Overview of Protein and Energy Systems

1
Overview of Protein and Energy Systems
2
Protein Utilization

• Monogastrics
• Dietary protein is unfolded (denatured) by
  stomach acid
• Enzymes bind to unfolded protein and begin
  cleaving into peptides and AA
• AA are absorbed and used as
• Protein (tissue) synthesis
• Energy source

3
Protein Utilization

• Monogastrics
• Understand the concept of limiting nutrient
• Animal will only perform to the level of the most
  limiting nutrient in the diet
• Must balance EAA to NEAA so AA are used for
  protein synthesis and not burned inefficiently
  for energy
• AA imbalance causes AA build-up in
  blooddecreases feed intake, decreases performance

4
Protein Utilization

• Monogastrics
• Recognize that diets are balanced on Limiting AA
  concept for the most part
• Assumption Meet Lysine reqt. then you will meet
  all EAA reqts.
• Recently, the use of the IDEAL AA concept has
  become popular
• No excesses or deficiencies of any AA
• Decreases N excretion and waste

5
Protein Utilization

• Monogastrics
• Recognize that the NRC expresses the pigs AA
  requirements on a TOTAL and DIGESTIBLE AA basis

6
Energy Utilization

• Monogastrics
• Swine Poultry use ME as their expression of
  energy
• ME GE FE UE Gaseous E
• Measure this by using bomb calorimetry on feed,
  feces, and urine
• Gaseous energy can be measured through indirect
  calorimetry

7
Protein Utilization

• Ruminants
• Rumen fermentation puts a twist on providing
  protein to the animal
• Microbial requirement (first access in rumen)
• Animal requirement (first access in SI)

8
Protein Utilization

• Ruminants
• Protein in feedstuffs divided into 2 categories
• DIP - Degradable Intake Protein
• Degraded in the rumen
• UIP - Undegradable Intake Protein
• Escape - Not degraded in the rumen
• usually called bypass or escape protein

9
Protein Utilization

• Ruminants
• Metabolizable Protein (MP)
• Amount of UIP and BCP that is digested/absorbed
  in the small intestine
• Accounts for protein digestibility (UIP and BCP)
  in small intestine AND the amount of bacterial
  protein synthesis (from DIP) in the rumen
• Accounts for USEABLE protein in a feedstuff/ration

10
Energy Utilization

• Ruminants
• The NE system takes into account heat lost
  through microbial fermentation, digestive
  processes nutrient metabolism
• Computed as ME HI
• HI plays a large role in ruminant metabolism
  because it mainly results from heat lost through
  fermentation of fibrous feedstuffs

11
Energy Utilization

• Ruminants
• Net energy is divided into 3 categories
• NEm, NEg, NEl
• Accounts for different efficiencies of energy
  utilization when in different stages of the
  lifecycle
• NEg reqt. will change depending on if growth is
  muscle or fat
• NEl reqt. will change based on milk fat, level of
  production, stage of lactation, etc.