Adding oil or spice to the diets of chicks may help stave off intestinal parasites that cause avian coccidiosis, studies by Agricultural Research Service scientists suggest.

Coccidiosis is caused by single-celled organisms of the genus Eimeria. These microbes infect the chick's intestine and cause lesions that hinder the chick's ability to absorb nutrients from feed. This can slow the chick's growth or kill it. Coccidiosis costs poultry producers $350 million annually in losses and medication expenses for antibiotic drugs such as salinomycin.

A search for new alternatives for Eimeria control has been spurred by the microbe's increasing resistance to available drugs, the cost of developing new drugs, and growing consumer demand for drug-free poultry.

To this end, researchers at ARS' Parasite Biology and Epidemiology Laboratory in Beltsville, Md., are testing new, natural feed additives: high-fatty-acid oils from flaxseed and linseed plants. The additives don't kill Eimeria. Instead, they trigger a natural, biochemical response in chicks called oxidative stress. The stress results in byproduct compounds that doom Eimeria hiding in cells of the cecum, a portion of the bird's small intestine.

When mixed into a commercial diet and fed to newborn chicks for four weeks, flaxseed oil reduced by 54 percent the number of cecal lesions caused by the species E. tenella. A linseed oil diet reduced lesions by 64 percent.

Also of interest to the scientists is cucurmin, an antioxidant from turmeric, a popular cooking spice used in curries and other ethnic foods. Turmeric targets protozoa infecting the mid-gut. Compared to untreated control birds in the study, turmeric-fed chicks had 58 percent fewer lesions from E. maxima. Turmeric also increased the chicks' weight by 35 percent.

E. tenella and E. maxima are just two of seven Eimeria species researchers hope to fight with the new approach.

Scientific contact: Patricia Allen, ARS Parasite Biology and Epidemiology Laboratory, Beltsville, Md., phone (301) 504-8772, PALLen@ggpl.arsusda.gov.