrow?

 

Rod McNeil, a consultant on super-intensive shrimp culture systems and the developer of “AquaMats”®, artificial substrates for shrimp farms and hatcheries:

 

I’ll probably regret this, but here we go.  I work with AquaMats and have spent 6 years characterizing the microbial biota of finfish and shrimp culture in the presence and absence of structure (AquaMats).  What I can tell you is that the successional microbial growth on substrate is very different, depending on the nature of the system (ponds, tanks, raceways), and the presence or absence of structure dramatically affects the analytical water quality of the pond/tank.  Add to this that the species being reared and the nature of the feed also affects the order of succession in what finally becomes dominant.  All of these systems are extremely complex.  A typical biotic survey will identify some 25-50 algal species, over 100 fungi and 400 plus species of bacteria in a pond.  Unless you have a spare $250,000 for lab equipment and a few Ph.D.s wandering around the place with nothing to do, you’re probably not going to characterize the baseline microbial ecology of your ponds.  And, if you did, they would be completely different in a week.

 

In evaluating the use of probiotics in conjunction with and without structure, we have done a great deal of genetic mapping to look at dominant species and the effects of probiotics.  My conclusion, to date, after evaluating some 33 probiotics, is that some of them do nothing and some of them have a short-term effect that may last a couple of weeks.  Those that “work” (change the population distribution of the indigenous population) seem to reset the successional clock.  They essentially recreate a competitive environment characteristic of a point in time earlier in the “normal” succession.  Everything seems to affect that successional process.  Temperature, salinity, feed brands, stocking density, water exchange and light levels are a few that we’ve looked at.

 

Bottom line, I don't think there is much of a future in trying to control the microbial ecology of an aquaculture system until you fix all the variables (in my view close to an impossibility in open ponds) and then develop a probiotic based on that specific system.  In the meantime, those probiotics that are out there will be hit or miss.  Just because it works in one location doesn’t mean anything to its potential use in another locale.

 

Does resetting the successional clock have value?  Probably yes, if you happen to intercede at a point where a microbial pathogen (say a Vibrio) is becoming dominant.  The sudden introduction of a more nutritionally competitive species can knock down the concentration of Vibrios by 3 to 5 orders of magnitude for 4-10 days.

 

We have seen a strong correlation between the concentration of nitrogen (in all its forms, but the strongest correlation is with ammonia) in solution and the population of various Pseudomonads (Vibrio spp.).  With the wealth of information on biofiltration technology available today, I think you’re better off focusing on the water chemistry rather than the microbial ecology of the pond.  Lower nitrogen equals lower Vibrio.  Feed management is key to minimizing nitrogen nutrient loading.

 

This is not a sales pitch, just a measurable fact; AquaMats or any other form of structure (meaning surface area) can enhance the rate of nitrogen extraction and help reduce the likelihood that a pathogen can become sufficiently dominant to produce disease.

 

(Vasudevan: Our experience with AquaMats in Pulicat lake ponds showed no significant results in absorbing excess nutrients after 70 days of culture.  They did not prevent protozoan infections as claimed by Aquamat manufacturers.)

 

Kevin Healey: You are right to be concerned about the safety of the bacteria used as probiotics.  In relation to the safety of Bacillus subtilis, if you have a close look at the abstract you listed (relating to the bacterial whitespot syndrome), you won’t find any causative link between use of Bacillus subtilis and the so-called syndrome.  Please see the Aquatic Animal Pathogen and Quarantine Information System (AAPQIS), which clearly explains this (http://www.aapqis.org/main/path/viewpath.asp?PathID=3D57).

 

Bacillus subtilis is on the GRAS (generally regarded as safe) list of the United States Food and Drug Administration.

 

Todd Blacher (see page ??), former vice general manager of research and development at a super-intensive shrimp farm in China: Adam, in your hatchery, what kind of shrimp do you produce?  Vannamei, monodon, or other?  Can you tell us about your stocking densities, survival rates, probiotic dosages and molasses dosages?  I would also like to know your results prior to and post-use of probiotic/molasses additions.

 

Adam Body: We grow P. indicus.  We stock 80 to 100 naups per liter in our 20,000-liter tanks, which are filled to 15,000 liters when we stock.  We begin to apply “Platypus” (Kevin’s probiotic) as soon as we stock the naups at the rate of 25 milliliters of Platypus activated in 1,000 milliliters of seawater (refer to Kevin for details of the activation process).  We do this daily.  When ammonia begins to appear, we begin to apply molasses: 200 milliliters twice a day.  The tanks now have 18 to 20,000 liters of water.  Survival rates are usually better than 70%.  We harvest at PL-8.  Our results show that this procedure does the following:

 

1. Controls Ammonia

2. Stops Luminescence

3. Reduces Sludge

 

The important steps: use activated Platypus, use it daily, and use molasses as soon as ammonia presents.

 

S. Vasudevan: Algal blooms are always a big problem.  Some probiotics stabilize algae irrespective of salinity variations.  That is why we suggest farmers use both dyes and probiotics to get better results.

 

Durwood Dugger: a shrimp farming consultant in Florida, USA: Most of the work I have seen on pond dyes suggested they are far too expensive for commercial scale use and that was when the farmgate value of shrimp was two times what it is now—and of course you lose the dye with any water exchange.  (Vasudevan: Usually, the dye lasts for 2 months after application.)  Perhaps there are some extremely inexpensive new dyes available that I am not aware of.  Another potential problem with dyes or any kind of shading is that you may end up with pathogenic bacteria (probably Vibrios) in response to the high nitrogen levels that will be there after you shade out the algae that are currently using the nitrogen.

 

My readings on scientific comparisons of probiotics (there are literally hundreds of commercial products and very few with good scientific data showing reproducible performance) alone in ponds left me with the opinion that they are problematic at best—theoretically, clinically and economically.  Without complicated biochemical explanations, you have high algal blooms because your pond dynamics are such that they just favor algae, rather than bacteria.  That’s why you have an algal bloom in the first place rather than a bacterial bloom.  Adding a bacterial probiotic alone is not likely to change those dynamics sufficiently to displace the more efficient algal blooms (algae have the photosynthetic energy, metabolic advantage over bacteria), which will ultimately displace the bacterial probiotic because they are simply the best adapted to the conditions in your high nitrogen shrimp pond.  To change your pond dynamics you have to do something that will favor nonpathogenic bacterial domination.  In my experience you will need to provide a carbon source to displace the algae with a dominate heterotrophic bacterial population.

 

This past year we used animal grade molasses to repeatedly shift (at will) lined ponds from algae-dominated blooms to bacteria-dominated blooms.  We added a half kilo of molasses for every kilo of feed.  Usually, the bacterial bloom would displace the algal bloom in less than a week.

 

We also monitored the algal displacement by measuring the diurnal oxygen (photosynthetic) swings in the ponds, which stabilized as the bacterial blooms developed.  We used no probiotics; the required bacteria were always there—naturally available when the dynamics were right for them to bloom.

 

 

Participants

(In Alphabetical Order)

 

Eluri Apuchand, Vintech, Buddhavaram-Post, Gannvaram-Mandal, Krishna District, Andhra Pradesh, India 521 101 (phone/fax 91-8676-256315, email apuchand@yahoo.com, website under development).

 

Michel Autrand, 127 Av. Peyre Grosse, 34980 Saint Clement de Riviere, France (phone/fax 33-4-676-70012, email michel.autrand@wanadoo.fr).

 

David Bal, 17 rue de la Tournette, 74150 Rumilly, France (phone 0660765235, email ichtyos@yahoo.fr, webpage http://perso.wanadoo.fr/david.bal).

 

Todd Blacher (toddblacher1@yahoo.com).

 

Phil Boeing, 53300 Avenida Navarro, La Quinta, CA 92253 USA (phone 760-564-1421, cell 760-899-6082, email pboeing@dc.rr.com).

 

Adam Body, P.O. Box 39346, Winnellie, NT, 0821 Australia (phone 08-89886861, fax 08-89886859, email a.body@bigpond.com).

 

Durwood Dugger, BioCepts International, Inc., 947 Sandpiper Lane, Vero Beach FL 32963 USA (phone 772-332-1046, fax 772-234-8966, email duggerdm@bellsouth.net, webpage http://www.biocepts.com).

 

Daniel F. Fegan, Alltech Biotechnology Corp, Ltd., 5th Floor, Preecha Building, 2533 Sukhumvit Road, Bangchack, Prakhanong, Bangkok 1260 Thailand (phone 66-2742-4545, fax 66-2742-4547, email dfegan@alltech.com).

 

Kevin Healey, International Animal Health Products, 18 Healey Circuit, Huntingwood NSW 2148, Australia (phone 61-2-9672-7944, fax 61-2-9672-7988, email khealey@iahp.com.au, webpage www.iahp.com.au).

 

Antonin Jamois, Les Gambas de l’Ankaranana, 2 rue Lavigerie BP 212, Diego-Suarez, Madagascar (email antosiomaj@yahoo.fr, webpage http://www.madagascar-gambas.com).

 

Pablo Legarda (sffarming@yahoo.com).

 

Ramon Macaraig, Alsons Aquaculture Corporation, 2286 Pasong Tamo Extension, Makati City, Metro Manila, Philippines (phone 63-83-508-2300, fax 63-83-508-2304, email monmac52@yahoo.com).

 

Roderick McNeil, Meridian Aquatic Technology, LLC, 303 Kerr Dam Road, P.O. Box 876, Polson, MT USA 59860 (phone 406-883-6921, fax 406-883-8592, email mcneilrj@digisys.net, webpage www.aquamats.com).

 

Claudio Paredes, Agribrands Purina Venezuela, Av. Principal de Los Ruices, Edif. Stemo, Piso 6, Los Ruices, Caracas, Venezuela (phone 58-212-2399111, fax 58-212-2352002, email claudiop@agribrands.com, webpage www.agribrands.com).

 

Mike Picchietti, Regal Springs Tilapia, P.O. Box 20608, Bradenton, FL 34204 USA (phone 941-747-9161, fax 941-747-9476, email picchietti@aol.com, webpage http://www.regalsprings.com).

 

Juan Carlos Quintana, Maricultura del Pacifico, S.A. de C.V., Pesqueira 502, Local 6, Mazatlán, Sinaloa 82040, México (phone 52-669-985-1506, email jcquintana@maricultura.com.mx).

 

Bob Rosenberry, Shrimp News International, 10845 Scripps Ranch Boulevard, #4 San Diego, CA 92131 USA (phone 858-271-6354, fax 858-271-0324, email bob@shrimpnews.com, webpage http://www.shrimpnews.com).

 

Herminio B. Simbol, Aquamen, EF Tsangajoly, Morondava, Madagascar (phone 873-761-608-146); and Aquaculture Asia Consultants Corp., 2146 San Roque 2, San Jose Occidental, Mindoro, Philippines (phone 6343-491-2311, email herminiobsimbol@yahoo.com).

 

Paul Smith, Ph.D., University of Western Sydney, School of Science, Food and Horticulture, Building 21, Room 100, Campbelltown, New South Wales, Australia (phone 61-7-3329-1629, fax 61-7-3025-1621, email pt.smith@uws.edu.au, webpage http://www.uws.edu.au/sfh).

 

B. Suryakumar, Hitide Seafarms, 26 Mariyannapalya Bangalore 560024, India (phone 001-80-23430617, fax 001-80 51123000, email hitide@vsnl.com).

 

Leonido C. Tala, AQUAMEN EF (Aquaculture du Menabe-Enterprise Franche), BP 323, Morondava 619, Madagascar (phone 873-761-608146, fax 873-761-608148, email leonidoctala@yahoo.com).

 

Peter Van Wyk, Southwest Virginia Aquaculture Research Center, 424 West Main Street, Saltville, VA 24370 USA (phone 276-496-4999, fax 276-496-4974, email pmvanwyk@msn.com, webpage http://arecs.vaes.vt.edu/arec.cfm?webname=saltville).

 

S. Vasudevan: Dr. S. Vasudevan, Hi-Line Aqua, 28/1, Soundaram Apartments, Third Main Road, Kasturba Nagar, Adyar, Chennai - 600 020 India (phone 91-44-24416311, fax 91-44-24420591, email vasu@xlweb.com, webpage http://www.hi-lineaqua.com).

 

Sunil Kant Verma, FH-15, Haldi Colony, P.O. Haldi, Pantnagar-263145 (Uttranchal), India (phone 05944-230342, email  skv_fish@rediffmail.com).

 

Dr. David Verner-Jeffreys, CEFAS Weymouth Laboratory, The Nothe, Weymouth, Dorset, DT4 8UB United Kingdom (phone 44-1305-206725, fax 44-1305-206001, email d.verner-jeffreys@cefas.co.uk, webpage http://www.cefas.co.uk/homepage.htm).

 

G. Vijayaraghavan (vijayaraghavang@yahoo.com).

 

Dallas E. Weaver, Ph.D., Scientific Hatcheries, 5542 Engineer Drive, Huntington Beach, CA 92649 USA (phone 714-890-0138, fax 714-890-3778, email deweaver@surfcity.net, webpage http://www.scientifichatcheries.com).

 

Anthony Xavier (tony2xl@yahoo.co.in).

 

The Shrimp List: The Shrimp List.  Subject: This discussion took place under more than a dozen different topics, mostly during late October 2004.

 

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