Energy partitioning

Question 1

`Why is energy needed

Answer 1

-for basic functionings of the animal body
- for any growth or production

Question 2

Where does a starving animal get energy from

Answer 2

catabolism of body reserves

Question 3

Where does a fed animal get energy from

Answer 3

by feed – prevent catabolism of body reserves

Question 4

why is it that not all GE is available to animal

Answer 4

• Energy lost through solid, liquid and gas excretions
• Energy also lost through heat

Question 5

Factors influencing ME

Answer 5

1. Digestibility of feed
   - ME is determined by DE
   - The degree to which the feed is digested affects the amount of energy available to the animal.
   - Diets with higher digestibility result in less energy lost through feces or undigested feed.

2.Type of fermentative processes
- extent of methane production in the rumen during fermentation
- Diets higher in fiber tend to produce more CH4.
- he same feed may have a higher ME value for monogastric animals compared to ruminants, as less energy is lost through urine and CH4.

3. Level of feeding and feed processing
   - lower DMI leads to longer retention time in GIT and increases digestion , resulting in a higher ME value of feed
   - higher DMI increases the passage rate, reduces digestion, and may lead to increased fecal energy loss, lowering the ME value of the feed.

Question 6

Three sources of HI

Answer 6

• Eating activity require muscular activity
• Rumen microbes generate heat
• Metabolism of nutrients also uses energy

Question 7

What is NE used for

Answer 7

1. Maintenance (NEm) – Used by body, leaves as heat
2. Production (NEl or NEg) – Stored in body or leaves as chemical energy

Question 8

Where does Heat loss from NE come from?

Answer 8

• Heat increment of feed degradation and digestion
• Heat increment from energy utilized for maintenance

Question 9

what is the relationship between ME intake and energy retention?

Answer 9

• the slope of line = measure of efficiency
• energy retention at 0 is indicative of ME intake sufficient to meet maintenance requirements
• once energy retention occurs (above maintenance ) the efficiency with which energy ME is used decreases as the cost of production is more than maintenance , more heat is lost relative to retention .
• The more energy retention, the better ME is utilised, less energy lost through heat increment
• Above maintenance, slope of line decreases, showing decreased efficiency

Question 10

Efficiency is highly variable, depends on:

Answer 10

1.Heat of fermentation
- Accounts for low calorimetric efficiency in ruminants in comparison to monogastrics

2. Function for which ME is designated
   - Maintenance is an energy efficient process
   - Growth is an energy expensive process
   - Lactation is more energy efficient than growth

km >kl > kg