• Biosecurity Separation for Brooding Sheds:
• Because young day-old chicks possess immature immune systems and maternal antibodies decline rapidly, the brooding-cum-rearing shed must be isolated from adult layer/broiler sheds.
• The minimum recommended biosecurity buffer distance between the brooder house and other poultry sheds is $100\text{ feet}$ ($30\text{ meters}$), with separate dedicated attendants and equipment.

Correct option: (2) 100 ft

• Major Genes for Tropical Heat Tolerance in Poultry:

• Naked Neck Gene ($Na$): Reduces feather coverage by $30\%\text{ to }40\%$, improving convective heat loss from neck and body.
• Frizzle Gene ($F$): Curls feathers outwards away from the body, facilitating heat dissipation.
• Dwarf Gene ($dw$): Sex-linked dwarfism reducing metabolic heat production.
  • Fibromelanosis ($Fm$): Causes hyperpigmentation of dermal, connective, and visceral tissues (black meat/bones, e.g., in Kadaknath and Silkie chicken), but is not a heat tolerance gene.

• Discovery of Essential Amino Acids: Formulated by William C. Rose in the 1930s, who discovered the last essential amino acid, threonine (1935), and demonstrated the specific dietary requirement for 10 indispensable amino acids in animals.
• Other Concepts:
• Essential fatty acids: Burr and Burr (1929).
• Vitamins: Casimir Funk (1912).

Correct option: (4) Essential amino acids