الفهرس 
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Abstract
In the present study the bacteriological examination of 1272 samples collected from 2 broiler beerder farms and one hatchery located at Kalyobia Governorate was carried out to deal mainly with different possible sources of E.coli infection as well as bacterial contamination on hatching eggs. The obtained results cleared that.
1-Total Bacterial Count:
vSignificant differences in mean T.B.C. of samples collected
from farm I and those from farm II.
•Significant differences in mean T.B.C. of samples collected
during summer and those collected during winter.
vNo significant differences in mean T.B.C. of samples collected at 30th week and those collected at 50th week, also no Significant differences in T.B.C. of samples collected at 55th week and those collected at 60th week of age.
Significant differences in mean T.B.C. of water samples collected from drinkers and those collected from main water tank .
Significant differences in mean T.B.C. of feed samples collected from feeders and those collected from feed bags.
vSignificant differences in mean T.B.C. among samples collected from different sites (litter, feed, water, dust, and egg nests litter).
Significant differences in mean T.B.C. among eggs collected from different site, except no significant differences in mean T.B.C. of eggs/shell that collected from nest and those collected from egg storage room. Also no Significant in mean T.B.C. of eggs /shell collected after pre-storage fumigation and those
collected pre-incubation fumigation. 2-Coliform Count (C.C.):
Significant differences in mean C.C. of water samples collected from main water tank and those collected from drinker. No seasonal variation in mean C.C. was reported water samples collected during summer and those collected during winter. Also no significant differences in mean C.C. between samples collected from farm I and farm II.
3-Incidence of E. coli recovered from samples collected from two broiler breeder farms and one hatchery:
from a total of 588 samples collected from 2 farms, 203 samples (34.52 %) yielded E. coli isolates while from a total of 684 samples collected from hatchery, 200 samples (29.2 %)yielded E.coli isolates .
a-incidence of E. coli recovered from boiler breeder farms:
Incidence of E.coli recovered from litter, eggs nests litter, wall dust, feed, water,air, worker hand swabs and cloacal swabs were 72.2 %, 47.2 %, 50 %, 22.2 %, 20.8 %, 58.33 %, 47.2 % and 75 % respectively.
Incidence of E. coli recovered from hatching eggs collected from nest, after pre-storage fumigation and eggs from egg storage room were 44.4 %, 19.4 % and 30.5 % from egg shells, while zero., 8.33% and 13.8%
from egg contents respectively.
b-Incidence of E. coli recovered from environmental samples collected from the hatchery:
Incidence of E.coli recovered from air, water, wall ,floor, egg trays swabs, chick box swabs, worker hand swabs and fluffs of newly-hatched chicks collected from the hatchery were 37.5 %, 25.0 %, 29.16 %, 45.8 %, 25.0 %, 33.3 %, 36.1 % and 63.8 % respectively.
c-Incidence of E. coli recovered from hatching eggs and newly hatched chicks collected from the hatchery:
Incidence of E. coli recovered from hatching eggs collected after pre-incubation fumigation, infertile eggs, eggs at 19th day of incubation, eggs dead in shell embryos were 19.4 %, 33.3 %, 25.0 % and 41.66 % from egg shells, while 13.8 %, 25 %, 19.4 % and 30.5% from egg contents respectively. In addition to that incidence of E. coli recovered from heart blood and yolk sac of newly- hatched chicks were 19.4 % and 16.6 %’respectively.
4-E. coli serogroups recovered from samples collected from
boiler breeder farms:
from the obtained result it can be demonstrated that E. coli serogroup 0127 was the most prevalent (16.25 %) among the typed isolates collected from two broiler breeder farms , followed in order by 0125 (15 %) , 078 (10 %) , 0126 and 086 ( 7.5 % each ) , 0119 (6.25 %) , 0128 and 055 (5 % each ) 0114, 0111 and 026(3.75 % each ) and untypable serogroups (16.25 %).