ENERGETIC EVALUATION OF FEEDS

Question 1

What are the nutrients required for?

Answer 1

• For the synthesis of body tissues and animal products; - as sources of energy (for maintenance and production).

Question 2

Aims

Answer 2

to express 

• the energy requirements of animals and 
• the energy contents of their feeds by the same energy terms.

Question 3

energy terms:

Answer 3

Gross Energy (GE),
Digestible Energy (DE);
Metabolizable Energy (ME);
Net Energy for maintenance (NEm);
Net Energy for lactation (NEl);
 Net Energy for gain (NEg).

Question 4

FLOW DIAGRAM

Answer 4

GE (Gross Energy or BE: Brutto Energy)=combustion method 
- Faecal Energy loss =indigestible nutrients
DE (Digestible Energy) = says more about feed than GE;
- Urinary and Gaseous (rumen and gut) Energy Losses ME (Metabolizable Energy) = even more accurate  
- Heat Increment
NEm NEl NEg (Net Energy)
(m: maintenance; l: lactation; g: gain).

Question 5

Energy units of measure

Answer 5

Joule (J); 1 cal = 4.184 J;
1 000 J (103 J) = 1 kJ (kilo joule);
1 000 000 J (106 J) = 1000 kJ = 1 MJ (mega joule).
Energy Contents of Feeds: 
MJ/kg or MJ/kg DM; kJ/g or kJ/g DM; 
1 kJ/g = 1 MJ/kg; 
• Energy Requirements of animals 
Monogastric animals: MJ/kg of feed; 
Ruminants: MJ/day.

Question 6

q, i, k

Answer 6

metabolizability („q”)=   (ME/GE)*100 
feeding level („i”: intensity of feeding)= E Intake/E Needed for Maintenance    
Partial transformation factor („k”) =  (NE/ME)*100 = 70-80% (NEm)    = 60-70% NEl           = 30-50% NEg

Question 7

Principles (a, b, c) and practice (d, e) of a modern energy evaluation system

Answer 7

a) E requirement of animals & E content of their feeds must be expressed with the same type of E;
b) it should be additive (substitution of feeds by each other);
c) it should be exact (positive correlation between the feed E term used and animal production);
d) simplicity (determination or prediction of feed energy by simple methods or parameters);
e) practicability (easy use in the nutrition practice); ACCURACY vs. SIMPLICITY.

Question 8

Monogastric animals mammals

Answer 8

GE  
- Faecal Energy : faecal loss not too high
DE (MJ/kg)=accurate enough 
Swine, Horse, Rabbit
i.e. piglets need 40kJ/kg DE

Question 9

Monogastric animals Poultry

Answer 9

GE 
- Faecal Energy loss 
DE  
- Urinary and Gaseous Energy Losses 
ME (MJ/kg) =used as is more accurate

Poultry: AMEn (Apparent Metabolizable Energy corrected to zero N retention.)

Question 10

Monogastric animals others

Answer 10

Dogs Cats  Possibilities  DE, ME ME

Fur Bred Animals  Possibilities  Herbivorous (Nutria, Chinchilla) =DE Carnivorous (Polecat, Mink, Fox)= ME

Question 11

Ruminants- Dairy Cow: NEl (MJ/day)

Answer 11

GE 
- Faecal Energy loss 
DE  
- Urinary and Gaseous Energy Losses 
ME   
- Heat loss -very high in high producers
NEl -only parameter observed

Question 12

Beef Cattle, Dairy Heifers, Sheep

Answer 12

GE
- Faecal Energy loss 
DE 
- Urinary and Gaseous Energy Losses 
ME    
- Heat loss 
NEm,  NEg=> the 2 numbers are needed to characterise daily requirements

Question 13

Goat

Answer 13

Dairy or Meat Types  Possibilities  NEl (dairy) NEm+NEg.(meat)