• Metabolic Integration:
• Metabolism is defined as the sum total of all coordinated biochemical reactions and energy transformations occurring within a living organism to maintain cellular homeostasis, growth, and reproduction.
• It consists of two complementary branches:

• Catabolism: Exergonic, oxidative breakdown of complex macromolecules into simpler molecules, releasing usable metabolic energy (ATP).
• Anabolism: Endergonic synthesis of complex cellular constituents (proteins, lipids, nucleic acids) from simpler precursors, requiring ATP input.
  • nalysis:

• (Metabolism): Correct.

• Comparative Cost of Macronutrient Energy Sources:
• Carbohydrates: Sourced from grains, cereal by-products (rice bran, wheat flour, broken rice), and starch tubers. They represent the cheapest and most abundant source of dietary energy in commercial feed production.
• Lipids: Provide the highest caloric density but are significantly more expensive than carbohydrates.
• Proteins: Sourced from fishmeal, poultry meal, or processed oilseed meals; protein is the single most expensive macro-ingredient in aquafeeds. Using protein for energy (instead of sparing it with carbohydrates and lipids) is economically inefficient.
• nalysis:
• (Carbohydrate): Correct.

Correct option: (2) Carbohydrate

• Pigmentation in Decapod Crustaceans:
• Astaxanthin ($3,3'$-dihydroxy-$\beta,\beta$-carotene-$4,4'$-dione) is the predominant carotenoid pigment in penaeid shrimps (e.g., Penaeus monodon, Litopenaeus vannamei), lobsters, and crabs, accounting for $80-95\%$ of their total carotenoids.
• In live shrimps, astaxanthin is bound to proteins forming blue/green-colored crustacyanin complexes.
• Upon thermal processing (boiling/steaming), heat denatures the crustacyanin protein, liberating free uncomplexed astaxanthin which displays its characteristic bright orange-red hue.
• nalysis:
• (Astaxanthin): Correct.

Correct option: (3) Astaxanthin

• Least-Cost Feed Formulation:
• Linear Programming (LP) is an advanced mathematical optimization technique used by feed millers to calculate the exact proportion of each available feed ingredient required to produce a balanced diet at the lowest possible economic cost.
• It solves simultaneous linear equations and inequalities to satisfy multiple nutrient constraints (crude protein, digestible energy, individual essential amino acids, calcium, available phosphorus, fiber limits) while minimizing the objective cost function:

• nalysis:
• (Linear programming): Correct.
• (Pearson's square): Simple manual algebraic method limited to balancing two ingredients for a single nutrient constraint.

Correct option: (3) Linear programming