Dietary Energy

Energy

the ability to do work; not a nutrient

Heat energy

In animal nutrition, the unit for energy is expressed in terms of ___

Calorie (Cal)

the basic measure of energy which is the amount of heat needed to raise the temperature of one gram of water by 1 °C(14.50 to 15.5 °C); equal to 4.184 Joule

Kilocalorie(Kcal)

1,000 Cal

Megacalorie (Mcal)

1,000,000 calories or 1,000 kcal; also referred to as therm

Joule (J)

1 newton metre; equal to 0.24 Cal

Bomb Calorimeter

The energy content of a matter is determined using an instrumant called __

Carbohydrates, Protein, and Fats

Feeds contain ____ which are sources of energy.

Loss through feces

first loss of energy during digestion; the energy from the

undigested portion of the feed; also includes small amount of energy from wornout cells from the intestinal walls, enzymes and intestinal micro-flora;

Digestible Energy

when fecal

energy is deducted from the gross energy, ___ value of the feed is obtained

Loss through gaseous production of digestion

second source of energy loss; during the digestive processes, fermentation of feeds produce gases (majority is CH and traces of H,, CO, acetone, ethane, and H,S) which have some energy value

5,000 Kcal, 10%

extensive in ruminant animals (about mature cow may lose more than ___ per day through gaseous losses which may account as __ of her gross energy consumption); insignificant energy loss, hence usually ignored, in non-ruminants (e.g. swine and poultry) which have small gaseous products of digestion

Loss through urine

third source of energy loss; represents nutrients that have been digested and absorbed into tge body but are excreted ___; chiefly nitrogenous end products of protein metabolism and breakdown products of body tissues

Protein Content

the amount of urinary energy is affected largely by the ___of the diet

Loss through heat increment

the increase in heat production following consumption of feed when the animal is in a thermally neutral environment; the energy cost of breaking down and absorbing feeds; the amount differ among energy nutrients that are metabolized such that digestion of fats requires lower energy (absorption of 100 Cal of fat requires 6 Cal of energy compared d to protein (absorption of 100 cal of protein requires 4 / Cal of energy

heat increment is divided into

Heat of fermentation

Heat of nutrient metabolism

Heat of fermentation

the heat produced in the digestive tract as a result of microbial action, which is quite extensive in ruminant animals

Heat of nutrient metabolism

the heat produced by the work which the body must do to digest, absorb and metabolize nutrient.

Gross Energy (GE)

• Refers to the heat generated when a feed is completely oxidized/burnt.

• To measure, a known amount of sample is placed a bomb calorimeter, and then oxygen is used to fill the chamber so that the sample will be completely oxidized.

Digestible Energy (DE)

• The amount of energy apparently absorbed from a feed.

• Obtained by subtracting fecal energy. DE = GE - FE

Metabolizable Energy (ME)mm

Determined by subtracting energy losses in urine (UE; energy from non- utilized absorbed compounds from the processes (U processe a dies protects on endogenous origin (U_E)) and combustible gases from DE

• ME = DE - (UE + GE*)

• Determination must involve collection of feces, urine, and gaseous losses.

Net Energy (NE)

• Determined by subtracting energy losses due to heat increment (HI; includes heat of fermentation and nutrient metabolism) from ME.

• NE = ME - HI

Total digestible nutrients (TDN)

• a figure which indicates the relative energy value of a feed to an animal.

• expressed in pounds or kilograms or in percent (pound or kg of TDN per 100 pounds or kg of feed).

Limitation of the TDN System

• It overestimates the value of roughages because more energy spent in chewing of such feeds remains unaccounted.

• Only the loss in feces is accounted.

• Not a measure that has direct relevance to net energy or energy metabolism in general