الفهرس 
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Abstract
This study aimed to decrease the cost of the laying rations by lowering protein as it’s the most
expensive constituent in the diet. So the research stated to investigate the effect of
incorporating protease and/or formic acid as feed additives into low protein isocaloric diet of
laying Japanese quail hens on the productive performance, egg quality, some serum
biochemical parameters and carcass traits. It was performed on 120 of 5-6 week old healthy
Japanese quail hens (weighed 268g±7.06) and randomly distributed into five groups (3
replicate per group). G1 (control with basal layer quail diet 20% protein), G2 (17%protien
diet without protease enzyme or formic acid), G3 (17% protein diet + 0.05%protease
enzyme), G4 (17%protein diet + 0.5%formic acid), G5 (17% protein diet + 0.05% protease +
0.5% formic acid). The experimental period lasted for 12 weeks with two weeks of adaptation
before this period. For each replicate, daily egg number, daily egg weight and egg mass as
well as weekly feed intake were recorded. At the end of each week, eggs were collected from
each replicate to evaluate egg quality. Mean egg production, shape index, egg albumin
weight, egg shell weight, egg yolk percent, carcass traits and most measured blood parameters
in all groups had not differ significantly with control but G2 was numerically higher than
control in egg production, egg mass, FCR, egg shell weight, albumin weight, egg yolk weight,
dressing percentage, feed intake and weight losses at the end. G2 significantly has the heavier
egg weight among groups (p<0.05) as the average egg weights were 11.77g and 12.48g in
control and G2 respectively. G3 was the highest in feed intake and egg albumin percent
among the other groups. G4 was the highest in egg shell percent. Triglycerides per whole yolk
were lower in all groups than the control. Cholesterol (mg)/whole yolk was low in G2 and G3.
FCR was improved in G5. G2 had the highest net revenue and economic efficiency (48
LE&114.3%) in compare with control (46 LE&106.98%), while the values were
47.1LE&107.3%, 43.3LE&101.4% and 46.2 LE&105.5% for groups G3, G4 and G5
respectively. It could be concluded that, feeding laying Japanese quail hens on diet containing
17% protein without protease or formic acid did not differ significantly than those on control
diet containing 20% protein. Moreover, it showed numerical improvement than the control
group regarding egg production, egg mass, FCR, egg shell weight, albumin weight, egg yolk
weight, cholesterol in egg yolk and dressing percentage. Also, the low protein diet without
any additives has the highest net revenue.