Topic 64 - Basal- and resting energy metabolism, factors affecting metabolic rate

Question 1

Words to include in basal- and resting energy metabolism

Answer 1

• Basal Metabolic Rate (BMR)
  
  • Complete rest
  • Ø muscular activity
  • Ø physical excitement
  • Neural environmental temperature
  • 12-14 hours fasting
  • Ø animals
• Resting metabolic Rate (RMR)
  
  • Before morning feed
  • Standstill, lying or resting
• Metabolic spectrum
  
  • Heat turnover
  • Depends on activity

Question 2

Words to include in factors affecting metabolic rate

Answer 2

• Body size
  
  • Large mass animals produce more heat than small mass animals
• Body surface
  
  • Logarhitmic relation
• Neural and hormonal effects
  
  • Epinephrine, norepinephrine
    
    • Glycogenesis
    • Brown adipose tissue
  • Growth hormone
  • Thyroid hormone
    
    • Increased secretion → higher MR
    • Decreased secretion → lower MR
• Specific dynamic action
  
  • 1-3 hours after food intake, BMR increases
  • Metabolizabel energy decreased by:
    
    • Digestive work (20%)
    • Absorption and storage activity (20%)
    • Desamination of amino acids (60%)
  • Proteins (30%)
  • Carbohydrate (5-7%)
  • Lipids (5-10%)
  • VFA (20-25% -ruminants)
• Temperature
  
  • Body temperature
    
    • Internal temperature
    • Changing velocity of chemical reactions
      
      • Excessive muscular work
      • Fever
  • Environmental temperature
    
    • ​Under lower critical / over higher critical temperature → metabolism ↑
    • Acclimatization mechanisms of thyroid hormones
• Muscle work (activity)
  
  • Metabolism ↑
  • Large animals: higher metabolism at initiation of movement
  • Small animals: higher metabolism during maintenance
• Production
  
  • Higher energy, above RMR

Question 3

Topics to include in the essay

Answer 3

1. Basal- and resting energy metabolism
   
   • BMR
   • RMR
   • Difference between BMR and RMR
   • Metabolic spectrum
2. Factors affecting metabolic rate

Question 4

Basal- and resting energy metabolism

Answer 4

Basal Metabolic Rate (BMR)

• The number of calories required to keep your body functioning at rest
• Complete rest, no muscular activity
  
  • Lying posture
  • Absence of any physical excitement
  • Neutral environmental temperature
  • 12-14 hour fasting
  • No heavy physical activity before the measurement
• Not possible to measure in animals

Resting Metabolic Rate (RMR)

• Conducted before the morning feed
  
  • In natural or experimental conditions
  • Animal is at a standstill, lying or resting
• Possible to measure in animals

Difference between BMR and RMR

• Specific dynamic action
• The amount of energy necessary for production (eg. Milk, egg)
• The amount of energy, which is needed by the animal above the energy used for real vital processes during measuring of energy in resting state
  
  • Components:
    
    • Specific dynamic action
    • Continous utlization of energy

Metabolic spectrum

• Heat turnover
• Takes place BMR (or RMR)
• Depends on the activity of the animal

Question 5

Factors affecting metabolic rate

Answer 5

• Body size
  
  • ​Animals of larger mass produces more heat than animals of smaller mass
  • Mouse-elephant curve
• Body surface
  
  • ​There is a logarithmic relation between metabolism and size of body surface among different species
    
    • Protozoa
    • Poikotheric animals
    • Homeotheric animals
• Neural and hormonal effects
  
  • Epinephrine, norepinephrine
    
    • ​Direct action on glycogenesis and brown adipose tissue
  • Growth hormone
    
    • ​Direct stimulation can increase MR by 15 – 20%
  • Thyroid hormone
    
    • ​Increased secretion → higher MR and vice versa
• Specific dynamic action
  
  • ​Following food intake → BMR increase (2-3 hours)
    
    • Protein: 30%
    • Carbohydrates: 5-7%
    • Lipid: 5-10%
    • VFA: 20-25% (ruminants)
  • Metabolizable energy is decreased by:
    
    • Digestive work (20%)
    • Absorption and storage activity (20%)
    • Desamination of amino acids (60%)
• Temperature
  
  • ​Body temperature / internal temperature
    
    • ​Alter metabolism mainly by changing velocity of chemical reactions
      
      • ​Due to either:
        
        • Excessive muscular work
        • Fever
  • Environmental temperature
    
    • ​Underlower critical / over higher critical temperatureincreases metabolism
    • Persistent changes in environmental temperature – acclimatization mechanisms of thyroid hormones
• Muscular work (activity)
  
  • Metabolism ↑
  • Large animals: higher metabolism at initiation of movement than maintainance
  • Small animals: higher metabolism during maintainance than the larger animals
• Production
  
  • ​Requires higher energy, above RMR, depends on type of product
  • Meat higher than milk and eggs