Supplementing the diets of live turkeys with vitamin E
may reduce the already small chance of transmission of a serious foodborne
That's the finding of an ARS
study conducted on the birds that was aimed at controlling Listeria
monocytogenes, a major human bacterial foodborne pathogen found
Microbiologist Irene Wesley of the ARS National Animal
Disease Center (NADC) in Ames, Iowa, says dietary supplementation with
vitamin E stimulates live turkeys' immune responses and enhances clearance
of the microorganism from the gut.
"This can reduce contamination of carcasses at slaughter
and during processing," says Wesley, who conducted the study at
NADC's Pre-Harvest Food Safety and Enteric Diseases Research Unit, with
help from collaborators from the University of Arkansas and Iowa State
Turkeys can be infected with L. monocytogenes through
contaminated feed or water and carry it in their intestines into packing
plants, where it can spread. In a 1998 U.S. Department of Agriculture
study, L. monocytogenes was found in nearly 6 percent of turkey
carcass rinses and 31 percent of ground turkey meat examined.
The microorganism causes listeriosis, a disease that affects
mainly pregnant women, newborns, and adults with weakened immune systems.
It accounts for 2,500 cases annually of human meningitis, encephalitis,
sepsis, fetal death, and premature births. Its mortality rate of 25
percent is the highest among foodborne illnesses.
Wesley says vitamin E "boosts the immune response,
boosts T-cells," the white blood cells that activate when disease-causing
organisms are detected. "Vitamin E gets those guys revved up. It's
like putting high-octane gasoline in a motorcycle."
Breaking New Ground
She says that in addition to examining how vitamin E affects fowl,
the study also marked the first attempt to correlate dietary vitamin
E with changes in virulence of bacterial foodborne pathogens, the dynamics
of lymphocyte subpopulation, and subsequent clearance of L. monocytogenes
in any animal species, including turkeys.
The workaided by graduate student Meijun Zhu and faculty members
Aubrey Mendonca and Dong Ahn from Iowa State; and postdoctoral fellow
Rama Nannapaneni, technician Mandy Cox, and professor Michael G. Johnson
of the University of Arkansasinvolved two sets of experiments
in which day-old turkeys were fed varying doses of vitamin E and inoculated
with L. monocytogenes 6 weeks later. A control group that was
not fed the vitamin was also inoculated at 6 weeks old. These studies
have been accepted for publication in the journal Poultry Science.
Poultry requires vitamin E for normal development and function of the
immune system. Wesley used alpha-tocopherolthe most active form
of vitamin E in humans and a powerful biological antioxidantbecause
it is readily available from commercial sources and can be used in animal
Earlier tests conducted by Ahn at Iowa State showed that dietary vitamin
E also enhances poultry meat's quality and shelf life.
Wesley says that after further confirming these findings, she plans
to test vitamin E against Salmonella and Campylobacter,
two other important foodborne pathogens.By Luis
Pons, Agricultural Research Service Information Staff.
This research is part of Food Safety (Animal and Plant Products),
an ARS National Program (#108) described on the World Wide Web at www.nps.ars.usda.gov.
Irene V. Wesley is
with the USDA-ARS National Animal
Disease Center, 2300 Dayton Rd., Ames, IA 50010-0070; phone (515)
663-7291, fax (515) 663-7458.
"Vitamin E May Be Key to Safer Fowl" was published
in the January
2004 issue of Agricultural Research magazine.