الفهرس 
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Abstract
This work was designed to study the effect of dietary protein levels, dietary regime systems and supplementation of the diet with methionine on growth performance of J. quail. Therefore three connected experiments were carried out. Increasing the dietary protein level up to 28% increased the average body weight during the first four weeks of growing period, while at end of the experiment, there were no significant differences in average body weight between the groups fed diets contained 24, 26 or 28% crude protein,
- Maximal weekly gain values obtained at the third week of age for the groups fed diets contained 24, 26 or 28%CP, while the maximal weekly gain for the groups fed 20 or 22%CP-diets was delayed to the fifth week of age.
-Increasing the dietary protein level up to 28% resulted in decreasing the amount of feed intake and improved the efficiency of feed utilization.
-Increasing the dietary protein level increased the amount of protein intake/bird, while the protein efficiency ratio was decreased.
-Mortality rate of Japanese quail during the growing period was not affected by dietary protein level and most of mortalities were recorded during the first two weeks of age.
- The protein level in the diet had no significant effect on percentages of the dressed carcass or total edible carcasses.
Experiment II:
This experiment was designed to evaluate the effect of using different regime systems depending upon decreasing the dietary protein level at different periods of the age throughout the growing period on growth performance of J. quail. Two hundred and fifty quail chicks (one day old) were divided into five equal duplicate groups, The first group (control) was fed a diet contained 28% crude protein throughout the whole experimental period. While each of the other four groups fed three isocaloric diets (2850 Kcal ME /Kg) contained different levels of protein (28, 24 or 20%) for different periods of age. Body weight; body gain; feed intake; feed conversion ratio; protein intake and protein efficiency ratio were measured. Results of this experiment revealed the following:
Body weight increased by increasing the number of weeks before shifting the birds to the low-protein-diet (20%). The body weight and the gain for quail group fed the 28% CP-diet for the first three weeks of age, 24% CP-diet for the next two weeks and 20% CP-diet during the last week did not differ significantly from those of the group fed the 28% CP-diet throughout the whole growing period.
- Feed consumption for the control group was significantly
lower than that of other groups and the feed intake increased by increasing the period in which the birds received the low protein-diet (20%).
-Feed conversion ratio increased (less efficient) by increasing the period of feeding the low-protein-diet (20%) and the least feed conversion ratio among the groups received the different dietary regimes was recorded for the group received 28% CP-diet during the first three weeks of age, 24% CP-diet during the next two weeks and 20% CP-diet during the last week of the experiment.
-The least cast of feed per 100 g body gain among the quail groups was recorded for the group received the 28% CP-diet during the ].st three weeks of age, 24%CP-diet during the next two weeks and 20%CP-diet during the last week of the experiment.
-Mortality percentage were not affected by dietary regime systems.
-Collectively, maximum gain in live body weight with less feed cost per gram of gain among groups received the different dietary regime systems was recorded for quail group fed the high-protein-diet (28%) for the first three weeks of age, 24%CP-diet during the next two weeks and 20% CP-diet at the last week of growing period.
Experiment III:
The experiment was conducted to study the effect of supplementation a 24% CP-diet with methionine on growth performance of Japanese quail. One hundred and fifty quail chicks (one day old) were divided into three equal duplicate groups. The quail groups fed the 24% CP-diet supplemented with L. methionine (0, 0.1 or 0.2%) through-out the whole experimental period (6 weeks). Body weight, body gain, feed intake, feed conversion ratio and protein efficiency were measured weekly.
Results of this experiment can be summarized into the following:
- Supplementation of the 24% CP-diet with 0.1% L. methionine resulted in significant (P<0.05) higher body weight and body gain with significant improvement of the feed
conversion ratio.
-Supplementation of the 24% CP-di.et with 0.1% methionine resulted in a significant increased of protein efficiency
ratio,
-Mortality percentages were not affected by methionine supplementation.
-Addition of 0.1% L. methionine to the 24% CP-diet resulted in growth performance (body weight; body gain and feed
conversion ratio) similar to that obtained by feeding the quail on 28% CP-diet.
- Generally, supplementation of the 24% CP-diet with 0.1% methionine to obtain a dietary methionine level of 0.6% resulted in significant improvement of growth performance of Japanese quail and could reduce the high protein requirements by about 4%.