The problems and interesting facts about breeding poultry
autosomal trait :- a gene carried on a non-sex chromosome and present in two copies in both sexes.
sex-linked trait - a gene carried on the sex chromosome that is present in both sexes; one copy in one sex, two in the other. In mammals, this is the X chromosome (one copy in males, two in females).
In birds, this is the Z chromosome (one copy in females, two in males).
1. 1 st cross
(female)nonbarred x (male)barred -------- all barred
Therefore …….. nonbarred is recessive
2. Reciprocal cross
(female)barred x (male)nonbarred --------(female)nonbarred and (male)barred>
genotype : (female)Z B - W (barred) x (male)Z b - Z b (nonbarred) gives
1 ZBW : 1 ZBZb
ZbW is a nonbarred female (remember the female is heterogametic in birds)
ZBZb is a barred male
From this mating sexing chicks at birth is possible.
For the mating, ZBW x ZbZb, the progeny genotypic ratio is :
For the mating, ZBW x ZBZb, the progeny genotypic ratio is :
The difference is readily apparent and allows large numbers of male and female chicks to be separated quickly with a minimum of labor. Breeders must maintain genetic uniformity for the pertinent alleles in their male and female parent lines, to take advantage of the opportunity to feather-sex chicks.
a - Where trait exists in only on one of the two sexes can occur at single-locus level (long feathers in chickens)
example: feather length in chickens
females all have short feathers
in males, s+s+ and s+s = short feathers
ss = long feathers
click here to see a picture of the difference in feathering
b - more common at the multiple-gene level involving complex traits (e.g., egg laying)
A. Expression of a phenotype is limited to one sex
B. Gene is NOT on a sex chromosome
C. Example – domestic fowl tail and neck plummage.
In the males, cock-feathering is more long and curved, while in the female, hen-feathering is more short and rounded.
S > s : silver > gold
Parents: SS Male x s- Female
F1 Progeny: Ss and S- offspring all silver
ss Male x S- Female
F1 Progeny: Ss silver males
s- gold females
Parents: dw dw x DW-
F1 Progeny: DW dw Male and dw - Female
Application: normal sized Male x dwarf females
The dwarf gene has pleiotropic effects:
• 20% smaller body weights
• 20% less feed consumption
• less eggs
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This site is being created and maintained by
Jill Bowis of Kintaline Poultry and Waterfowl Centre, Benderloch, OBAN Argyll PA37 1QS Scotland
for the utility poultry breeders everywhere
Any useful information you have for the site is gratefully received
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