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Abstract
Newly hatched male chicks from layer breeders are usually killed immediately after hatching. Killing could easily be avoided if only female chicks were born. Now the “sex” of the chick embryo is determined at 6-7 days of egg incubation. Injection of Fadrozole an aromatase inhibitor that inhibit formation of estrogen from testosterone. at day 4 of incubation causes the formation of testicular tissue in female embryos but has no effect on sex chromosomes
Previous stu4ies showed some spermatogenic activity of testis of sex reversed hens . The aim of the present study is to improve the spermatogenic process in those neo males to obtain sperms with W or Z chromosomes.It is assumed that pairing of ZW neo male and ZW control female would produce W W females . Pairing of WW females with ZZ males will produce all female ZW progeny
.
Experimental design.
Experimental birds:
Local breed (Gimmizah strain) chicks were used in the present
study. This breed is characterized by sex linked feather color.
Egg incubation
One hundred and twenty eggs
conditions .On day 4 of incubation
fertile eggs were used for injection
Ninety five (95 ) fertile eggs were
injected as the following :-
Egg Treatment:
Group 1: Thitty-five- eggs (35) were injected with ( 0.1 ml) of phosphate buffer saline( PBS) alone to be considered s control
Group 2: sixty eggs ( 60) were injected in this group
Each egg was injected with 0.lml of PBS containing (1mg)
Fadrozole.
Out of the 95 injected eggs used m the present study, 56 chicks hatched (58.9% hatchability), 23 chicks hatched from eggs injected with PBS as control ( 65.7 % hatchability ) , 33 chicks from eggs treated with Fadrozole (55 %hatchability). All chicks were reared lii floor pens up to 28 weeks of age and fed daily with a standard diet prdvided 4 libitum.
At 4 weeks of age chicks were sexed according to the feather color and the secondary sex characters (size of comb and wattles) and divided into two groups as the following
Control chicks: Include 12 females and 11 males (hatched from eggs injected with PBS alone).
Chicks hatched from Fadrozole injected eggs): Include:11 males and 22 phenotypic males (sex reversed females or neomales) .These phenotypic males were either kept on
control diet for 28 weeks of age (n=1 1 birds). or received oral dosages of
L — tyrosine 100mg \ kg .Ration In the ration once per week from the
4 to the 28 weeks of age (n=’l I birds).
A number of birds from each group were sacrificed by slaughtering at
16 weeks old and the remaining chicks were sacrificed at 28 weeks old.