Advanced Genetics

• 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

• Inbreeding Defined: Inbreeding is the mating of individuals that are more closely related to each other by ancestry than the average relationship of individuals within the reference population.
• Genetic Consequences of Inbreeding:
• Increases homozygous genotype frequency ($AA$ and $aa$) while decreasing heterozygosity ($Aa$) at a rate of $F$ (inbreeding coefficient).
• Exposes detrimental recessive alleles, leading to inbreeding depression (reduced fertility, viability, and production).
• Distinctions:
• Pure breeding: Mating of animals within the same established breed.
• Crossbreeding: Mating of animals from two or more distinct pure breeds.
• Outbreeding: Mating of unrelated individuals within a breed (outcrossing) or between breeds.

Correct option: (3) Inbreeding