The document discusses energy partition in animals. It defines various terms related to energy such as gross energy, digestible energy, metabolizable energy, and net energy. Gross energy is the total energy in feed. Digestible energy is gross energy minus energy lost in feces. Metabolizable energy is digestible energy minus losses in urine and gases. Net energy is metabolizable energy minus heat produced during digestion and metabolism. The document also discusses energy requirements for maintenance and production. Providing too little or too much energy can impact growth and health of animals.

1. Topic : Energy partition
K.Prashanth Kumar
Rvm/15-13

2. Energy
• The term energy is derived from two greek words
en = in & ergon = work.
•There are variety of definitions and descriptions of energy
depending upon whether energy is being considered in
reference to its properties in the physical or the biological
sciences.
•In the physical sciences , energy is designated broadly to
be work or anything that can be converted to work.
•Most of the energy on earth comes originally from the
sun although molecular energy is the most vital and useful
form of energy to animals.

3. • Forms of energy: (1) mechanical (2) thermal (3) electrical
(4)light (5) nuclear (6)molecular
• Energy stored in plants in the form of carbohydrates, lipids,
and protein through photosynthesis .the stored chemical
energy become available to man and animals.
Basic terminology of energy:
• Calorie(cal): The amount heat needed to raise the
temperature of 1 gram of water to 15.5°C from 14.5 C
(now usually defined as 4.1868 joules).
• Kilocalorie(kcal): The amount heat needed to raise the
temperature of 1 kilogram of water by 1 c .
• Megacalorie: equivalent to 1000 kcal
1 kilocalorie = 4.184 Kjouls
1 KJ= 0.239 Kcal

4. GROSS ENERGY
FAECAL ENERGY DIGESTIBLE ENERGY
URINARY ENERGY
APPARENT
METABOLIZABLE
ENERGY
TRUE
METABOLIZAB
LE ENERGY
METABOLIC &
ENDOGENOUS
ENERGY LOSES
HEAT INCREMENT
NET ENERGY
NEp
Eggs
Growth
Feathers
NEm
BMR
Activity
Body temp. regulation
HEAT
PROD
UCTIO
N

5. • Gross energy(GE): Gross energy is the amount of heat
produced when a feed is completely burnt in a Bomb
calorimeter containing 25 to 30 atmosphere of oxygen in a
Bomb calorimeter . OR Total energy present in the food.
• The % of gross energy that can be taken into animal body and
used to support the metabolic processes depends upon the
ability of animal to digest feedstuffs.
• The GE content of the feed does not indicate the actual
energy available to the bird.
• Faecal energy(FE): FE is gross energy of the faeces. It
consists of the undigested feed and of metabolic
fraction(digestive fluids and abraded mucosa) of faeces.
• FE= dry wt of the faeces × GE of faeces per unit of dry wt.

6. • Gross energy intake(kcal/g) =
gross energy in diet x dry matter intake
• Gross energy(kcal/g) /gm output(kcal/g) =
gross energy in excreta x dry matter output
• Gross energy of excreta/ gm DMI(kcal/g) =
Gross energy /gm output
dry matter intake

7. • Apparent Digestible energy(DE): digestion
represents physical , chemical processes which takes place in
the G.I tract and result in breaking down the complex
chemical material in feeds into the smaller molecules that
can be absorbed and used by the animal .
• This absorbed energy termed as Digestible energy.
OR
• DE determined by subtracting faecal energy from GE of
feed.
• DE labelled as apparent because the faecal energy includes
energy of spent digestive fluids and abraded intestinal
mucosa.

8. • Urinary energy (UE): UE is the gross energy of
the urine. It includes the energy content of
the non-oxidised portion of the absorbed
nitrogenous products, primarily urea in
mammals and uric acid in birds and the
energy in the endogenous fraction of the
urine.
FE-22.7% of GE lose
UE-4.5% of GE lose
Gaseous lost are insignificant
Remaining 72.7% retained in the body as ME

9. • Urinary energy (UE): UE is the gross energy of the
urine. It includes the energy content of the non-oxidised
portion of the absorbed nitrogenous products, primarily
urea in mammals and uric acid in birds and the energy in
the endogenous fraction of the urine.
• Apparent Metabolizable energy(ME): is the
gross energy of the feed consumed minus the gross
energy contained in the faeces, urine, and gaseous
products of digestion. For poultry the gaseous products
are usually negligible, so ME represents the gross
energy of the feed minus the gross energy of the
excreta.
• A correction for nitrogen retained in the body is
usually applied to yield a nitrogen-corrected ME (MEn)
value.

10. • Nitrogen corrected(MEn ): the ME value of a feed
will vary according to whether amino acids it supplies are
retained or are deaminated and their nitrogen excreted in
the urine as urea or uric acid.
 body nitrogen, when catabolised, is excreted as energy
containing products like uric acid.
 AME values are thus influenced by the amount of
nitrogen retained
 For this reason, ME values may be corrected to zero N
balance by deducting for each 1 gm of N retained or by
adding for each 1 gm of N catabolized.

11. • True metabolizable energy (TME): for poultry is
the gross energy of the feed consumed minus the
gross energy of the excreta of feed origin. A
correction for nitrogen retention may be applied
to give a TMEn value.
• For poultry the usual correction factor is 8.22 Kcal
GE/g N retained or excreted.
• This is energy value of uric acid when oxidized
completely in bomb caloriemeter .

12. AME (kcal/kg as is) =
gross energy of feed − gross energy of excreta
• Gross energy of excreta/ gm DMI(kcal/g) =
Gross energy /gm output
dry matter intake
AMEn (kcal/kg as is) =
gross energy of feed − gross energy of excreta
−(NRxK))
NR is the Nitrogen Retention, which is assumed to be (20% of body weight
gain/loss)/6.25, and K is the constant which equals to 8.21 kcal/g nitrogen
retention

13. ME content of different feed stuffs
Energy ingredient ME( kcal/kg)
Maize 3300
Jowar 3000
Bajra 2640
Rice(broken) 2600
Wheat 3100
Barley grain 2640
Rice polish 2700
Ragi 2950
Tapioca flour 3300
Vegetable fat 8800

14. Cont…
Ingredient ME (kcal/kg)
Soya extract 2500
Soya meal 2250
Groundnut extract 2690
Groundnut meal 2400
Rapeseed extract 1900
Sunflower extract 1540
Sesame extract 2200
Fullfat soya 3300
Fish meal 2180
Meat&bone meal 1848
Ricebran 1800
Wheat bran 1400
Salseed extract 2500
Molasses 2000

15. • Metabolizable energy provides a useful measure of the
gross energy but such retained energy is not used 100%
efficiently for growth ,egg production etc.
• During these metabolic processes ,some 15% of energy
will be ‘wasted’ as heat this is referred as heat
increment.
• Heat increment(HI): it is the increase in the heat
production following consumption of food when the
animal is in a thermo neutral environment.

16. • HI due to :
Ingestion
Digestion
Nutrient metabolism(specific dynamic action)
Excretion
• HI is due to heat of fermentation (HF) i.e heat
produced in digestive tract as a result of microbial
action, and heat of nutrient metabolism (HNM) i.e
heat produced in intermediary metabolism of
absorbed nutrients.
• The energy of HI is wasted except when the
temperature of environment is below the critical
temp when it is used to keep the body warm.

17. • A measure of heat output i.e HI can be
obtained from estimation of Respiratory
Quotient, which is an estimation of the
volume of co2 produced , divided by the
amount of c2 consumed.
• Usually RQ between 0.7-1.0
• RQ value for- CHO’s-1
Fats-0.7
Protein-0.67-0.83
• Low RQ’s results from synthesis of carbohydrates
from fats, and also from the catabolism of proteins.

18. • Net energy(NE): is metabolizable energy minus the energy
lost as the heat increment. NE may include the energy used
for maintenance only (NEm) or for maintenance and
production (NEm+p). Because NE is used at different levels of
efficiency for maintenance or the various productive
functions, there is no absolute NE value for each feedstuff.
NE = AME - HI

19. • NEM is the fraction of total NE expended to keep
the animal in energy equilibrium.NEm for a
producing animal is diff from non producing
animal of the same weight, because of changes in
amounts of hormones produced and difference in
voluntary activity. it includes basal metabolism,
voluntary activity and maintain body temp.
• NEp : is fraction of net energy required for
growth,fattening,milk,wool,egg etc.
• Net energy for production and maintenance can
also be ascertained by direct estimates of energy
deposited in products.

20. • Fraps & coworkers –estimating productive energy
of feeds by comparative slaughter techniques.
• The energy requirement of an animal can be partitioned
into 3 main groups
1)energy for maintenance
2)energy for production
3)energy for extended activity

21. • Basal metabolism is the minimum energy required by
a non-producing animal at rest to carry on its essential
processes of life, such as breathing, circulation of blood,
maintenance of body temp and repair of daily wear and
tear of body tissues.
• Basal metabolism is usually measured with a fasting
animal under normal conditions.
• Studies with fasted day old chicks shown that basal heat
production is around 0.0055 kcal per Gram body weight
per hour.
• For adult hens – 0.003 kcal per gram body weight per
hour.

22. • The approximate net energy requirement of a 40
gram chick would be:
= 0.0055 x 40g x 24 hr
= 5.28 kcal / day
• Energy for maintenance was related to surface
area of the animal.because surface area of an
animal is proportional to approximately 2/3 of its
body weight.
• Brody and kleiber estimated the basal heat
production with animals ranging from a mouse
to Horse. They arrived at a value around 70 kcal
per kg.75 body weight.

23. • ME requirements are 18% higher than net energy
requirements. this is due to heat produced
during metabolism.
• For proteins it is 30%,CHO’s 15%, and fat 10%.
• This avge 82% conversion of ME to NE is for diets
that are of high quality and well balanced.
• 82% ME is NE.

24. • since the chicken has a higher body
temperature than mammals its energy
expenditure for mantenance is greater.
ME REQUIREMENT FOR BROILERS :
(Leeson and Summers, 2001)
• NEm = 83 x b.wt.0.75
• MEm = NEm (82% of ME is NE)
0.82
• MEa = MEm x 0.5

25. Example :
Hen weighing 1.3 kg
Nem = 83 x 1.3 kg 0.75
= 83 x 1.22
=101 kcal/hen per day
• considering the ME requirement is 82% of NE
value --
Mem= 101/0.82
=123 kcal per hen per day

26. • Mem (activity) = Mem x 0.5
activity increment - 50% in broiler
- 30% in layer
• MEgrowth=
(Targeted wt.gain x 0.18 x 4.0)+(Targeted wt.gain x 0.15 x 9.0)
 For 0.18gm cp in meat deposition 4 kcal/g energy required.
 For 0.15gm fat in meat deposition 9 kcal/g energy required.
• ME required kcal/day = MEm + MEa + MEgrowth
no.of days in the period

27. Example:
• Body wt. of the bird at start of period: 0.3kg
• Metabolic body wt.(w 0.75) = 0.30.75
= 0.405
• Expected wt gain in period = 120gm
• Period = 7 days.
Mem = 83x0.405/0.82
= 40.89
MEa= MEm x 0.5=40.89x0.5
=20.44

28. MEgrowth = (120x0.18x4.0)+(120x0.15x9.0)
= 86+162 = 248 / 7 days.
MEgrowth/day = 248/7= 35.4
ME required/day=40.89+20.44+35.4
=96.73

29. • Energy for voluntary activity (VAE) consists of
energy needed in getting up, standing,
moving, drinking etc.
• Heat to keep the animals body warm(HBW) is
additional heat needed to keep the animals
body warm when the environmental temp is
below critical temp.
• Total heat production(HP)= HI+NEm
• NEP or energy retention =ME-HP

30. What happens when low energy diet fed to
birds??
• Chickens increase their feed consumption as the energy
content of the diet reduced, deficiency of energy
produced only by very using very low energy diets.
• The lower energy levels of energy
• -2600 kcal in moderate &cool environment
per kg of diet
- 2400 kcal in warm environments.
• Signs: The growth is reduced and the amount of fat
deposited in the carcass is decreased.

31. • Under energy starvation conditions body energy
stores are utilized in the following sequence:
1) first, the small amounts of glycogen normally
stored in the body are exhausted.
2) secondly, loss of libile protein reserves and
initiation of fat catabolism. Body protein is
associated with about 80% water then this first
loss of protein causes sudden loss in weight
,subsequent loss of fat reserves causes slower
rate of wt. loss.
3) continuation of loss of fat reserves from adipose
tissue.

32. • Effects of energy excess:
• A dietary excess of energy occurs whenever the ratio
of energy t protein and amino acids is in excess of
that needed by the animal for normal growth,
production, activity and maintenance.
• Slight excess of energy cause no detectable signs
other than extra deposition of fat and slight decrease
in growth rate.
• This is due to excess dietary energy levels the animal
obtain sufficient energy with low feed consumption,
thereby usually reducing their amino acid intake
below that needed for optimum growth or
production.
• under such abnormal conditions growth may cease
entirely, the chickens may become fat and shows
signs of vit and protein malnutrition.

33. • Experimental work demonstrated that diets
containing as much as 35-40% fat and 45-50%
protein , with little or no carbohydrate , and with
energy values as 5000 kcal ME/kg, will produce
excellent growth in young chicks, as along as the
protein and amino acids levels are maintained at
optimum ratios to the bird energy intake.
• Signs – increased growth rate and obesity in
mature birds and obesity in juveniles.
EODES- erratic ovulation and defective egg
syndrme seeen in heavy breeders fed excess
energy .

34. • Birds multiple ovulate, often with 2-4 mature ova
being released from the ovary at any one time.
Such EODS rarely occurs.
• Force feeding of geese is still practiced in some
countries , for production of “fois gras”. with
excess energy in their system, liver size in these
geese can be 4-6x normal and liver fat contents
reaches 40% on a wet at. Basis.

35. Reference:
• Scott’s Nutrition of the chicken(4th edition)
−S.Leeson & J.D.Summers
• Hand book of poultry nutrition
−V.Ramasubba Reddy
− Dinesh T.Bhosale
• Nutrient requirements of poultry
-ICAR published

36. Thank you