Featured Research

from universities, journals, and other organizations

Pigs Raised Without Antibiotics More Likely To Carry Bacteria, Parasites

Date:
June 12, 2008
Source:
Ohio State University
Summary:
While consumers are increasing demand for pork produced without antibiotics, more of the pigs raised in such conditions carry bacteria and parasites associated with food-borne illnesses, according to a new study. A comparison of swine raised in antibiotic-free and conventional pork production settings revealed that pigs raised outdoors without antibiotics had higher rates of three food-borne pathogens than did pigs on conventional farms.

While consumers are increasing demand for pork produced without antibiotics, more of the pigs raised in such conditions carry bacteria and parasites associated with food-borne illnesses, according to a new study.

Related Articles


A comparison of swine raised in antibiotic-free and conventional pork production settings revealed that pigs raised outdoors without antibiotics had higher rates of three food-borne pathogens than did pigs on conventional farms, which remain indoors and receive preventive doses of antimicrobial drugs.

“Animal-friendly, outdoor farms tend to have a higher occurrence of Salmonella, as well as higher rates of parasitic disease,” said lead study author Wondwossen Gebreyes, associate professor of veterinary preventive medicine at Ohio State University.

More than half of the pigs on antibiotic-free farms tested positive for Salmonella, compared to 39 percent of conventionally raised pigs infected with the bacterial pathogen. The presence of the Toxoplasma gondii parasite was detected in 6.8 percent of antibiotic-free pigs, compared to 1.1 percent of conventionally raised pigs. And two naturally raised pigs of the total 616 sampled tested positive for Trichinella spiralis, a parasite considered virtually eradicated from conventional U.S. pork operations.

As long as pork is cooked thoroughly according to federal guidelines, the presence of these infectious agents in food animals should pose no risk to human health. The U.S. Department of Agriculture recommends that consumers cook fresh pork to an internal temperature of 160 degrees Fahrenheit. The pathogens generally do not cause illness in the animals.

Gebreyes noted that routine antibiotic use does not fully prevent the occurrence of Salmonella bacteria even in conventional pig herds, as shown by the 39 percent of those pigs in this study that tested positive for the pathogen. By comparison, 54 percent of antibiotic-free pigs tested positive for Salmonella.

Gebreyes won’t recommend one type of pork production practice over another.

“We are just doing the science and showing the results,” he said. “Does having an antibiotic-free and animal-friendly environment cause the re-emergence of historically significant pathogens? I think that is an extremely important question for consumers, policymakers and researchers to consider.”

The study is published in a recent issue of the journal Foodborne Pathogens and Disease.

On conventional farms, pigs remain indoors in ventilated barns and have free movement within pens. Antibiotics are added to their feed to promote growth and protect against infections, followed by a withdrawal period before slaughter to ensure the meat doesn’t contain any antibiotic residue.

On antibiotic-free farms, pigs are reared in open fields with free access to soil and water. They are given antibiotics only for treatment against active infections, and once sick pigs are treated, they are separated from the herds and no longer marketed as naturally raised pork.

The scientists tested pigs on farms in North Carolina, Ohio and Wisconsin. Of the total studied, 324 were raised in antibiotic-free systems and 292 lived on conventional farms. The researchers took blood samples to test for the presence of antibodies against bacterial and parasitic infections. The higher rates of infection on natural farms were consistent in all three geographic regions.

Of the three pathogens studied, the positive tests for the Trichinella roundworm surprised researchers the most. Gebreyes said federal inspectors might expect to find one positive test for the parasite among more than 14,000 pigs, so the two positive tests among 600 pigs were significant.

The infection resulting from this parasite, trichinellosis, has historically been associated with undercooked pork, but in the recent past, the parasite has been associated mostly with wild mammals. People with this infection typically experience diarrhea, vomiting, fatigue and fever first, followed by headaches, cough, and aching joints and muscle pains. The symptoms can last for months, and severe cases can be fatal, according to the Centers for Disease Control and Prevention.

Prescription drugs are available to treat the infection.

The nearly 7 percent of naturally raised pigs infected with Toxoplasma, while a relatively small number, still represented a significantly higher infection rate than that found in the conventional herds.

Most people with a functioning immune system can resist symptoms associated with infection by Toxoplasma, which is considered most risky for pregnant women and those with compromised immune systems.

Salmonella is a common cause of food-borne illness, typically causing diarrhea, fever and abdominal cramps that resolve within a week and rarely require treatment in healthy people. More than 1 million people are infected by Salmonella in the United States each year, according to the World Health Organization.

Gebreyes noted that routine antibiotic use does not fully prevent the occurrence of Salmonella bacteria even in conventional pig herds, as shown by the 39 percent of those pigs in this study that tested positive for the pathogen. By comparison, 54 percent of antibiotic-free pigs tested positive for Salmonella.

“The advantage of using antibiotics is to prevent these infections from occurring. The disadvantage is it appears to create a favorable environment for strains of the bacteria that are resistant to antibiotics,” he said. “On the other hand, when antibiotics are not used, the pigs tend to get less resistant bugs, but higher rates of the common bacteria of food safety concern. The prevalence of Salmonella was significantly higher in the antibiotic-free herd than in the conventional herd. That could cause concern down the road about eating this product.”

The researchers theorized that naturally raised pigs’ exposure to moisture, vegetation and other animal species could contribute to their higher rates of pathogens. This study is part of a comprehensive examination of food safety issues related to pork production that includes testing pigs for a broader range of disease-causing organisms.

This work was funded by a grant from the National Pork Board.

Co-authors of the study were Peter Bahnson of the University of Wisconsin School of Veterinary Medicine, Julie Funk and James McKean of the College of Veterinary Medicine at Iowa State University, and Prapas Patchanee of Ohio State’s Department of Veterinary Preventive Medicine.


Story Source:

The above story is based on materials provided by Ohio State University. Note: Materials may be edited for content and length.


Cite This Page:

Ohio State University. "Pigs Raised Without Antibiotics More Likely To Carry Bacteria, Parasites." ScienceDaily. ScienceDaily, 12 June 2008. <www.sciencedaily.com/releases/2008/06/080611144016.htm>.
Ohio State University. (2008, June 12). Pigs Raised Without Antibiotics More Likely To Carry Bacteria, Parasites. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2008/06/080611144016.htm
Ohio State University. "Pigs Raised Without Antibiotics More Likely To Carry Bacteria, Parasites." ScienceDaily. www.sciencedaily.com/releases/2008/06/080611144016.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Cambodian Capital's Only Working Elephant to Retire in Jungle

Cambodian Capital's Only Working Elephant to Retire in Jungle

AFP (Nov. 25, 2014) Phnom Penh's only working elephant was blessed by a crowd of chanting Buddhist monks Tuesday as she prepared for a life of comfortable jungle retirement after three decades of giving rides to tourists. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Buzz60 (Nov. 24, 2014) A Swedish Adventure racing team travels to try and win a world title, but comes home with something way better: a stray dog that joined the team for much of the grueling 430-mile race. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins