الفهرس 
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Abstract
An experiment was conducted to compare the effects of three organic
selenium (Se)
sources with four levels of supplementation on growth performance and carcass
characteristics, selenium contents in feather, blood, liver, front and rear meat ,
GSH-PX activity, lipid peroxidase (TBA) and thyroid hormones of Japanese quail
chicks. Three hundred and sixty (straight run) unsexed chicks of Japanese quail
were individually wing-banded and placed in groups of ten chicks at seven days of
age, for a 28-day experiment. In all experimental treatments, chicks were kept as
possible under similar managerial and hygienic conditions. The experimental diets
were supplemented with organic Se yeast and mixed with the common basal diets
(at 0.1, 0.3 and 0.5 mg Se/kg of feed). Residual feeds were weighed back weekly,
and weekly feed consumption was calculated.
The experiment utilized a 3 x 4 x 3 factorially arranged completely
randomized statistical design. Se was supplemented to the diets as the following
design and the background levels of Se were analyzed in the tested diets. Each
treatment was replicated three times. Each replicate consisted of ten chicks per
replicate.
The following results were obtained:
Availa had heavier live body weight at 35days of age (LBW35), and higher
estimates for either pooled daily gain or growth rate (PDG; PGR) and better feed
conversion during the periods: 21-28, 28-35 and 7-35 days of age and had the
highest performance index than other sources. Insignificant differences due to level
of supplementation were found for LBW’s at all ages studied, PDG during all tested
periods of growth. Availa 0.5 had the highest LBW35, daily gain during the periods
14-21 and 7-35 days of age, PGR during 21-28, 28-35 and 7-35 periods and had
higher total revenue. As Se level increased, both the price/kg feed and feed cost
increased. Either economic efficiency or relative economic efficiency (EEf or
REEf) for 0.1 level insignificantly differed than the control and significantly
differed than both 0.3 and 0.5. Availa 0.3 and 0.1 had significantly higher EEf (4.25
and 4.24 ) and REEf (107.06 and 104.00 than other source level groups. Neither
source of organic Se nor level of supplementation and Source x Level significantly
influenced each of individual absolute carcass parts, relative carcass parts(%) to
live body weight and chemical composition traits. Results of this study revealed
that the dietary Se supplied in an organic form as Availa with the levels of
supplementation 0.1 and 0.3 can be used to improve Se status in Japanese quail
which may led to greater resistance to oxidative stress and resulted in higher
LBW35, Pooled gain7-35, EEf or REEf and performance index than other sources by
levels without deteriorations in performance traits . This greater resistance to
oxidative stress may improve meat quality.
Key words: Organic selenium, levels, performance, glutathione peroxidase, T3,
T4, T3/T4, TBA , Japanese quail.