Chickens selected for higher levels of natural antibodies have a higher immune response, this was discovered by researchers of Wageningen University & Research. This gives insight in possible mechanisms of these natural antibodies in general disease resistance, especially towards bacteria. Selection of chickens with an increased disease resistance is therefore one step closer to practice, and can ultimately result in reduced antibiotic use and animals with higher well-being.
In poultry housing systems, animals frequently get in contact with each other. A possible pathogen can, once present in a house, spread relatively easily among the animals. Already for decennia, the poultry industry is requesting robust animals: animals with a good resistance against diseases. One possibility to obtain this robust chicken is to breed animals with an increased disease resistance.
Selecting for natural antibodies
Animals have so-called natural antibodies. These antibodies are part of the immune system. Natural antibodies recognize pathogens in healthy animals, without previous exposure to this pathogen. They block and prevent further spread of pathogens, but also warn and activate other parts of the immune system. Earlier studies showed promising results: natural antibody levels are heritable and can therefore be altered by breeding. Also, higher natural antibody levels were associated with a higher survival. Researchers from Wageningen University & Research put this to the test and selected layer chickens for high or low natural antibody levels.
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Protection by natural antibodies
To get better insight in the general protection of natural antibody, layer chickens were selected for high or low natural antibody levels for two generations. The layer hens of the second generation were vaccinated with one of three different vaccines. Tom Berghof, main investigator of this study, explains: “We used vaccines that cause different immune responses: one immune response is directed against bacteria, one immune response is directed against viruses, and one immune response was specific for our selection on natural antibodies.” Animals with high natural antibody levels had, compared to animals with low levels, a higher antibody response against the bacterial vaccine, but not to the other vaccines. Berghof: “This suggests that animals with higher natural antibodies might have a better protection against bacterial diseases.”
Application and future plans
This study offers a hopeful perspective to breed chickens on natural antibody levels to improve general disease resistance, especially towards bacteria. “But first we want to know more about the selection on natural antibodies, so we will continue the selection for a couple of generations more.” Berghof says. “In addition, we will investigate if the lines also respond different to real bacterial pathogens, and if they differ in other forms of protection against, for example, viruses.” Eventually, this research could lead to animals with improved general disease resistance and lower antibiotics use, lower economic losses for the farmer and higher animal welfare.
Read the full article in Vaccine for more information.
Hendrix Genetics supplied animals for this research. This research is part of the research programme “Divergent selection for natural antibodies in poultry” (with project number 12208), which is financed by the Netherlands Organisation for Scientific Research (NWO).