Description:
Split wing, or a gene that causes the absence of the axial feather on one or both of the wings in poultry (4), is an under-researched mutation in the industry. It is believed by breeders to have a simple recessive inheritance (5), making it hard to breed out of flocks. This has not been confirmed in a lab.
The axial feather itself is crucial to the structural development of the wing, as one of the first parts of the wing to develop on the embryo (3)(4). It is important enough that the APA considers almost all split wing to be a disqualification (4).
Interestingly enough, it has been shown that having two copies of split wing increases the overall growth and carcass traits of broilers (1). This may be the reasoning behind some breeds requiring the split wing. This study, one of the only of its kind to study the split wing itself, also found that males will have a more drastic change because of the split wing than females would (1), suggesting the trait is at least partially sexually dimorphic.
The APA only recognizes split wing in the Ko Shamo and Aseel (4) though it is naturally found in the O Shamo and Nankin Shamo as well. It is considered a disqualification in all other breeds.
References & Further Reading
Samita Saini, Samita Saini, and I. S. Bajwa. "Incidence of split feathers and its association with carcass, conformation and bilateral asymmetry traits in male broiler chicken." (2015): 429-433.
Kondo, Mao, et al. "Flight feather development: its early specialization during embryogenesis." Zoological letters 4 (2018): 1-11.
Prum, Richard O. "Development and evolutionary origin of feathers." Journal of Experimental Zoology 285.4 (1999): 291-306.
American Poultry Association. (2023). American Standard of Perfection (45th ed.)
"Split Wing in Chickens." Once Upon a Chicken, https://onceuponachicken.com/split-wing-in-chickens/. Accessed 20 July 2024.
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