الفهرس 
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Abstract
The present study was carried out at the Poultry Research Farm
belonging to Department of Animal Production, Faculty of Agriculture,
Zagazig University, Benha Branch.
It was aimed to improve the productivity of the laying hens during the
second productive year by inducing moult using the most common methods
of moult induction then treating force moulted hens with either Estradiol 17
f),Indomethacin (as antiprostaglandin) and Bromocriptine (as antiprolactine)
or Human chorionic gonadotrpohin (ReG) to accelerate the onset of laying
after moult and attain relatively higher productive rate.
Two hundred and seventy Hy-line laying hens aged 60 weeks were
randomly chosen from a large commercial flock. All selected hens were
approximately of an equal body weight and similar performance. Birds were
leg banded, housed in floor pens in a condensity of 5 hen/square meter. All
birds were reared under the same managerial, hygienic condition and fed the
same ration. Experimental birds were divided into three groups. Birds of the
first group fed ad libitum, unmoulted and considered as controls. The
second group of birds were force moulted by adding 1% zinc oxide on diet
for 14 days. While those of the third group were force moulted by feed
restriction (25%) for 7 days then fasting for 7 days. Birds of both the second
and third groups were equally divided after moulting into 4 subgroups
injected by the following materials. Distilled water (l st subgroup), Estradiol
17 13 (2nd subgroup), Indome1hacin and Bromocriptine (3rd subgroup),
Hwnan chorionic Gonadotropbine HCG (4th subgroup) .
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Body weight, feed consumption and conversion were recorded. Rate
of egg production, egg weight and egg mass were recorded as traits of egg
production.
Absolute and proportional weights of various egg components as well
as traits of egg quality were also estimated.
Blood samples for chemical analysis were collected from wing vein
at the start of the experiment and then at bi-weekly intervals up to the end of
the experimental period. Plasma total protein, albumen, globulen, total
lipids, cholesterol, calcium, phosphorus and alkaline phosphatase were
estimated at each intervals. While plasma estrogen, progesterone, T3, T4,
levels and T3ff4 ratio were measured before and during moult and at 4, 8
and 12 weeks after moult.
Results obtained could be summarized as follows:
l.Body weight significantly decreased during moulting in birds of all
experimental groups. Zinc oxide and fasting force moulted hens lost
about 10% and 21% of their initial body weight, respectively.
Higher body weight increase was observed in birds treated with
estradiol 1713 and those treated with Indo+bromo when compared with
other treated with HeG or distilled water.
Highly significant variation in body weight average was found due
to experimental intervals.
2.Non moulted hens (controis) conswnedmore feed (137 gmlhenlday) than
either zinc oxide (124 gmlhenlday) or fasting (121 gmlhenlday) force
moulted hens.
Hens treated with estradiol 1713bad significantly (p<O.OOI) lower
average of feed consmnption (117 gmlhenlday). On the other hand, hen
treated with (indo+bromo) had the highest average of feed consumption.