Gerry Huff, microbiologist with USDA's Agricultural Research Service (ARS) in Fayetteville, Ark., and her colleagues have been studying the effects of yeast extract as an immune stimulant and alternative to antibiotics in conventional turkeys. Huff, who works in the ARS Poultry Production and Product Safety Research Unit (PPPSRU) in Fayetteville, said non-pharmaceutical remedies and preventatives are particularly needed for organic poultry production.
Dietary yeast extract has good potential as a non-antibiotic alternative for decreasing pathogens in organic turkey production, initial studies suggest. A larger study was needed to confirm its efficacy.
However, it is expensive to work with turkeys because they eat more than other birds, Huff said. So the researchers are using yeast extract in Japanese quail to test the extract's efficacy against Salmonella and Campylobacter. The quail serve as a model system to evaluate natural treatments that will be beneficial for chicken and turkey production.
Huff's current study, in collaboration with Irene Wesley at the ARS National Animal Disease Center in Ames, Iowa, involves 800 Japanese quail.
She explained yeast extracts help boost the immune system's ability to kill bacteria, but there is also a downside. Yeast ramps up certain aspects of the immune response, but body weight may be decreased in some birds because the energy normally used for growth is redirected toward the immune system. As a result, the researchers are looking for a balance between enhancing immune response and maintaining growth.
Regarding organic production, organic poultry farms can only use compounds on the National List of Allowed and Prohibited Substances. Yeast extract is on that list.
Antibiotic alternatives are also needed for conventional poultry production, because regulations for the usage of antibiotics are being tightened in response to the prevalence of antibiotic resistance in pathogens.