The Inheritance of Plumage Color Patterns in Turkeys
Karl Nestor
The Standard of Perfection, a book published by the American Poultry
Association, Inc., characterizes breeds and varieties of poultry.
According to the Standard of Perfection, turkeys constitute a single
class of fowls and that is the breed. The turkey breed is subdivided
into several varieties. Turkey varieties included in the Standard of
Perfection and those not included are usually characterized by, among
other things, the plumage color pattern.
The bronze feather color pattern is the “wild type” for turkeys. With
this pattern, plumage on the neck and upper breast is black, the exposed
tips of the feathers are overlaid with iridescent, red-green bronzing.
Feathers of the lower breast, wings, and front half of the back is
similar to that of the neck but there is an edging of velvety black
added to the red-green bronzing. The feathers of the rear half of the
back have black undercolor and black surface color which is bordered
with a band of bronzing. The upper thigh feathers are like the above but
have an additional terminal edging of white. The exposed portion of the
tail feathers are black, evenly penciled with narrow strips of brown
near the end where there is a broad band of the brilliant, copper
colored bronzing.
Plumage color patterns other than the bronze are controlled by mutant
genes. Generally, these plumage color patterns are primarily due to a
single gene but the gene must be in the proper combination with other
genes. The genes responsible for turkey plumage color patterns may be
located on autosomal chromosomes or on the sex chromosome. The location
of the gene is important in how it is transmitted to the offspring. In
birds, unlike mammals, the male has one sex chromosome (ZZ) and the
female has two chromosomes (ZW). An autosomal gene, c, prohibits the
expression of any color resulting in white feathers. There is an allele
(located on the same spot on the chromosome) of the white gene, cg ,
responsible for the gray color. However, the expression of the cg gene
is greatly influenced by other plumage genes in the genetic background.
There are two plumage color autosomal genes that are dominant to the
bronze type; these are black (B) and slate (D). There is also a
recessive gene, sl, that produces the slate color. Other autosomal genes
include spotting (sp), black-winged bronze (bl), and bourbon red (r).
Two sex-linked recessive genes (Narragansett, n and dark brown, e)
influence plumage color patterns.
Some plumage color patterns in turkeys are the result of the interaction
of multiple genes. In this case, crossing of colored turkey varieties is
not as predictable. One of these is the Royal Palm. Also, some genes
that influence plumage color are highly detrimental to the bird. An
example of this type of gene is the sex-linked recessive albinism gene
(al) that is lethal to about 75 % of the females carrying it. Most
albinotic poults die within 6 weeks after hatching.
Research at The Ohio Agricultural Research Center attempted to determine
if various plumage color genes (B, r, sp, cg, D, bl, and e) had any
positive effects on growth rate and reproduction of the turkey. In most
cases, the bronze gene gave superior performance compared to the mutant
genes. The one exception was the cg gene that improved semen production
of the males without influencing growth rate. The sp gene was associated
with a high frequency of blindness.
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