Ovary of Hen

Ovary of Hen.

EGG STRUCTURE

EGG STRUCTURE Four Major structures of the egg from outside to inside are Shell membranes

EGG SHELL

EGG SHELL The egg shell consists of: Spongy or calcarious layer Egg Pores Average number of pores varies from 8,000-10000 per egg, distributed unevenly over the shell surface with more number of pores at the broad end than at the narrow end.

SHELL MEMBRANE

SHELL MEMBRANE The shell membrane consists of Outer shell membrane Inner shell membrane Air cell is situated in between the two membranes at the broad end.

The inner shell membrane closely surrounds the albumen.

The outer shell membrane is attached firmly to the shell by numerous cones on the shell surface extending into the membrane. The inner shell membrane closely surrounds the albumen.

The albumen consists of 4 layers, namely

The albumen consists of 4 layers, namely Chalaziferous or inner thick white, which forms (3%) Inner thin albumen (17%) Outer thick firm or dense albumen (57%) Outer thin albumen (23%) of total albumen

The yolk consists of

The yolk consists of Concentric layers of dark and light yolk material, due to differences in their chemical composition. Latebra is the centre of the yolk, which is a small, nearly circular core of light coloured fluid, which does not completely harden on boiling.

In an infertile egg it is unicellular (ovum) and contains haploid number of chromosomes, called "Blastodi

In an infertile egg it is unicellular (ovum) and contains haploid number of chromosomes, called "Blastodisc". It is circular in shape, with a diameter of about 3.5 mm and with vacuoles in it. Where as in a fertile egg, it is a multicellular structure having diploid number of chromosomes, called "Blastoderm". It is oval in shape, with an average diameter of about 4.5 mm and with no vacuoles in it.

"Vitelline membrane" is a semi-permeable elastic membrane, surrounding the yolk, separating the yolk material from the albumen.

FERTILITY AND HATCHABILITY

FERTILITY AND HATCHABILITY Fertility Refers to capacity to reproduce. It is the factor, which determines the successful offspring that may be obtained from a given number of eggs.

Factors influencing fertility

Factors influencing fertility Sex Ratio Age of breeders Length of duration between mating Diseases and management practices. Fertility is expressed as % of fertile eggs in a set of total eggs incubated. Fecundity-Producing many offspring. Fecundate – To fertilize

Hatchability

Hatchability Is defined in two ways Based on the fertile eggs set (FES) Based on the total eggs set (TES) Refers to the % of chicks hatched to the eggs set. Size, shape and condition of egg shell are important for hatching. Very large and very small eggs do not hatch well.

Eggs having abnormal shape show low heritability.

Eggs having abnormal shape show low heritability. Condition and duration of storage of eggs prior to incubation as well as setter and hatcher environment affect hatchability (or) The quality of fertilized egg to produce normal embryonic development with normal emergence of the young when incubated.

FACTORS AFFECTING FERTILITY

FACTORS AFFECTING FERTILITY Age of the parent stock: There is an increase in fertility in a breeder flock between the ages of 25 to 40 weeks after which fertility gradually diminishes Breed: Lighter breeds like White Leghorn is more fertile than heavier breeds like the broiler breeders. Genetic factors: Many genes influence fertility eg: in Wyandotte the gene responsible for rose comb (RR) lowers fertility in males.

Environmental factors: Excessive high and low temperature reduces fertility due to poor mating frequency

Environmental factors: Excessive high and low temperature reduces fertility due to poor mating frequency because of the inactiveness of the birds. Disease conditions: Many diseases like Ranikhet disease, Mycoplasmosis, Salmonella etc., affect fertility.

The semen volume, sperm concentration and number of successful mating also alter fertility.

Sex ratio: Both higher and lower males to female ratio will reduce fertility. The recommended ratio in lighter breeder is 1:10-12,. In broiler breeder 1:8-10 and in J.quails 1:1-2 The semen volume, sperm concentration and number of successful mating also alter fertility. Inseminating the birds during the after noon can lower fertility.

Male nutrition: Male breeders should be fed with lower protein levels of 12-14% for optimum fertility.

Nutritional factors: Some deficiencies like vitamin A, E , Biotin, Pantothenic acid and B2 and minerals like calcium, phosphorous, sodium, Magnesium, Manganese, Zinc and Iodine lower fertility. Photo period: A photo period of 16 hrs per day will give optimum fertility. By either lowering the length of period to 12 hrs or increasing it to 18 hours lowers the fertility.

Male nutrition: Male breeders should be fed with lower protein levels of 12-14% for optimum fertility.

Thanks for your attention

Thanks for your attention