Animals need proper nutrition for survival and thriving. A balanced diet provides essential nutrients for growth, repair, and optimal functioning of organs and systems. It prevents deficiencies, supports immunity, and maintains a healthy weight.

Key components of animal nutrition include macronutrients like carbs, proteins, and lipids, as well as micronutrients like vitamins and minerals. These nutrients are broken down through digestion and used for energy production in cells through processes like cellular respiration.

Nutrition and Energy Production in Animals

Balanced diet for animal health

• Balanced diet provides essential nutrients for:
  • Growth and development supports proper maturation of tissues and organs
  • Tissue repair and maintenance replaces damaged cells and maintains structural integrity
  • Proper functioning of organs and systems ensures optimal physiological processes (digestion, circulation, respiration)
• Prevents nutrient deficiencies and associated health problems (anemia, osteoporosis, immune dysfunction)
• Supports immune system function enhances resistance to infections and diseases
• Maintains healthy body weight and composition prevents obesity and related metabolic disorders (diabetes, cardiovascular disease)
• Contributes to overall homeostasis by providing necessary resources for bodily functions

Key components of animal nutrition

• Macronutrients
  • Carbohydrates: primary energy source for cellular processes (glucose)
  • Proteins: building blocks for tissues, enzymes, and hormones (amino acids)
  • Lipids: energy storage, cell membrane components, and signaling molecules (fatty acids, cholesterol)
• Micronutrients
  • Vitamins: essential for various metabolic processes (vitamin A for vision, vitamin C for collagen synthesis)
  • Minerals: required for proper physiological functions (calcium for bone health, iron for oxygen transport)
• Water: essential for hydration, transport, and biochemical reactions (solvent, temperature regulation)

Energy from diet through digestion

• Mechanical digestion: physical breakdown of food
  • Chewing and grinding in the mouth breaks food into smaller particles (teeth, tongue)
  • Churning and mixing in the stomach further reduces particle size (stomach muscles)
• Chemical digestion: enzymatic breakdown of macronutrients
  • Carbohydrates broken down into simple sugars (amylase, maltase)
  • Proteins broken down into amino acids (pepsin, trypsin)
  • Lipids broken down into fatty acids and glycerol (lipase)
• Absorption of nutrients in the small intestine
  • Villi and microvilli increase surface area for efficient absorption (brush border enzymes)
  • Nutrients transported into the bloodstream for distribution to cells (capillaries, lymphatic system)

Energy production in animal cells

• Cellular respiration: process of converting nutrients into usable energy (ATP)
  1. Glycolysis: breakdown of glucose in the cytoplasm produces pyruvate and ATP
  2. Citric acid cycle: oxidation of acetyl-CoA in the mitochondrial matrix generates NADH and FADH2
  3. Electron transport chain: generation of ATP through chemiosmosis transfers electrons from NADH and FADH2 to oxygen
• Oxidative phosphorylation: final stage of cellular respiration, producing most of the ATP
• Oxidation of fatty acids through beta-oxidation produces acetyl-CoA for citric acid cycle
• Catabolism of amino acids for energy production deamination and conversion to glucose or ketone bodies

Energy storage from carbohydrates

• Glycogen: primary short-term energy storage in animals
  • Stored in the liver and skeletal muscles (hepatocytes, myocytes)
  • Readily mobilized for energy during periods of fasting or increased energy demand (exercise)
• Adipose tissue: long-term energy storage
  • Excess carbohydrates converted to triglycerides and stored in adipocytes (lipogenesis)
  • Provides insulation and cushioning for organs (subcutaneous fat, visceral fat)
• Hormonal regulation of energy storage and mobilization
  • Insulin promotes glucose uptake and glycogen synthesis (anabolic hormone)
  • Glucagon stimulates glycogen breakdown and glucose release (catabolic hormone)

Metabolism and Bioenergetics

• Metabolism: sum of all chemical reactions in an organism
  • Anabolism: building complex molecules from simpler ones (requires energy)
  • Catabolism: breaking down complex molecules into simpler ones (releases energy)
• Bioenergetics: study of energy flow through living systems
• Fermentation: anaerobic process that produces energy in the absence of oxygen