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Antibiotics and Shrimp Farming

Shrimp News (bob@shrimpnews.com): This is one of the longest discussion that has ever taken place on The Shrimp List, and it often strays away from shrimp farming.  To keep it at a manageable length, I excluded most of the comments that did not relate directly to shrimp farming—or that were difficult to understand.  To read the full discussion, go to The Shrimp List’s webpage.

Juan Aguirre (jxaquirre58@yahoo.com): What do the members of the Shrimp List think about the use of antibiotics in shrimp farming?

Durwood Dugger (ddugger@biocepts.com): Juan, I suspect that a significant number of the shrimp that test positive for antibiotics are false positives, caused by background levels of antibiotics and related chemicals.

Nelson Gerundo (nelsongerundo@yahoo.com): Juan, antibiotic residues in food animals are a global problem.  They are regulated to safeguard humans from eating meat, poultry, eggs and milk containing either banned antibiotics or antibiotics with residue levels above legal amounts.

The reason antibiotics tarnish the reputation of farmed shrimp in Asia is that there are some shrimp farmers here who are still using them.  As detection methods become more sensitive, antibiotics are found more frequently.  Fortunately, most shrimp farmers in Asia do not use antibiotics.

Patrick Wood (patrickjwood@yahoo.com): The shrimp feed manufacturers are more responsible for antibiotic residues in exported shrimp than the shrimp farmers.  I’ve seen this in India.  Unscrupulous feed companies market feeds with antibiotics, and the word spreads that those feeds are the best feeds.  Farmers don’t care because they sell to processors who consolidate their shrimp with the shrimp from other farmers.  Antibiotic testing of shrimp is slow and expensive for the processor, especially when dealing with harvests from many small farms.

Regulations and traceability back to the farm would help.  Then, the processor could go back after the fact and pressure farmers to stop using antibiotics, or stop doing business with them.  A black list would be good idea, especially if it went all the way back to the feed manufacturers.  In the case of India, regulators (like the Marine Products Export Development Authority, MPEDA) could revoke the licenses of feed companies.  Organizations that certify feed companies (like the Global Aquaculture Alliance, GAA) help, but they are expensive for small-scale farmers and hard to implement in places where even a BRC Global Standards certificate can be bought for $535.

Interestingly, value-added shrimp, which undergo more handling and washing, seem to have lower antibiotic levels than whole shrimp, which indicates that the heads and shells have greater concentrations of antibiotics than the tails.

A concerted effort is needed to correct the antibiotic problem in shrimp farming.  Otherwise all of us will have to face bad reputations and loss of market share.  In India bamboozling is an accepted practice.

Greg Lutz (glutz@agcenter.lsu.edu, editor of Aquaculture Magazine): Patrick, would you be interested in writing an article about the use of antibiotics in shrimp farming for Aquaculture Magazine?  Does anyone else have a good idea for a story?

Nelson Gerundo (nelsongerundo@yahoo.com): Go for it Patrick.  Start writing about it.  You’ve witnessed antibiotic use around the world.

Juan Aguirre (jxaquirre58@yahoo.com): Patrick has a lot of experience, but there are many others on this list who have also worked in many countries, and their input would be appreciated on this and other shrimp farming topics.

Greg Lutz (glutz@agcenter.lsu.edu): Questions are welcome, too!  I could imagine an entire article some day of questions the shrimp farming industry will face in the near future and out several decades.  No answers.  Just questions.  That might start a proactive process.

Ram Raj (padlab@yahoo.com): Patrick, you have leveled unsubstantiated and wild allegations against shrimp feed manufacturers in India.

Regulatory agencies like the Coastal Aquaculture Authority (CAA) and the Marine Products Export Development Authority (MPEDA) take periodic samples to screen for antibiotics in India.  Why would feed manufacturers take the risk of intentionally adding antibiotics, knowing that they are checked and that they do not help to mitigate the disease?

Patrick Wood (patrickjwood@yahoo.com): Ram, I would be very interested in understanding how you think detectable levels of antibiotics get into shrimp in India, resulting in rejections by the USA and EU and how/why they have spiked in the last year?

Do you think processors/exporters are adding antibiotics as a processing aid or additive?

Even MPEDA is concerned.  It can’t be held accountable for all the issues in India.  There are illegal shrimp farms in India now.  There are cowboys there gaming the system.  Just read your local news and also look at international websites like SeafoodSource and Intrafish.  Global Aquaculture Alliance (GAA) certified exporters have even been caught with antibiotics in their exports out of India—yes caught!

This is about proven and detectable levels of antibiotics in exported Indian shrimp, not about whether antibiotics work or not on diseases in shrimp aquaculture, nor is it about high levels of antibiotics from the water or the air.  These are not wild allegations.  Of course, there are many reputable feed manufacturers in India, but there are also cowboys.  From buying shrimp globally over past twenty years, I can say that India has had one of the highest rates for rejected shipments.

I have many Indian friends in the business who are serious players and who understand that there are also cowboys in India—not just Indians.

Patrick Wood (patrickjwood@yahoo.com): I have a feeling that many shrimp farmers don’t post to The Shrimp List because they may get their wrists slapped, or get fired, or cannot comment on their employer’s policies/strategies.  That’s a shame.  It would be much more interesting if they came forward.

Ram Raj (padlab@yahoo.com): Patrick, you are skirting away from the false allegations you have leveled against the feed manufacturers in India.

Periodic list of residue detections in EU and the USA are very much available in the public domain.  India and several other countries have had problems.  If you analyze the figures from 2009 till now and compare them with the shrimp produced and exported from India, which grew from 8,000 metric tons in 2009 to over 400,000 tons (head-on, ex-farm figures) in 2015, you would discover the fact that rejections are coming down proportionately and that the efforts to control antibiotic residues are working.

Greg Lutz (glutz@agcenter.lsu.edu): I agree: Ram does not have a defensible position—just bluster in the hope of silencing those who cite facts.

Ram Raj (padlab@yahoo.com): Greg, would you or Patrick please give me your facts on the antibiotics used by the Indian Feed Companies?  If you have reservations about posting to The List, you could send them to my personal email.

Patrick Wood (patrickjwood@yahoo.com): Ram, it will benefit shrimp farmers globally if they all stop using prohibited antibiotics.  I question though how you now seem to be insinuating that because of India’s growth in Penaeus vannamei farming that India should be given leeway in controlling residues.  It’s zero tolerance.  No one is moving the goal posts for India and bending the rules is not going to happen.

It is very clear that India should bring antibiotics under control and look at the long-term, not the short-term gains.  Otherwise you are just tainting all of us in the industry.

The job starts with the feed industry in India.  You cannot get round it.  The proof is in the pudding...or in this case the shrimp.

For importers and distributors, the fear of a recall after the product hits the retail market is frightening.  It’s not just about testing on the border, but agencies reserve the right to test in retail markets as well.  This happens and has almost put some companies out of business.  It certainly has made them wary of buying from certain countries and companies.

Nelson Gerundo (nelsongerundo@yahoo.com): Ram, there is an article in the Indian Journal of Geo-Marine Science written by Swapna et al. (2012) on the incidence of antibiotic residues in farmed shrimp from the southern states of India.  In the article, Swapna, Rajesh and Lakshmanan say: “It has been noticed antibiotics are usually administered in aquatic feeds and most commercial shrimp feeds contain antibiotics,” citing Flahery et al. (2000, Conclusion, 3rd Sentence, Page 347).

Following their citation, Flaherty et al. 2000, say: “One of the most common and worrisome pond additives is antibiotics.  Most commercial shrimp feeds are enriched with common antibiotics such as oxytetracycline.”

Ram Raj (padlab@yahoo.com): Patrick, I’m not in denial that India has had an antibiotic residue issue in its farmed shrimp, and we aren’t looking for a pass on this issue as you have wrongly presumed.  Zero tolerance applies to India and all other countries.  There is no second opinion on the fact that we have to address the issue, and we are addressing it.

The source of antibiotic residue in farmed shrimp could be from anything that goes into the farm, from postlarvae (PLs) to feed to the various inputs that go into a pond.  Feed is a major input of course, and in India, there are verifiable checks for antibiotic residues.  I believe that the best way to address the issue would be to identify the source of the antibiotics and work to eliminate them.

Daniel Gruenberg (seagardenfoods@mac.com): Ram, antibiotics from PLs?  Seriously?  A typical PL weighs 0.01 gram and harvest shrimp about 20 grams.  So, not only do you have a 2,000-fold increase in weight to deal with, but you also have a 90-day withdrawal period.  Sorry, but I can categorically say PLs are not the source of your residue problem.

Ram Raj (padlab@yahoo.com): Daniel, nitrofuran metabolites and chloramphenicol residues can remain in the tissue for long periods.  These antibiotics when used at parts-per-million levels in larval tanks may probably be detected at parts-per-billion levels at the time of harvest.  A 3-log increase in body weight will have a corresponding 3-log reduction in tissue residue concentration.

Daniel Gruenberg (seagardenfoods@mac.com): You are of course correct if you only look at the dilution by growth, but there is also the diminishing of the antibiotic during a 90-day growout period.  It’s absolutely crazy to be using banned antibiotics with carcinogenic metabolites in PLs.  It should be a simple academic process to test the various possible sources and to police the use of banned antibiotics.

I don’t have the pharmacokinetics data in hand for PLs, but I have read papers that hatcheries get higher survival during transport when using antibiotics.  I would say this is just laziness on the hatchery’s part, perhaps with a dash of incompetence.  My hatchery uses zero antibiotics, and we get near 100% survival, even with 36-hour air shipments.

Thailand has invested in a strong antibiotic surveillance program since around 2000, and it shows!  Thailand has one of the lowest rejection rates of any major shrimp producer in Asia.  I’m not saying this to brag.  I’m saying it as an example of the hard work that’s required to deal with this problem and that it can be done!

Good luck, and I hope India can manage this problem.  In my opinion, any country’s problem with antibiotic residues is a problem for the whole industry because it reflects poorly on farmed shrimp in general.

Arul Victor Surish (avictor.suresh@gmail.com): I manage feed formulation and related technical matters for Growel Feeds, a shrimp feed company in India.  We do not add any antibiotics to our feeds.  Additionally, we routinely monitor the nutrient profile of four of our competitors’ products, and we include antibiotics in the analysis.  Together, all five companies represent about 80-85% of the Indian shrimp feed market.  We have not found any incidence of antibiotics in any of the feeds in the last three years.  Saying that Indian feed manufacturers add antibiotics to the feeds is unsubstantiated.  Ram is correct on this issue!

Nelson, I went through your Swapna et al. (2012) reference.  As you pointed out, Swapna et al. conducted their analysis on the shrimp, not the feeds.  As far as your question on their statement—“Antibiotics are usually administered in feeds and most commercial shrimp feeds contain antibiotics”—please note that it is not the author’s finding, but a statement attributed to another citation which is not specific to India.

Krishna Murthy (murthy_hyr60@yahoo.co.in): Dear List, sometimes the source of antibiotics can be from sources other than actual antibiotic usage in the water or the feed.  In fact, three containers of shrimp (about 55 tons) from a leading, integrated shrimp project in the world that I worked for in the mid 2000s were rejected by Japan because of antibiotics.  The shrimp farm never used any antibiotics in the hatchery or growout ponds, nor in the feed that it produced at its own feed mill, but the shipment was positive for antibiotics.  When the farm investigated the problem, it proved that the source of the antibiotic residues was from the poultry manure (poultry droppings in pellet form) that it used for fertilizing the ponds.  The farm immediately stopped using poultry manure.

Blaming the feed mills is not always correct, and we should continue to look for other sources.

Daniel Gruenberg (seagardenfoods@mac.com): This is another reason why I never ever use manure in shrimp ponds.

Nelson Gerundo (nelsongerundo@yahoo.com): Krishna, Even the poultry feather meal sometimes incorporated in aquaculture feed could be a source of antibiotics residue in shrimp.

Jim Wyban (jim.wyban@gmail.com): Dear Shrimp List, here’s some recent news on shrimp antibiotic rejections.

The U.S. Food and Drug Administration (FDA) refused a total of 142 entry lines* of imported seafood in October 2016, of which only one (0.7 percent) was from banned antibiotics in shrimp, the lowest number since 2013.

[*Shrimp News: FDA refusals ‎are not of shipments; rather they are defined as “entry lines.”  A single container of shrimp shipped to the United States could include multiple entry lines.  For example, a single container of imported shrimp could contain peeled and deveined shrimp (PND) of multiple count sizes.  An importer can break this shipment out into multiple entry lines—PND/31-40/count as one, PND/41-50/count as another and PND/51-60/count as a third.  If all of this shrimp is contaminated with antibiotics and detected by the FDA, then that single container load would be reported as three entry line refusals.

An entry line is a product in a container.  Example: A container of imported shrimp (40,000 pounds) may have several different types of shrimp within that container such as peeled and deveined, cooked, breaded and headless shell-on.  Each different type of product in that container has its own code and each product is considered an ‘entry line’”.]

So far in 2016, FDA has refused a total of 113 entry lines of shrimp products for reasons related to banned antibiotics, compared to a total of 377 entry lines of shrimp products rejected through the first nine months of 2015.

The entry line refusal into the USA in October due to antibiotics contamination was shipped by Frozen Seafoods Factory No. 32, a Vietnamese company.

Despite the small number of refusals for shrimp contaminated with banned antibiotics by the FDA, the Southern Shrimp Alliance (SSA) stresses that that does not indicate that the use of antibiotics has been eliminated from shrimp farms by certain exporting countries.  For example, the Canadian Food Inspection Agency (CFIA) reported that in October a shrimp shipment was rejected from Vietnam’s Huy Nam Seafoods Co., Ltd., for fluoroquinolones.  And CFIA announced that the Chinese firm Shunde Bangmin Aquaculture Farms has been added to its Mandatory Inspection List for fluoroquinolones along with Indian shrimp exporter Falcon Marine Exports, Ltd., for nitrofurans.

In addition, SSA revealed that of the 61 total shipments refused entry into Japan in October 2016 by the Ministry of Health, Labor and Welfare because of violations of the Food Sanitation Law, seven (11.5 per cent) were for shipments of shrimp products contaminated with banned antibiotics.  Six of these shipments originated in Vietnam and one originated in India.

The seven rejected shipments by Japan belonged to the following firms:

  1. Thuan Phuoc Seafoods and Trading Corporation (Vietnam): frozen broken sushi ebi vannamei (detection of furazolidone).
  2. Ngo Bros Seaproducts Import-Export One Member Company Limited (Vietnam): frozen nobashi vannamei shrimp (detection of furazolidone).
  3. Minh Phu Hau Giang Seafood Corp. (Vietnam): frozen vannamei PTO coated by potato starch shrimp (detection of sulfadiazine).
  4. Cuulong Seaproducts Company (Vietnam): frozen PD vannamei shrimp (detection of furazolidone).
  5. Thong Thuan Company Limited (Vietnam): frozen sushi shrimp (boiled, peeled shrimp, detection of sulfadiazine).
  6. Trong Nhan Seafood Co., Ltd., (Vietnam): frozen IQF cooked and peeled vannamei shrimp (detection of enrofloxacin).
  7. Asvini Fisheries Private Limited (India): frozen HLSO vannamei shrimp (detection of furazolidone).

Dallas Weaver (deweaver@me.com): The insanity of the regulatory bureaucrats becomes clear with the words “zero tolerance.”  Because of ambient levels of almost all antibiotics and our ability to measure them at parts-per-billion levels, it is insane to set residual tolerance standards at zero.  As analytical chemistry continues to evolve to parts per trillion, literally one atom in a sample (like what we can already do with radioisotopes), the tolerance level will have to be defined well above “zero.”

John Birkett (jbirkett42@yahoo.com): Dallas, what I find difficult to understand is the zero tolerance for antibiotics in shrimp and the fact that the poultry industry can use fourth generation antibiotics and nobody even checks for residuals.

Daniel Gruenberg (seagardenfoods@mac.com): I’m allergic to cephalosporins and penicillins, and I once went into anaphylactic shock after eating a McChicken sandwich in Tokyo.  Lucky my host was a doctor and gave me epinephrine in time to save me.

So antibiotic residuals are something I feel very strongly about because my own life depends on avoiding them.  That being said, “zero tolerance” laws are insane as Dallas says.  I can think of no better word to describe them.

Why governments can spend trillions of dollars on foreign wars and billions on climate change computer simulations, but can’t run a simple safety test on antibiotics is beyond reason.  Farmers must minimize the use of antibiotics for no other reason than protecting themselves against future resistance.

Antibiotics affect ecosystems in unpredictable ways.  The less we use them, the better our ecosystems will work and the better they will work for us when we truly need them.

Dallas Weaver (deweaver@me.com): Note that some of these organic chemicals are of emerging concerns with highly treated human wastewaters.  Modern sewage treatment, with huge co-metabolism capacity for trace organics, and full tertiary treatment for water reuse still has some of these chemicals coming through the system at parts-per-billion and lower levels.

If you use a water supply that had a contribution from treated sewerage water (any lower salinity shrimp pond in today’s crowded world), you can have very low, but not zero levels that are presently below measurement levels, but won’t be in the future.  Antipsychotic drugs, antibiotics, antifungals and hormones of many kinds are found in sewage and get through most treatment systems.

  Nelson Gerundo submitted the following information to The Shrimp List on the prohibited antibiotics in several countries around the world.  

Nelson Gerundo (nelsongerundo@yahoo.com): India’s MPEDA Quality Control Laboratories has an established residue monitoring program, not only for antibiotic residues but also for other unauthorized substances like hormones, pesticides, heavy metals, mycotoxins, carcinogenic antimicrobial dyes and the antioxidant ethoxyquin.

MPEDA is further intensifying its campaign to stop the use of illegal antibiotics by shrimp farmers in response to the EU crackdown on shrimp imports from India.

Shrimp with antibiotics continue to taint the reputations of the countries that use them and the reputations of all shrimp farmers in Southeast Asia.

United States: The USA Food and Drug Administration (FDA) considers the following antibiotics as prohibited for extra-label use with no residue permitted (zero tolerance) in shrimp:

1. Chloramphenicol.

2. Nitrofurans (furazolidone, nifurpirinol, nitrofurazone, nitrofurantoin, nifuraldezone, furaltadone).

3. Quinolones (nalidixic acid, oxolinic acid, pipemidic acid).

4. Fluorinated Quinolones:
      a. 1st generation (nalidixic acid, oxolinic acid, pipemidic acid).
      b. 2nd generation (ciprofloxacin, norfloxacin, ofloxacin).
      c. 3rd generation (levofloxacin, temafloxacin, grepafloxacin).
      d. 4th generation (gemifloxacin, moxifloxacin, gatifloxacin) and exclusive veterinary
e. preparations (enrofloxacin, marbofloxacin).

5. Nitroimidazoles (metronidazole, dimetridazole, ipronidazole, tinidazole,
ronidazole, azanidazole).

6. Non Steroidal Stilbestrol (diethylstilbestrol).

7. Steroids (estradiol, progesterone, hydrocortisone).

8. Antimicrobial Dyes (malachite green, gentian violet).

9. Beta Adrenergic Agonists (clenbuterol, bambuterol, salmeterol, indacaterol).

10. Glycopeptides (vancomycin, televancin, bleomycin, ramoplanin).

 

European Union: The residue substances in imported fish and crustacean that are of greatest concern to the European Union based on the Council Directive 96/23/EC are as follows:

1. Stilbenes (diethylstilbestrol, hexestrol, dienestrol).

2. Steroids (methyltestosterone, estradiol, stanazolol, progesterone, flugestone).

3. Chloramphenicol.

4. Nitrofurans (furalozidone, furaltadone, nitrofurazone, nitrofurantoin).

5. Nitroimidazoles (metronidazole, dimetridazole, ipronidazole, tinidazole, ronidazole,
azanidazole).

6. Antibacterial Substances
      a. Beta-Lactams (benzylpenicillin, ampicillin, cephalexin, meropenem, nacordicin).
      b. Tetracyclines (oxytetracycline, chlortetracycline, methacycline, doxycycline).
      c. Sulfonamides (sulfadiazine, sulfamethoxazole, sulfaguanidine).
      d. fluoroquinolones.
            (a) 2nd generation (ciprofloxacin, norfloxacin, ofloxacin).
            (b) 3rd generation (levofloxacin, temafloxacin, grepafloxacin).
            (c) 4th generation (gemifloxacin, moxifloxacin, gatifloxacin).
            (d) exclusive veterinary preparations (enrofloxacin, marbofloxacin).
            (e) aminoglycosides (kanamycin, amikacin, neomycin).
            (f) Macrolides (erythromycin, clarithromycin, azithromycin, oleandomycin).

7. Anthelmintics (ivermectin, thiabendazole, albendazole, levamisole).

8. Dyes (malachite green, gentian violet).

9. Mycotoxins (aflatoxin, ochratoxin, trichothecenes, fumonisins).

10. Organochlorine Compounds (chlordane, heptachlor, lindane, toxaphene, DDT).

11. Growth Enhancing Feed Additives (olaquindox, carbadox, quindoxin).

 

Japan has a zero residue tolerance in shrimp for the following Agricultural Chemicals, Antiparasitic, Antipsychotic and Antimicrobial Drugs:

1. Herbicides (2,4,5-trichlorophenoxyacetic acid, propham).

2. Fungicide (captafol).

3. Growth Promoting Additives (carbadox, olaquindox).

4. Antibiotics
      a. Chloramphenicol.
      b. Nitrofurans (furazolidone, furaltadone, nitrofurazone, nitrofurantoin).

5. Antipsychotic (chlorpromazine).

6. Anti-Trematodal (clorsulon).

7. Insecticide (coumaphos).

8. Plant Growth Regulator (daminozide).

9. Stilbene (diethylstilbestrol).

10. Nitroimidazoles (metronidazole, dimetridazole, ipronidazole, tinidazole, ronidazole,
azanidazole).

11. Antimicrobial Dye (malachite green).

Previously, the Maximum Residue Limit (MRL) for ethoxyquin residue shrimp in Japan was 0.01 ppm.  Now it’s 0.2 ppm.  Click here for Japan’s MRLs for shrimp.

Canada has a “zero residue tolerance” in shrimp for the following veterinary drugs as imposed and monitored by the Canadian Food Inspection Agency:

1. Stilbenes (diethylstilbestrol, hexestrol, dienestrol).

2. Anabolic Steroids (boldenone, methyltestosterone, nandrolone).

3. Antimicrobial Substances.
      a. Amphenicols (chloramphenicol, thiamphenicol).
      b. Nitrofurans (furazolidone, furaltadone, nitrofurazone, nitrofurantoin).
      c. Nitroimidazoles (metronidazole, dimetridazole, ipronidazole, tinidazole, ronidazole,
azanidazole).
      d. Tetracyclines (tetracycline, chlortetracycline, methacycline, doxycycline).
      e. Sulfonamides (sulfacetamide, sulfamerazine, sulfamethazine, sulfamethoxazole,
sulfaguanidine).
      f. Quinolones (flumequin, nalidixic acid, oxolinic acid, pipemidic acid).
      g. Fluoroquinolones.
            (a) 2nd generation (ciprofloxacin, norfloxacin, ofloxacin).
            (b) 3rd generation (levofloxacin, temafloxacin, grepafloxacin).
            (c) 4th generation (gemifloxacin, moxifloxacin, gatifloxacin).
            Exclusive Veterinary Preparations (enrofloxacin, marbofloxacin, danofloxacin).
      h. Antimicrobial Dyes (malachite green, gentian violet).

4. Macrocyclic Lactones (ivermectin, doramectin, moxidectin, eprinomectin).

Click here for Canada’s MRLs for veterinary drugs.

China has a zero residue tolerance for the following veterinary drugs in shrimp, as imposed by China’s Ministry of Agriculture.

1. Stilbenes (diethylstilbestrol, hexestrol, dienestrol).

2. Anabolic Steroids (zeranol, trenbolone, megestrol, boldenone, methyltestosterone
nandrolone, estradiol propionate).

3. Antimicrobial Substances.
      a. Chloramphenicol.
      b. Nitrofurans (furazolidone, furaltadone, nitrofurazone, nitrofurantoin).
      c. Nitroimidazoles (metronidazole, dimetridazole, ipronidazole, tinidazole, ronidazole,
azanidazole).
      d. Antimicrobial Dye (malachite green).
      e. Anti-Leprosy (dapsone).

4. Psychotropic Drugs (chlorpromazine, phenobarbital, promethazine, amobarbital,
reserpine, methaqualone, diazepam).

5. Molluscicide (pentachlorophenol sodium).

6. Stimulants (clenbuterol, salbutamol, cimaterol).

7. Growth Promoters (sodium nitrophenolate, nitrovin).

8. Beta Adrenergic Agonists (clenbuterol, bambuterol, brombuterol, clorprenaline
salbutamol, ractopamine, cimaterol, terbutaline).

9. Sympathomimetic Amine Agonist (Dopamine HCL).

Sources: 1. The Shrimp List (a mailing list for shrimp farmers).  Subjects: (1) Antibiotics (2) Antibiotics and Input from Others on The List.  November 1 to 14, 2016.  2. Bob Rosenberry, Shrimp News International, November 16, 2016.

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