AnSc 121 LESSON 7

EGG QUALITY ASSESSMENT

Status of Chicken Eggs in the Country

status report on April-June 2022

  • CALABARZON - top producer of chicken egg (34.2% share)

  • Central Luzon, Central Visayas, Northern Mindanao, Western Visayas

Egg Evaluation

The on-farm evaluation of egg quality has two main purposes:

  1. To review the status of a given farm or flock/barn

  2. To benchmark the quality of eggs against the offering of competitors.

Egg Structure

  • Shell - provides physical and biological protection from the environment and regulates the exchange of water and gases.

  • Cuticle - laid on the external surface of eggs, large portion of the superficial pigments.

  • Yolk - surrounded with vitelline membrane, contains (50% water, 30% lipids, 17% proteins). In addition, it is rich in fat-soluble vitamins (A, D , and E), minerals (Phosphorus), and carotenoids (gives the golden color of the yolk)

  • Albumen or egg white - thick/thin, chalaza/chalaza layer, consists water and proteins (10%)

  • Chalazae - attached to the thick albumen, anchors the yolk

Egg is made of three distinct parts:

  1. shell (10% of weight)

  2. albumen (60% weight)

  3. yolk (30% weight)

Egg Size

  • important dimensions: shape (oval) and weight (pullet, small, med, large, extra l, xxl)

Shell Quality

  • egg stained with blood- can occur on younger hens, result of a prolapse

  • color can be tinged with blue or green

  • shell color is a reflection of the breed, age, and health status

*Thickness and strength

  • shell form by the precipitation of calcium carbonate requires 2.3g of calcium

  • dietary provision of 25 (OH) D3 will allow a higher plasma level of metabolite, therefore better Ca absorption

  • used a micrometer to measure shell thickness

  • yolk index- the ratio of yolk height over yolk diameter, indicates egg’s freshness

  • yolk index: 0.38=extra fresh; 0.28-0.38 = fresh; <0.28 = regular

  • shell of 300-400 micrometers in thickness and can withstand a breaking force of at least 30 newtons

  • right balance of D3 and calcium will protect over time the integrity of the shell

Process of Egg Formation

  1. Ovary - mature ovum (ready to be ovulated)

  2. Infundibulum - site of fertilization

  3. Magnum - first layer of albumen, 3 hrs

  4. Isthmus - inner membrane, outer shell membrane, albumen added, 3 hrs

  5. Uterus - pigments added, 18 hrs

  6. Uterovaginal junction - location of the sperm, storage tubules

  7. Vagina

  8. Cloaca

Egg Freshness: Albumen

  • thick albumen, about 60% in freshly laid eggs

  • pH range from 5.6 to 7.5

  • when carbon dioxide dissipates, the pH rises to 9.5: affecting the structure of ovomucin (glycoprotein in thick albumen) which will make albumen lose its viscosity

  • Haugh unit (HU) - pH method determinant

Egg Freshness: Yolk evaluation (color)

  • carotenoids - responsible for yolk’s golden color

  • carotenoid is supplied by: yellow corn, corn gluten meal, lucerne, xanthophyll-rich ingredient flower (marigold), plant (paprika) extracts, or specialty ingredients like CAROPHYLL

  • color, intensity, shade, and homogeneity of the yolk are dependent on the rations fed to hens and their ability to properly absorb and deposit carotenoids.

  • Digital Yolkfan

Nutritive Value of Eggs

  • High-quality proteins, about 6g

  • several fat-soluble vitamins (vitamins A, D, and E)

  • water-soluble vitamins (vitamin B12, riboflavin, and folate)

  • micronutrients (Iodine, Iron, Phosphorus, and Selenium)