Henny Feathering

Henny feathering (often called hen feathering) is a mutation in chickens that causes the males to grow in female plumage (1). It is caused by an increased level of estrogen and decreased levels of testosterone in the feather and skin cells of the chickens, which prevents the long hackle and saddle feathers typically seen in males (called benny feathering).

This hen feathering trait can be caused from a variety of things, including caponization and intersex birds on the male line (2)(6). It is also possible for hens to grow male plumage after damage to the ovaries and other estrogen tracts (4). However, unlike both of these, the henny feathering gene causes the males to grow out with hen feathering from chicks (7). Because the testosterone production is only decreased in the skin cells and not the testes, it also has little affect on the fertility of the bird (7). Females with either form of the gene do not have any noticable differences.

It is an incomplete dominant trait, though it appears dominant when test breeding (1). Male birds with only one copy of the gene will show higher levels of testerone in the skin, but still look completely henny feathered (1). While they will not have the long saddle or hackle feathers, they will have more testosterone in the skin cells than those with two copies of the henny feathering gene (3).

The APA recognizes Sebrights and Campines, both breeds that require hen feathering in the males. (8) Henny feathering has also been noted in Leghorns, and could be bred into any breed. It is also worth noting that because the gene only affects the appearance of the males, any female bird with henny feathering could be shown without disqualification.