Egg formation process in chicken

Egg formation process in hen is disussed. Egg fertilization also briefly discussed.

1. EggFormationProcessin
Chicken
Muhammad Arslan Musa
M.Sc. (Hons.) Poultry Science
[email protected]
Muhammad Arslan Musa

2. Chicken Egg
•Semi-solid nutritional mass enclosed in hard calcareous shell produced by female of
bird
•Chicken egg contain 8000-10000 pores in shell
•Hen requires 2-2.5 gram Ca for normal egg shell formation
Muhammad Arslan Musa

3. Egg Formation
Ovary = yolk formation
Oviduct = Albumin, shell membrane and shell
•Mature hen have 3600-4200 ova
•Egg formation requires 23-26 hours
Muhammad Arslan Musa

4. •Yolk matured in 10 day
•Ovulation take place 15-75 minutes after oviposition
•The earlobe color of hen can be an indication of eggshell color with some exceptions
Muhammad Arslan Musa

5. Hormones during Egg Formation
FSH = Activate ovary and oviduct
LH = Release ova from ovary (Ovulation)
Progesterone = release LH from pituitary
Arginine Vasotocin= Uterine contraction (oviposition)
Testosterone= comb growth, albumin formation
Estrogen= plumage growth, mating and nesting behavior, oviduct development, nutrient supply to
ovary and oviduct
Muhammad Arslan Musa

6. Reproductive Tract
•Reproductive tract = ovary + oviduct
•In Chicken, only left side remains functional
•Right ovary and oviduct regressed during embryonic growth
•MullerianInhibiting Substance (MIS) is responsible for regression
•Right one is functional in Hawk while both sides functional in Brown Kiwi
Muhammad Arslan Musa

7. Ovary
•Smooth before laying and later looks granular
•Looks like cluster of grapes before laying
•Left ovary present near proximity to left kidney
•During incubation, approximately 20,000 ova present in hen
•Mature hen have 3600-4200 ova
•Ovary size is 40-50 g in laying hen and 3-5 grams in broody hen
Muhammad Arslan Musa

8. Oviduct (Fallopian tubes)
Part of Oviduct Time (hours)
1 Infundibulam 15 minutess
2 Magnum 3
3 Isthmus 1.15
4 Uterus 20-21
5 Vagina Few minutes
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10. Medullary Bone Formation
•Soft and spongy bones inside long bones
•Calcium store for layer
•High estrogen level in blood initiate its formation
•Only present in females of chicken
•Highly important during night for egg formation in absence of feed
Muhammad Arslan Musa

11. Role of Light
•Photoreceptors are present in hypothalamus
•Photoreceptors perceive light and hypothalamus release GnRH
•GnRHact on pituitary to release FSH
•Specific light duration and intensity is required
•16-17 hours light with 0.75 fc intensity
Muhammad Arslan Musa

12. Initiation of Egg Formation
•11 days before first egg, anterior pituitary release FSH
•FSH activate ovary and oviduct
•Active ovary produced estrogen, progesterone and testosterone
•Hormonal + Nervous system is responsible for first ovulation
•Second ovulation regulated by first oviposition
Muhammad Arslan Musa

13. Estrogen
•Enlargement and Redding of comb and wattles
•Medullary bone formation initiates
•Stimulate yolk formation in liver
•Widening of pubic bones
•Prenuptial Feather Molt (Feather Drop)
•Enable oviduct to secrete its secretions
Muhammad Arslan Musa

14. Release of Ova into the Oviduct
•When ova get matured, progesterone hormone is released by ovary
•Progesterone stimulates hypothalamus to release LH from anterior pituitary
•LHcause rupture of follicle from stigma (suture line) and ovulation takes place
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15. Infundibulum (Funnel)
•Approx. 9 cm funnel-like structure
•Capture ova from ovary
•Sperms from males are temporarily stored here for fertilization
•Fertilization takes place if sperms are present
•Ova remains 15 minute here
•Only becomes active just after ovulation
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16. Egg Fertilization
•Cock mate 10-30 times a day with hen
•Semen ejaculation is 1 ml for first mating and then reduced to 0.5 ml or less
•100 million to 5 billion sperms are ejaculated per mating
•Sperms are stored in utero-vaginal junction
•Fertile eggs can be produced for 4 weeks after removal of males
Muhammad Arslan Musa

17. •Movement of sperm from this junction to infundibulum
- 30 minutes in absence of ovulation
- 5-10 minutes after an ovulation
•50 sperms penetrate outer layer of ovum (less than 30 leads to poor fertility)
•Few sperms move to germinal disk
•1 sperm unite with female pronucleusto form zygote
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19. Magnum
•Largest part of oviduct (33 cm long)
•Major portion of albumin secreted here
•Chalazae also secreted here
•All 4 layers of albumin produced and completed except outer thin white
•Developing remains here for 2-3 hours
•Only one type of albumin secreted in magnum but addition of water and rotation of egg make layers
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20. Isthmus
•Small length of 10 cm
•Less developed than magnum
•Ova remains here for 75 minutes
•Inner and outer shell membranes secreted here
•Outer membrane is about 3 times thicker than inner
•Eggs from young birds have thicker shell membranes than from old birds
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21. Uterus (Shell gland)
•10-12 cm long in laying birds
•Egg remains here for 18-20 hours
•Fourth layer of albumin (outer thin layer) is completed here by addition of water and
salts
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22. •Approximately 15 ml fluid is added by plumping process
•Egg shell, its pigment and cuticle is added here
•2-2.5 g calcium is used for shell formation from which53% taken from feed and 47 % from
bones
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23. Vagina
•Last part of oviduct and12 cm long
•Egg remain for few minutes here
•No egg formation occurs here
•Only expel the eggs outside the body
•Sperm store glands are present at junction of shell gland & vagina
•It can store sperms for 10-14 days
Muhammad Arslan Musa

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25. Oviposition
•Egg laying process is called oviposition
•Arginine Vasotocinfrom anterior pituitary control shell gland contraction
during oviposition
•Broader end comes first in the environment
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26. •Initially egg has smaller end outward
•Just before oviposition hen rotates egg in horizontal position and broader end comes first
from body
•Rotation takes about 2 minutes
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27. Air Cell Formation
•Air cell (0.7 inches) formed between inner and outer shell membrane at broader end
•Egg inside hen has no air cell
•When egg is laid its contents are contracted due to temperature difference
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28. •As the egg contents contracted, air cell is formed
•Broader end comes first so normally it formed at broader end
•As egg get older, moisture contents evaporated from eggs, air cell size increased
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29. Egg after Laying
•Freshly egg has temperature of about 104 0F
•Egg takes 4-6 hours to attain room temperature
•Air cell formed after egg laying
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30. Abbreviations
FSH = Follicle stimulating hormone
LH= Luteinizing hormone
GnRH= Gonadotrophic releasing hormone
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