genetic resistance to hpai in poultry
Here on our farm, we kept a very genetically diverse flock. 12 breeds of ducks were used in our breeding program as we worked to develop a new breed of exceptionally productive pastured egg producers.
Thanks to the accidental delay in our test results, we were able to see what happened as HPAI progressed through first our pet flock, then each of our production flocks.
While our farm is too small of a sample to draw any firm conclusions, we saw intriguing suggestions that some breeds of duck were more or less vulnerable to HPAI.
POULTRY DISEASE RESISTANCE
Curious about this, I began looking into the scientific data. While the USDA had told us that no breeds show resistance, that proved to be false - there are many studies showing varying degrees of innate resistance to HPAI among many poultry species.
Some breeds and even some different lines of breeding within a single group unequivocally show a genetic component to HPAI resistance that is present in some birds and not in others.
Here is a sampling of studies showing genetic resistance to HPAI in some breeds:
“Among these breeds, Chee, Dang, and LHK showed significantly longer survival times than White Leghorns. Virus shedding from dead Thai indigenous chickens was significantly lower than that from White Leghorns”
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153649
“This study confirms that resistance to HPAI is a complex, polygenic trait and that mechanisms of resistance may be population specific”
https://www.sciencedirect.com/science/article/pii/S0032579119304390
“Resistant Ri chickens showed higher antiviral activity compared to susceptible Ri chickens”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9271386/
“This version of the influenza virus doesn't affect "broilers" — chickens raised for meat — as badly it does "layers" — table-egg laying hens — and turkeys.”
https://www.npr.org/2022/12/02/1140076426/what-we-know-about-the-deadliest-u-s-bird-flu-outbreak-in-history
This has been studied so well, in fact, genetic resistance to HPAI has even been found in mice:
“Although viral factors almost certainly play a role in limiting human infection and disease, host genetics most likely contribute substantially.”
https://journals.asm.org/doi/full/10.1128/JVI.00514-09
Why seek genetic resistance?
Studies has found that not only do resistant birds fail to show as many symptoms, they shed the virus less and can therefore break the chain of infection:
https://www.thepoultrysite.com/news/2016/07/genetic-resistance-offers-potential-breeding-solution-to-bird-flu
Taking it further, several studies already outline exactly how we can approach breeding birds for H5N1 resistance:
https://link.springer.com/article/10.1134/S0026893310010061
https://www.mdpi.com/1999-4915/4/11/3179
Does that mean my birds will survive if infected, too?
That depends on a lot of factors. Most importantly, I want to emphasize that what we saw in our ducks does not apply to chickens, geese, turkeys, peafowl, pheasants, emus, or any other poultry.
Ducks, both wild and domestic, are naturally more resistant to this outbreak of HPAI than other species. All of our geese suffered terribly and died, displaying no resistance whatsoever to this awful virus. Chickens are, generally, much more susceptible to HPAI than ducks are, and usually every single one will die horribly if a flock becomes infected. Please, don’t dismiss the danger to YOUR birds just because so many of our ducks lived.
However, there are some birds, across many different species, who do have some genetic resistance to HPAI. We absolutely do need to use this natural resistance to improve our flocks, using smart breeding programs as outlined above.
We need to encourage the USDA - and ask our representatives to put pressure on the USDA - to change their elimination-only approach to controlling HPAI.
Culling all the birds hasn’t worked, and we need to work on prevention through smart strategies like breeding for genetic resistance to eliminate the threat HPAI poses to our birds.
Write, email, call, and make waves with your representatives today! Here’s how!