Animal Genetics and Breeding- ICAR JRF/SRF 2024

• Classification of Domestic Poultry:
• Mediterranean Class: Includes Single Comb White Leghorn, Minorca, and Ancona. Characterized by small body size, light weight, yellow skin, white earlobes, non-broodiness, and high feed efficiency, laying the largest number of white-shelled eggs ($\gt 300\text{ eggs/year}$).
• American Class: Dual-purpose (Rhode Island Red, Plymouth Rock).
• English Class: Dual-purpose/meat (Australorp, Sussex, Orpington).
• Asiatic Class: Heavy meat/broiler ancestors (Brahma, Cochin, Langshan) with low egg production.
• nalysis:
• (Mediterranean): Correct.

Correct option: (1) Mediterranean

• Life Cycle Phases of a Commercial Layer:

• Brooding Period: 0 to 6 (or 8) weeks of age, requiring artificial heat.
• Rearing (Grower) Period: From end of brooding (6–8 weeks) up to the onset of sexual maturity / first egg (18–20 weeks). During this phase, pullets are fed grower diets with controlled lighting and feeding to achieve target body frame without excess adiposity.
• Laying Period: From sexual maturity ($\approx 20\text{ weeks}$) through peak lay to culling at 72–80 weeks.
  • nalysis:

• (Rearing): Correct term.

• Metabolizable Energy (ME) Requirements of Layers:
• White Leghorn commercial laying hens in tropical environments (BIS / NRC standards):
• Layer Phase I (Onset to Peak Lay): Formulated with $2600 - 2700\text{ kcal ME/kg}$ (standard BIS: $2700\text{ kcal/kg}$) with $18\%\text{ CP}$ and $3.5-4.0\%\text{ Calcium}$.
• Excess energy ($\gt 2850\text{ kcal/kg}$) leads to fatty liver hemorrhagic syndrome (FLHS) and reduced egg production.
• nalysis:
• (2700 ME): Correct standard layer energy content.

Correct option: (3) 2700 ME