الفهرس 
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Abstract
SUMMARY
This experiment was carried out at the hatchry of the
International Poultry’ Company (Nobaria - Alexandria) and Poultry
Research Station belonging to the Department of Animal
Production, Faculty of Agriculture, Zagazig University, Benha
Branch.
It was aimed to study the effect of injecting with thyroid
hormone preparation (Eltraxin), antithyroidal drug (Carbimazole)
and growth hormone on chick’s embryonic development,
productive performance and some blood constituents as related to
the metabolic processes in broilers.
A total number of 1340 eggs from Arbor Acres parent breed
were used in this study. Eggs were divided into two divisions
according to the incubation relative humidity (48% and 52%). Eggs
of each division were then subdivided into ten groups, eggs of the
1st, 2nd and 3rd groups were injected with 0.05,0.10 and 0.15 ug
eltroxin, respectively, those of the 4th, 5th and 6th groups were
injected with 0.05, 0.10 and 0.15 mg carbimazole, respectively,
while eggs of the 7th, 8th and 9th groups were injected with 0.005,
0.02 and 0.04 LU. growth hormone, respectively. Eggs of the 10th
group were injected with distilled water and used as control group.
Each group were divided into two divisions, eggs of the first
division were injected just before incubation (into the air cell) and
those of the second division were injected at the 9th day of
incubation period (into the embryonic allantoice cavity).
All eggs were weighed on days 0,3,6,9, 12, 15 and 18 of
incubation. Weight loss was calculated by difference and expressed
as a percentage of the initial fresh egg weight.
Embryonic mortolity was calculated during the incubation
period and experised as a percentage of fertile eggs and classified as
early dead (1-6 day), mid dead (7-12), late deed (13-18) and dead
during hatch (19-21 day). Hatchability of fertile eggs was
calculated.
A total number of 960 hatched chicks were randomly selected
(24 chicks of each group), wing banded, individually weighed,
vaccinated and kept under a similar and standard conditions of
management, environment, hygein and nutrition.
Each group was injected with the same level of hormone on
days 21 and 35 of age.
Body weight was weekly and individually recorded to the
nearst gram along the experimental period. Weight gain and rate of
growth between two successive periods were individually
calculated. Feed consumed by all chicks of each treatment was daily
recorded, averaged and expressed in grams per day per chick. Feed
conversion was then calculated as a ratio between feed intake (gm)
and weight gain (gm). Performance index was individually
calculated. Economical efficiency was also calculated and carcass
quality were measured at the 49th day of age.
Plasma thyroxine (T4) and triiodothyronine (T3) were
determined at day old, 28 and 49 days of age. Also, plasma calcium,
inorganic phosphorus and alkaline phosphatase were determined at
the 28th and 49th day of age.
Weights of the thyroid, adrenal and pituitary glands were
recorded and the thyroid was examined histologically.
Results obtained could be summarized as follows:
Highly significant effect on egg weight loss was found due to
incubation relative humidity (RR). Incubating eggs at 48% RH
resulted in an increased egg weight loss during the whole period of
incubation (O-18days). Injection time had significant effect on egg
weight loss at all experimental period. Eggs injected at the 9th day
of incubation significantly higher egg weight loss all over the
incubation period. Significant effects on egg weight loss were found
due to treatments applied at the period from (0-3) and (9-12) days
of incubation.