Energy Part I

Question 1

% TDN equation

Answer 1

{(digestible protein + fiber +nitrogen free extract) + (fat X 2.25)} / (feed consumed)
X100

Question 2

Steps in determining TDN values

Answer 2

-digestibility
-computation of digestible nutrients
-computation of total digestible nutrients
%TDN = %DCP + %DCF + %DNFE + (%DEE X 2.25)

Question 3

Nitrogen-Free-Extract % equation

Answer 3

%NFE = %DM - (%EE + %CP + %ash + %CP)

Question 4

NFE accuracy

Answer 4

• very innacurate
• it is not an extract
• fraction has nothing to do with nitrogen
• accumulates all the errors that exist in proximate analysis

Question 5

TDN system advantage

Answer 5

it has been used for a long time and many people are familiar with the system

Question 6

TDN system disadvantages

Answer 6

• TDN is a misnomer (not actual total)
• does not include digestible mineral matter
• digestible fat is multiplied by a factor of 2.25; feed high in fat, could have TDN values exceeding 100%
• considers only digestive losses (not urine, gas and heat production)
• based on chemical determinations, not actual metabolism of the animal

Question 7

how to determine the starch equivalent

Answer 7

divide the energy value of feed by the energy value of starch

Question 8

Calorie
1 calorie = ?
1000 calories = ? = ?

Answer 8

unit of heat used to describe the energy yielding capability of foods on complete combustion
1 calorie = 4.184 joules
1000 calories = 1C = 1 kcal

Question 9

Gross Energy (GE)

Answer 9

the heat generated when a unit of mass of feed is completely combusted in oxygen to yield water and carbon dioxide under std conditions

• includes all the energy in the feed
• it is not available to the animal

Question 10

Digestible Energy (DE)

Answer 10

the gross energy of the feed consumed minus the gross energy of the feces
***are of no use to avian species!!!

Question 11

Fecal Energy (FE)

Answer 11

• energy of undigested dietary nutrients

- energy of endogenous secretions

Question 12

Metabolizable Energy (ME)

Answer 12

the feed intake gross energy minus fecal energy, minus urinary energy, minus gaseous products
**most common methods used in poultry!!

Question 13

Net Energy (NE)

Answer 13

the difference between metabolizable energy and the heat increment and includes the amount of energy used for maintenance only (NEm) or maintenance plus production (NEm+p)

• *NE = ME - HI
• very accurate
• difficult to determine

Question 14

Heat Increment (HI)

Answer 14

composed of the heat released through ingestion, digestion, and metabolism
-the act of eating (chewing, swallowing, metabolism, secretion) costs about 3-5% ME intake

Question 15

Gross Energy equation

Answer 15

(C6H12O6) + 6(O2) —–> 6(CO2) + 6(H20) + energy

Question 16

Poultry Energy Partitioning

Answer 16

true digestible energy is difficult to measure

-convenient to determine *****metabolizable energy of a diet by pooling excreta as a single material

Question 17

Swine Energy Partitioning

Answer 17

• ***DE system preferred
• gas from pigs is insignificant
• ME = 0.96 DE

Question 18

Ruminant Energy Partitioning

Answer 18

ME system
-considers gaseous lost (methane)
NE system
-animal requirements stated as net energy are independent of the diet

Question 19

Contributors to Heat Production due to Feed consumption in an animal at maintenance

Answer 19

• work done in location, prehension and mastication of feed
• work done by movement of digestive tract
• heat of fermentation (if applicable)
• heat increment associated with the metabolic processing of nutrients

Question 20

Contributors to Heat Production due to non food related activities in an animal at maintenance

Answer 20

• maintaining body temperature
• circulation, respiration, maintenance of posture, standing and locomotion
• basic metabolic processes including tissue turnover