MPORTANT EVENTS IN EMBRYONIC DEVELOPMENT

BEFORE EGG LAYINGFertilizationDivision and growth of living cellsSegregation of cells into groups of special functionBETWEEN LAYING AND INCUBATIONNo growth; stage of inactive embryonic lifeDURING INCUBATIONFIRST DAY:16 hours - First sign of resemblance to a chick embryo18 hours - Appearance of alimentary tract20 hours - Appearance of vertebral column21 hours - Beginning of formation of nervous system22 hours - Beginning of formation of head23 hours - Appearance of blood islands - vitelline circulation24 hours - Beginning of formation of eyeSECOND DAY:23 hours - Beginning of formation of heart35 hours - Beginning of formation of ear42 hours - Heart begins to beatTHIRD DAY:50 hours - Beginning of formation of amnion60 hours - Beginning of formation of nose62 hours - Beginning of formation of legs64 hours - Beginning of formation of wings70 hours - Beginning of formation of allantoisFOURTH DAY:Beginning of formation of tongue

FIFTH DAY:Beginning of formation of reproductive organs and differentiation of sexSIXTH DAY:Beginning of formation of beak and eggtoothEIGHTH DAY:Beginning of formation of feathersTENTH DAY:Beginning of hardening of beakTHIRTEENTH DAY:Appearance of scales and clawsFOURTEENTH DAY:Embryo turns its head toward the blunt end of eggSIXTEENTH DAY:Scales, claws, and beak becoming firm and hornySEVENTEENTH DAY:Beak turns toward air cellNINETEENTH DAY:Yolk sac begins to enter body cavityTWENTIETH DAY:Yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cellTWENTY-FIRST DAY:Hatching of chick

air cell - a space at the large end of the egg, between the inner and outer shell membranes. albumin - the egg white. It provides protein and water for the embryo and protects it from microorganisms. allantois - a sack that holds some of the embryo's waste. It is attached to the embryo near the legs. amnion - a membrane that surrounds the embryo, protecting it from dehydration (losing water) and shock. eggshell - the hard, protective coating of the egg. It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg. It is made of calcium carbonate. embryo - the developing chick inside the egg. eye - large and prominent on the head. inner shell membrane - the thin membrane located between the outer shell membrane and the albumin. leg - one of the lower limbs of the chick. outer shell membrane - the thin membrane located just inside the shell. tail - located at the far end (the posterior) of the embryo. wing - one of the upper limbs of the chick. yolk - the yellow part of the egg; it contains nourishment (food) for the embryo

Egg propertiesEgg properties

• Std Weight- 58g• Specific Gravity   1.09• Weight %• Shell 10.5• Yolk 31• White 58.5• Total Edible      89.5

• Std Weight- 58g• Specific Gravity   1.09• Weight %• Shell 10.5• Yolk 31• White 58.5• Total Edible      89.5

Egg content Edible(  %)Egg content Edible(  %)

• Protein 12.0• Fat 11.3• Carbohydrate 1.0• Water 74.5

WHOLE EGGWHOLE EGG

• Water 73.7%• Protein 14.8%• Fat 10.5%• Ash  1%

• Water 73.7%• Protein 14.8%• Fat 10.5%• Ash  1%

CholesterolCholesterol

• Per egg  -213-250 mg

• Per 100g Liquid Egg  -425mg

YOLKYOLK

• Water 48%• Protein 17.5%• Fat 32.5%• Ash 2%

• Water 48%• Protein 17.5%• Fat 32.5%• Ash 2%

The composition (by weight) of the most prevalent fatty acids in egg yolk is typically as follows:Unsaturated fatty acids:

Oleic acid 47 %Linoleic acid 16 %Palmitoleic acid 5 %Linolenic acid 2 %

Saturated fatty acids:Palmitic acid 23 %Stearic acid 4 %Myristic acid 1 %

Egg yolk is a source of lecithin, an emulsifier and surfactant.The yellow color is caused by lutein and zeaxanthin, which are yellow or orange carotenoidsknown as xanthophylls

The composition (by weight) of the most prevalent fatty acids in egg yolk is typically as follows:Unsaturated fatty acids:

Oleic acid 47 %Linoleic acid 16 %Palmitoleic acid 5 %Linolenic acid 2 %

Saturated fatty acids:Palmitic acid 23 %Stearic acid 4 %Myristic acid 1 %

Egg yolk is a source of lecithin, an emulsifier and surfactant.The yellow color is caused by lutein and zeaxanthin, which are yellow or orange carotenoidsknown as xanthophylls

EGG white composition  in %EGG white composition  in %

• Water 88• Protein 11• Fat  0.2•  Ash 0.8

• Water 88• Protein 11• Fat  0.2•  Ash 0.8

Egg yolk composition

• Water    48%• Protein 17.5 %• Fat 32.5%• Ash 2.0%

ShellShell

• Percentage of egg weight-  9-12• Cal carbonate 94%• Magnesium Carbonate 1%• Cal Phosphate 1%• Organic matter 1%

Egg production of poultryEgg production of poultrySpecies Age at sexual

maturityEggs per year (no) Egg size(g)

Chicken- egg type 5-6  months 240 50-58

Meat type 5-6 months 150-170 55-58

Turkey 7 months 105 85

Goose 24 15-60 150-200

Duck  7-8 110-175 80

Quail 6 weeks 200-240 10-12

Guinea Fowl 10-12 40-60 40

NUTRITIVE VALUE OF EGGSNUTRITIVE VALUE OF EGGSDAILYVITD INTAKE RECOMMEVITB2NDED

1 EGG

ENERGY ( CAL) 3000RIBOFLAVIN 90

PROTEIN (g) 70 6.6

FAT(g) 50 5.5

CARBOHYDRATE (g) 570

CALCIUM 0.8 0.03

PHOSPHORUS 0.9 0.12

IRON 12 1.6

VIT-A 5000 600

VIT-D 400 50

VIT-B2 (mg) 1.5 0.095

VIT-C( mg) 75

RIBOFLAVIN (mg) 2.0 0.19

NICOTINIC ACID (MG) 18 0.04

Table 12.15. egg composition of various species(without sheil, per 100 (g) basis)Species H2O Protein Liplds Carbohy drates Ash Energy*

(g) (g) (g) (g) (g) (g) kcal)Chicken 73.7 12.9 11.5 0.9 1.0 163Duck 70.4 133 145 0.7 1. 1 191cook 70.4 I; 9 13.3 1.5 1. 1 185Guinea 72.8 135 12.0 0.8 0. 9 170Pigeon 728 13.8 12.0 0.8 0. 9 170Quails 73.7 13.1 11.1 1.0 1. 1 161Turkey 726 131 11.8 1.7 0. 8 170Kcal/OO g edible egg=g proteinx4 63+g lipids ' 9.02 +

carbohydrate X 3.87.

JUDGING FOR POOR PRODUCTION IN CHICKEN

Character Laying hen Non-laying hen

1. Comb Large, red, full, glossy, warm Small, pale, scaly, cold2. Wattles and ear Prominent, soft, Inconspicuous,rough, dry lobes smooth3. Vent Large, dilated, oblong, moist Small,contracted,round,dry4. Pubic bones Wide apart (usually about 3 Close together (One or

fingers) two fingers)5. Abdominal A depth of 4-5 fingers from A depth of 2-3 fingers only cavity the end of the keel to the

pubic bones6. Handling quality a. Soft and pliable abdomen a. Abdomen not flexible

and rubbery b. Pubic bones thin, pliable b. Rigid c. Low subcutaneous fat c. High

DISTANCE BETWEEN PUBIC BONES AND KEEL OF A GOOD LAYER (A AND a) AND A BAD LAYER (B 

AND b).

FIG. 12.6.

RELATIONSHIP BETWEEN DEPIGMENTATION OF BODY PARTS AND NUMBER OF EGGS LAID

•  

• Order of No. of eggs laid to Time taken to bleach• depigmentation bleach the body part (after first egg is laid)• Vent 0 to   10 eggs 0 to   2 weeks• Eye ring and ear lobe 10 to   15 eggs 2 to   3 weeks• Beak 35 eggs 6 to   8 weeks• Shanks:•       Bottom of feet 68 eggs 12 to 16 

weeks•       Front of shank 96 eggs 16 to 24 

weeks• Entire shank 175 eggs 24 to 32 weeks

Production indices

• • These serve as efficiency measures in a layer farm•  • 1• Feed efficiency/kg. egg mass    =  Kilograms of feed consumed•                                                       Kilogram of eggs produced• 2• Feed efficiency/dozen eggs     =   Kilograms of feed consumed •                     Dozen eggs produced• 3• Hen-Housed egg production = Total number of eggs produced on that day x 100•           ( one day)                          Total number of hens housed at the beginning•  • ]•

4

 Hen-Housed egg production= Average daily number of eggs produced x 100

         (longer period) Total number of birds housed at the beginning5% Hen-day egg production = Number of eggs produced on that day x100 ( one day) Total number of live hens on that day 6% Hen-day egg production ( longer period ) =  Total number of eggs produced during a period of time x 100 Total number of hen days [opening balance (OB)of hens on all these days