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Register a new userEgg Production of the Domestic Hen is a Reflection of Ovarian Physiology-A Review: Part ٣. Control of Follicular Growth and Maturation
إنتاج البيض في الدجاج الأليف هو انعكاس للفيزيولوجيا المبيضية دراسة مرجعية: الجزء الثالث. التحكم في النمو الجريبي المبيضي و نضجه
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Damascus University ورقة بحثية
Publication date
2002
fields
Animal Production
and research's language is
العربية
Authors
عبد الحميد زكريا( باحث )
Created by
Shamra Editor
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توجد أدلة عدة جديرة بالاعتبار تدعم دور موجهة الُقْند (الغونادوتروفينز) و هرمون البروجستيرون في نمو الجريبات المبيضية و نضجها و المحافظة على الوظيفة المبيضية في الدجاج. و من ناحية أخرى، تتوافر قائمة طويلة و متجددة من العوامل التي قد ترتبط بنمو الجريبات المبيضية و الإباضة منها في الوقت الحاضر منطقة القرص الإنتاشي، عوامل النمو المنشطة و المثبطة، البلعميات، محفز مولد البلزمين، البروستاغلاندينات، الببتيد المعوي القابض و تداخلاتها.
There is considerable evidence supporting the role of gonadotrophins and progesterone on follicular growth and maturation and functional maintenance of the ovary in the hen. Recently, however, there are ever-expanding list of factors may be involved in establishing follicular growth and ovulation currently including germinal disc region, growth factors, macrophages, plasminogen activator, ornithine decarboxylase, inhibin, activin, follistatin, relaxine, arginin vasotosin, oxytocin, prostaglandines, vasoactive intestinal peptide, and their interactions.
References used
Bahr, J. M., L. K. Ritzhaupt, S. McCullough, L. A. Arbogast, and N. Ben- Jonathan, ١٩٨٦. Catecholamine content of the preovulatory follicles of the domestic hen. Biol. Reprod
Bahr, J. M., and S. S. Palmer, ١٩٨٩. The influence of aging on ovarian function. Crit. Rev. Poult. Biol
Bahr, J. M., and P. A. Johnson, ١٩٩١. Reproduction in Poultry. PP ٥٥٥-٥٧٥. in: ‘Reproduction in Domestic Animals.’ P. T. Cupps Edn. (Academic Press, New York
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The ovary of a laying hen contains follicles in the rapid growth phase
which have advanced from a pool of follicles in the resting stage of about
٦-٨ mm in diameter. Little is known about mechanisms regulating follicular
transformation from the re
sting stage to the rapid growth phase. One potential
regulator of this transformation may be Follicle Stimulating Hormone
(FSH). In addition, there are accumulating results indicating that a negative
relationship between inhibin and FSH may be existed.
Three experiments were conducted using Cobb 500 broiler breeders to determine oviposition pattern and the effect of oviposition time of eggs representing different positions in the normal egg laying sequence on egg weight , fertility , hatchability , embryonic mortality and chicken weight at hatch.
Twelve growing Shami heifers available in Dier-Al-Hajar Station for
improving Shami Cattle weighing 115±3 kg and 178±4 days old were used to
monitor the daily growth of ovarian follicles (daily numbers, size, length and
number of waves, rate of gr
owth and regression) using Transrectal Ultrasound
Echo System (7.5 MHz probe) in 6-14 months-old heifers. Results indicated that
ovarian follicles developed in a wave pattern in all Shami heifers when they
were 6 months old and no significant differences in the number and size of
ovarian follicles were found between right and left ovaries. A cohort of 4 to 7
small follicles with a diameter 2-5 mm developed together and one of them was
selected for continual growth, became dominant and later regressed during the
pre-pubertal stage.
Twelve growing Shami heifers available in Dier-Al-Hajar Station for
improving Shami Cattle during 2005-2007 weighing 250±11 kg and 400±21
days old were used to monitore the growth of dynamic of ovarian follicles (daily
numbers, size, length and nu
mber of waves, rate of growth and regression) and
characteristics of estrus cycle (length, time of dominancy, diameter of Graffian
follicle and estrus and ovulatory times), length of corpus luteum (CL) during
the estrous cycle. Heifers were maintained under uniform conditions and fed
according to their daily growth. Transrectal Ultrasound Echo System (7.5 MHz
probe) was used to study the ovarian structures and to monitor the daily
development and regression of ovarian follicles, the formation and regression of
corpus luteum in the left and right ovaries during the estrus cycle. Results
indicated that the growth turnover of ovarian follicles was observed and
developed in a wave pattern in all Shami heifers and no significant differences
in the number and sizes of ovarian follicles were found between right and left
ovaries. A cohort of 5 to 7 small follicles with a diameter 2-5 mm developed
together and one of them was selected to continue growing and becomes
dominant and later on being regressed or ovulated during the estrus cycle. One
to five follicular waves were observed per cycle and each wave was
characterized by the development of one large (dominant) follicle and a
variable number of smaller follicles. The estrus cycle with one follicular wave
occurred only in heifers exhibited the first post pubertal cycles with an average
length equaled to 8.67±0.33 days. Frequency of estrus cycle according to the
number of follicular waves was 8.4, 25.3, 44.2, 20 and 2.1% in cycles having 1,
2, 3, 4 and 5 follicular waves, respectively. Furthermore , the length of estrus
cycle was also related to the number of follicular waves and it was 21.87±0.62,
22.44±0.74, 26.4±0.72, 26.50±3.50 days in cycles having 2, 3, 4 and 5 follicular
waves, respectively with significant differences (P < 0.05) in cycles with 2 or 3
vs. 4 and/or 5 waves. The functional duration of CL was extended to 9, 12 and
15 days in a short (17-19 days), intermediate (20-24 days) and long estrus cycle
(≥ 25 days). The maximum diameter of dominant follicles in ovulatory waves
was significantly larger (P < 0.05) than that of dominant follicles in nonovulatory
waves. In conclusion, this study showed that the development of
ovarian follicles in Shami heifers occurs in waves and the most common pattern
is three waves per estrous cycle.
Two experiments were carried out to determine the effect of flock
age on egg laying pattern, floor laying, egg weight, hatchability,
fertility and body weight at hatch. Eggs were collected from 32and
43 wk old Cobb 500 broiler flocks for 6 consecu
tive days hourly to
study egg laying pattern and floor laying (experiment 1). In
experiment 2, 2916 eggs from the flock at 32 ,43 and 49 wk old
were used to determine the effect of flock age on egg weight,
hatchability, fertility and body weight at hatch.
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