20 Agricultural Research/January 2004

robiotics are live, nonpathogen-ic bacteria that contribute to thehealth and balance of the intesti-nal tract. They are given orallyto poultry to help the birds fight

illness and disease. Prebiotics are non-digestible foods or nutrients that probi-otics need to stimulate metabolism. Theyfeed the beneficial bacteria and modifythe composition of intestinal microfloraso probiotics can predominate.

Annie Donoghue is a poultry physi-ologist and research leader at the ARSPoultry Production and Product SafetyResearch Unit in Fayetteville, Arkansas.She’s part of a team of researchers find-ing new healthful bacteria to feed poul-try and beat back harmful pathogenswhile also making the poultry grow moreefficiently.

Donoghue is leading and coordinat-ing the research team in several areas ofprobiotic research. Her husband, DanDonoghue, is heading the Campylo-bacter work at the Department of Poul-try Science at the University of Arkansas.Billy Hargis is leading the Salmonellawork there. Guillermo Tellez, a visiting

professor from the College of VeterinaryMedicine at National Autonomous Uni-versity of Mexico in Mexico City, wasrecently appointed as a researcher withthe University of Arkansas and is explor-ing the interactions between the gut andbacteria. The team also includes severalgraduate students from both the UnitedStates and Mexico who have been inte-gral team members on this project.

Pathogens such as Salmonella andCampylobacter are the main causes offoodborne illness from poultry consump-tion. The research team wants to reducemicrobial populations typically found inlive poultry before they’re processed forfood. They’re trying to get a better un-derstanding of how probiotics influencethe microbial environment of the gut andhow they interact with other bacteria.

On the Market and in the PipelineOne of the ways they are attempting

to do this is identify good bacteria (pro-biotics), test their ability to outcompetethe bad bacteria in the laboratory, andthen use them to protect poultry.

The concept of the good bacteria out-competing the bad is known as competi-tive exclusion and has been around formany years. Bacteria are fed to newlyhatched poults and these bacteria occupysites in the intestinal tract that would beoptimal for pathogen attachment and col-onization. Since the nonpathogenicbacteria get to the intestinal sites first andare able to colonize the gut, they reducethe opportunity for pathogenic bacteriato establish in newly hatched poults whenthey are most susceptible to infection.

In fact, ARS scientists have been onthe forefront of this research. The Foodand Feed Safety Research Unit inCollege Station, Texas, developedPREEMPT, a blend of 29 organisms thatcan be sprayed over newly hatchedchicks to keep Salmonella from settlingin their intestines. It was licensed by FDA(U.S. Food and Drug Administration)and manufactured commercially as aprophylactic. And ARS scientists at the

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Probiotics Protect PoultryFrom Pathogens

Candidate good bacteria outcompetepathogens in the laboratory. Here,physiologist Annie Donoghue gives acombination of these bacteria to a turkeypoult to test their efficacy in the live bird.

STEPHEN AUSMUS (K10911-1)

Poultry Microbiological Research Unitin Athens, Georgia, developed theMucosal Starter Culture to prevent thegrowth of Salmonella and Campylo-bacter in newborn chicks. It is awaitingFDA approval.

The Fayetteville team consisting ofARS and University of Arkansas re-searchers have added a new dimensionto this process by testing the ability ofpotential probiotic bacteria to outcom-pete the pathogens in vitro. Previouscultures have been less stringentlyscreened. Commercial producers indeveloping countries had some success,but questions arose because somecultures were undefined (meaning not allthe bacteria have been identified) andthere is a fear in the United States andEurope that they could contain emergingpathogens.

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Understanding how probiotics influencedevelopment and health of a young turkey’sgastrointestinal system is a majorcomponent of ARS collaborative researchwith Mexican scientists. Visiting scientistMemo Tellez (seated) and Mexicangraduate students currently studying at theUniversity of Arkansas work with AnnieDonoghue (behind Tellez) to evaluate howthese bacteria enhance the enteric function.Standing left to right are Alberto Torres,Gerardo Nava, and Vicente Salvador.

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21Agricultural Research/January 2004

ARS’s Reach Is Worldwide

Collaborations such as the Poultry Production and ProductSafety Research Unit’s partnership with the University ofArkansas and Mexican scientists to gain new insights into useof beneficial bacteria in poultry wouldn’t be possible withoutsupport from the ARS Office of International ResearchPrograms (OIRP).

Many ARS research projects are designed to tackle prob-lems that have impacts felt around the world. OIRP helps ARSresearchers conduct research in nations where mutual inter-ests exist in areas including animal health, biotechnology andbiosafety, protection of crop health and pest control, food safe-ty, and water and environmental conservation.

With guidance from OIRP, ARS researchers throughout theUnited States and overseas are collaborating with scientistsfrom several nations, including Brazil, Israel, and countriesof the former Soviet Union. Besides investigating food safe-ty, Mexican counterparts are collaborating on several projects.

For example, ARS researchers in Kerrville, Texas, are working with scientistsfrom Mexico’s National Research Institute of Forestry and Agriculture (INIFAP)in Cuernavaca, Morelos, to determine the nature and scope of resistance insouthern cattle ticks and horn flies to pyrethroid and organophosphate pesticides.Their work includes developing practical guidelines to manage this resistanceand protect livestock. They hope to create assays to monitor such resistance.

In another joint project, Mexican scientists in the Toluca Valley are screen-ing potato genotypes that ARS scientists are developing for resistance to lateblight (Phytopthora infestans), the most important potato disease worldwide.Since all known strains of late blight have occurred in the Toluca Valley, thiscooperation is imperative if new varieties are to resist potential future strains.

Eileen Herrera is an international affairs specialist with OIRP. She indicatesthat many projects focus on issues that affect productivity, trade between theUnited States and Mexico, and natural resources management along our sharedborder. She says OIRP recently completed a pilot program to exchange gradu-ate students and postdoctoral researchers between Mexico and the United States.She said the program not only increased cooperation between the neighboringnations, but it also had the added benefit of improving professional developmentwithin ARS, since the program emphasized participation from the agency’s early-career scientists.

Herrera says the latest direction in their relationship with Mexican researchinstitutions was to increase and enhance cooperation through a series of fiveworkshops, in partnership with INIFAP, ARS’s counterpart agency in Mexico.“The workshops are a mechanism for a more strategic approach to cooperationbetween ARS and Mexican research institutions,” Herrera says. “My hope isthat within the next few years, we will take what has already been a productiverelationship between scientists and their respective research locations and buildon it to make it more comprehensive at the agency level.”—By Jim Core, ARS.

Eileen Herrera is with the USDA-ARS Office of International Research Pro-grams, 2000 East Allen Rd., Tucson, AZ 85719; phone (520) 670-6380, ext.120, fax (520) 670-6493, e-mail eherrera@tucson.ars.ag.gov.

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Good for People Too?

Probiotics are good forpeople, too. All animalshave naturally occurringbeneficial probiotics intheir guts. One common-ly known probiotic, Lac-tobacillus acidophilus, isnaturally present infoods such as yogurt,grains, and meat prod-ucts. And prebiotics suchas inulin have been usedextensively—particular-ly in Europe and Japanwhere they’re now in-cluded in many foodproducts from sportsdrinks to baby formula.

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22 Agricultural Research/January 2004

“The biggest challenge is determiningthe correct types and quantity of pro-biotics because of the numbers anddiversity of microbes and the poorlyunderstood interactions between the

microbes and the intestine,” Donoghuesays.

So far the team has screened morethan 4 million enteric isolates to comeup with several promising probiotic

combinations. The University of Arkan-sas and ARS have filed a patent on theselection techniques.

A Test To Identify Probiotics“By using these preselected good mi-

crobes, we hope to produce inexpensive,defined cultures with the ability to re-duce or exclude specific pathogens andenhance enteric health in poultry,” Dono-ghue says. “We’ve developed multiplein vitro selection systems for identifica-tion of candidate organisms.”

When they find potential probiotics,the researchers test and identify the in-dividual microbes in their labs and sendthem to the Arkansas Livestock and Poul-try Commission’s diagnostic laboratoryin Springdale as a backup check. Theyalso test these individual isolates to elim-inate potentially harmful microflora byinjecting them into turkeys and chickensand evaluating these birds for lesions andrates of disease and death.

Donoghue says the organisms they areselecting are very easy to propagate inbatch culture, using inexpensive growthmedia. These bacteria are all facultativeaerobes, meaning that they are oxygentolerant. Producing such organisms on acommercial scale is expected to be muchless expensive than some cultures thatinclude strict anaerobes requiring com-plex equipment and technology.

This new method makes it much lessexpensive to produce probiotics. Thiscould both lower the price of poultry andmake it less likely to be a source of food-borne illnesses.—By Jim Core, ARS.

This research is part of Food Safety(Animal and Plant Products), an ARSNational Program (#108) described onthe World Wide Web at www.nps.ars.usda.gov.

Annie Donoghue is in the USDA-ARSPoultry Production and Product SafetyResearch Unit, Center of Excellence forPoultry Science, University of Arkansas,Fayetteville, AR 72701; phone (479)575-2413, fax (479) 575-4202, e-maildonoghue@uark.edu. ★

Annie Donoghue and graduate student John Holliman inspect plates to identify bacteriathat can inhibit Campylobacter growth. Candidate bacteria are placed in the center of aplate containing Campylobacter. Those that outcompete this pathogen form a clear zone(circle) of inhibition.

Memo Tellez adds a probiotic culture to the drinking water of turkey poults. This field trialis to test the culture’s ability to reduce foodborne pathogens and enhance growth and healthof the birds.

STEPHEN AUSMUS (K10914-1)

STEPHEN AUSMUS (K10912-1)

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