الفهرس 
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Abstract
The current study was conducted in special poultry farm (area of
120m2), Shibin El-Kom, Menoufia Governorate. The experiment was
extended from April to May 2014. The great object of this study was to
determine the effect of some environmental factors (both of litters and feed
forms) on productive and economical efficiency of broiler for two strains
(Cobb500 and Ross 308) at ages 7, 14, 21, 28 and 35 days. One density was
applied in open system, 10 birds / m2. A total number of 1200, one day old,
unsexed, commercial broiler chicks, Cobb 500 (600 birds) and Ross 308
(600 birds) were reared under similar managerial and hygienic conditions.
Chicks were individually weight and randomly assigned to 3 experimental
groups nearly similar in average body weight (40g) within each strain. The
birds of first second and third groups were fed on crumble, mash and pellet,
respectively. Each group was divided into 2 subgroup of 100 birds each, one
of which was reared on wheat straw as litter and the other on sawdust. The
light program was 24h (continuous). Chicks housed on floor with sawdust
and straw. Feed and water were available ad libitun during the experimental
period which lasted for 35 days.
All birds were fed the basal starter, (1-14 days of age, with 23% crude
protein and 3030 kcal ME/kg diet), grower (14-28 days of age, with 21%
crude protein and 3100 kcal ME/kg), and finisher ( 28 – 35 days), with 19%
crude protein and 3200 kcal ME/kg), according to NRC (1994).
- The studied traits were as follow:
1. Body weights at different ages,
2. Growth rates,
3. Weekly and cumulative feed consumption (FC),
4. Feed conversion ratio (FCR),
5. Weekly and cumulative mortality percentage (%),
6. Uniformity (UF),
The results and conclusions can be summarized as follow:
1. Ross strain had heavier average body weight compared with Cobb500
strain.
2. Birds were reared on straw had heavier average body weight compared
with that were reared on sawdust.
3. Birds were fed pellet had heavier average body weight compared with
both of mash and crumble.
4. Cobb500 strain had the highest average growth rate followed with Ross
strain.
5. Cobb500 strain had the highest uniformity rate followed with Ross
strain.
6. Cobb500 strain have the highest average cumulative mortality followed
with Ross strain.
7. Cobb500 strain had the highest average cumulative feed consumption
followed with Ross strain.
8. Crumble had a superiority in the average cumulative feed consumption
followed by mash and pellet.
9. It is clear that highly significant effect of strains, litters types, feed forms
and broiler ages was noticed on feed conversion rate.
10.Average feed conversion ratio at 7, 14, 2, 28 and 35 days of age were
1.07±0.002, 1.29±0.003, 1.44±0.002, 1.59±0.002 and 1.70±0.002,
respectively.
11.Ross strain had the highest average feed conversion ratio at followed
with Cobb500 strain.
12.Birds were reared on straw had a superiority on sawdust in the average
feed conversion ratio.
13.There were highly significant correlations and positive relationships
between body weight and both weekly mortality, cumulative mortality,
weekly feed consumption, cumulative feed consumption and feed
efficiency. However, there were highly significant correlations and
negative relationships between body weight and both growth rate and
uniformity.
14.Feed conversion ratio was recorded at 35 days of age for Ross strain and
straw litter, Ross strain and sawdust litter (1.67±0.017 %)followed by
Cobb500 strain and sawdust litter (1.72±0.017 %), then Cobb500 strain
and straw litter (1.73±0.017 %).
15.Ross strain with pellet feed form had the best feed efficiencies for all
ages compared to the Cobb500 strain and the other feed forms.
16.In general, from the obtained results Cobb500 strain had the highest
value was recorded for body weight at marketing age (35 days) with
mash feed, however, Ross308 had the highest value for body weight at
same age with crumble feed.
17.The lowest mortality % was recorded for Cobb500 with crumble feed
and reared on sawdust, however, The lowest mortality % was recorded
for Ross308 with mash feed and reared on straw.
18.The highest economical value was recorded for crumble feed for both of
Cobb500 strain and Ross308 strain
Conclusions:
from the results obtained from this study, it concluded that:
− For Cobb500 strain, mash feed had a higher body weight at marketing
age. But for Ross strain, pellet feed had a higher body weight at
marketing age.
− For Cobb500 strain and sawdust litter have a same lowest mortality %
value with Ross strain and straw litter.
− Ross strain fed on crumble, and Cobb500 strain fed on mash had lowest
mortality %.
− The best economic efficiency was obtained with pellet feed form for both
Cobb500 and Ross.