Breeding resistant chickens for improved safety

Researchers at the Agricultural Research Service (ARS) in Texas have identified roosters whose blood contains naturally high levels of two key chemicals, cytokines and chemokines, which mobilise the birds’ innate immune response.

Using the new tests, commercial poultry breeders can single out roosters that have a strong immune response and use them to selectively breed a more robust flock. Such resistance, particularly during the birds’ first week of life, may lower costs related to animal well-being and food safety.

Christi Swaggerty, ARS microbiologist, said protecting chickens from pathogens involves sanitation, vaccination, biosecurity and use of antibiotics and other medications. But some chickens have an especially robust and efficient immune response and can resist pathogens.

The researchers used the test to select roosters for breeding a line of resistant broilers. They then exposed the resistant broilers to several pathogens and compared the resistant group to a group of susceptible broilers bred from roosters with low cytokine and chemokine levels.

The results, published in Poultry Science, showed that the susceptible broilers had more pathogens and signs of infection than the resistant group. Ultimately, such resistance could mean fewer pathogens remaining on birds at the processing plant and improved consumer safety, according to Ms Swaggerty.

She and colleagues study the genetics of chickens’ resistance to foodborne disease causing pathogens, such as Salmonella and Campylobacter. Some species of these two bacteria together cause 2-3 million US cases of foodborne illness in consumers and 450-500 deaths annually.

Another poultry disease, Coccidiosis, is caused by a single-celled parasite Eimeria. In the US, the disease inflicts annual production losses of up to $800m, making this intestinal disease a significant threat to nearly 9 billion US meat-type birds.