Dr. John Patience - A Critical Look at the Science Underlying Feed Efficiency

IOWA STATE UNIVERSITYAPPLIED SWINE NUTRITION

PIJOAN LECTURE: THE METABOLIC BASIS OF FEED/ENERGY EFFICIENCY IN SWINE

John F. Patience &Nestor Gutierrez

Applied Swine NutritionDept. of Animal Science

Iowa State University

http://www.varkensenzo.nl/EN/index.php?file_id=11


HOW IMPORTANT IS FEED CONVERSION?

200220

240260

280300

320340

360380

400420

440460

480500

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

Feed Conversion = 2.63

Valu

e pe

r pig

of 0

.01

impr

ovem

ent

in fe

ed c

onve

rsio

n

Average wean-to-finish feed cost, $/ton

Each feed conversion point is worth about 58 cents per pig

http://www.varkensenzo.nl/EN/index.php?file_id=11


FEED EFFICIENCY IS A DANGEROUS PRODUCTION TARGET WHEN VIEWED IN ISOLATION

• Influenced by feed composition– Energy, amino acid concentration, nutrient balance– Gross deficiencies of other nutrients– Feed processing: grinding, pelleting, enzymes– Feed additives

• Influenced by environmental factors– Temperature, health (huge), access to feed

• Influenced by the pig – Growth rate, protein:lipid ratio, starting and final

weight, mortality


FEED RESTRICTION AND FEED EFFICIENCY

Percent of ad lib

100 93 86 79 72 P-value

Final wt., lb 264.7 262.1 261.6 262.3 264.5 0.1074

Gain, lb/d 2.23 2.03 1.68 1.72 1.45 <0.0001

Carcass fat, % DM 58.2 55.0 51.9 51.2 49.6 0.0058

Carcass protein, %DM 34.4 35.8 39.8 41.8 43.7 0.0011

Patience et al., 2002



Percent of ad lib

100 93 86 79 72 P-value

Final wt., lb 264.7 262.1 261.6 262.3 264.5 0.1074

Gain, lb/d 2.23 2.03 1.68 1.72 1.45 <0.0001

Carcass fat, % DM 58.2 55.0 51.9 51.2 49.6 0.0058


Lipid:protein ratio 1.72 1.58 1.36 1.25 1.16 0.0004

ME intake, Mcal/d 8.24 7.61 7.04 6.43 5.84 0.001




Percent of ad lib

100 93 86 79 72 P-value

Final wt., lb 264.7 262.1 261.6 262.3 264.5 0.1074

Gain, lb/d 2.23 2.03 1.68 1.72 1.45 <0.0001

Carcass fat, % DM 58.2 55.0 51.9 51.2 49.6 0.0058



ME intake, Mcal/d 8.24 7.61 7.04 6.43 5.84 0.001

Feed conversion 2.50 2.50 2.50 2.44 2.63 0.045




Percent of ad lib

100 93 86 79 72 P-value

Final wt., lb 264.7 262.1 261.6 262.3 264.5 0.1074

Gain, lb/d 2.23 2.03 1.68 1.72 1.45 <0.0001

Carcass fat, % DM 58.2 55.0 51.9 51.2 49.6 0.0058



ME intake, Mcal/d 8.24 7.61 7.04 6.43 5.84 0.001

Feed conversion 2.50 2.50 2.50 2.44 2.63 0.045

Days to market 95.5 102.3 123.4 120.8 144.3



HOW DAILY ENERGY INTAKE IS DIVIDED BETWEEN MAINTENANCE AND GAIN

Functions Gain ME intake, Mcal/d

Maintenance - 2.52 (34%)

Protein (lean) gain 138 g/d (16%) 1.46 (20%)

Fat gain 267 g/d (31%) 3.36 (46%)

Total 862 g/d 7.3 (100%)

Assume the diet contains 1.5 Mcal ME/lb and 0.85% SID lysine. The pig weighs about 150 lb, is gaining about 1.9 lb/d (total growout ADG = 1.85 lb) and is eating 4.86 lb of feed/day, giving a feed conversion of 2.58 (total feeder to finish growout FC is 2.85:1).


EXPRESSING “FEED EFFICIENCY”

Expression Calculation Units

Feed:gain Total feed:total gain None

Gain:feed Total gain:total feed None

Energetic efficiency Mcal energy/unit of gain Mcal/kg gain

Feed cost of gain Total dollars spent/total gain Cents/kg gain

Return over feed cost Income (net/gross) – feed cost $/pig

etc

What question are we trying to answer?How are we going to use the information?


2010 PERFORMANCE RECORDS ON 30 MILLION GROW-FINISH HOGS

CaloriesMcal ME/lb

Feed Conversion

Caloric Efficiency

ADGlb/d

Canada 1.41 2.97

USA 1.53 2.72

Source: Agristats, 2011



CaloriesMcal ME/lb

Feed Conversion

Caloric Efficiency

ADGlb/d

Canada 1.41 2.97 1.84

USA 1.53 2.72 1.73




CaloriesMcal ME/lb

Feed Conversion

Caloric Efficiency

ADGlb/d

Canada 1.41 2.97 4188 1.84

USA 1.53 2.72 4163 1.73




CaloriesMcal ME/lb

Feed Conversion

Caloric Efficiency

ADGlb/d

Canada 1.41 2.97 4188 1.84

USA 1.53 2.72 4163 1.73


A critical issue in this comparison is the cost of calories


THE BEST FEED EFFICIENCY DOES NOT NECESSARILY MEAN THE BEST FINANCIAL OUTCOME

We need to strive for optimal feed conversionnot maximal feed conversion

$$

$$

$

$

$$$

$

Ingredient, % Prices$/t

Energy only

Add protein/amino acids

Add minerals/vitamins

Corn 220 54.93 47.65 47.01

Corn DDGS 190 30.00 25.58 27.68

Wheat midds 200 7.60 5.50 -

Soybean meal 300 - 13.50 14.19

Bakery product 230 7.50 7.50 7.50

l-Lysine HCl 2500 - 0.30 0.30

Limestone 50 - - 1.10

Salt 90 - - 0.45

Vitamin premix 1750 - - 0.15

Trace mineral premix 1000 - - 0.12

Phytase 5000 - - 0.08

AV-blend 900 - - 1.16

Cost, $ $210.24 $229.58 $244.00

86.2% 94.1% 100.0%

Diets formulated to meet 1) energy spec only, 2) energy & amino acid specs only, & 3) all nutrients


ENERGY AND FEED EFFICIENCY


NUTRITIONAL ENERGETICS

“Laws of Thermodynamics” are fundamental for

the understanding of energy flux from feed

ingredients to animal tissues and fuel to support

life.


NUTRITIONAL ENERGETICS - BASICS “First” Law of Thermodynamics:

Energy can change form, but cannot be created

nor destroyed

Therefore:

MEI = RE + HE

Where: MEI = Total energy consumed, not excreted in feces or

urine RE = Energy retained in animal tissues HE = Total heat released by the animal.


NUTRITIONAL ENERGETICS - BASICS Second Law of Thermodynamics:

All forms of energy are convertible to “heat”.

Or, energy can be released as heat.


NUTRITIONAL ENERGETICS - BASICS Hess’ Law:

Heat lost in a net chemical transformation is

“independent of metabolic path”

Therefore:

Oxidation of 1 g of Fat to CO2 and H20 in a calorimeter,

produces the same heat as when oxidized by an animal.


HEAT RELEASE FROM DIETARY NUTRIENTS

Carbohydrate Lipid Protein0

1

2

3

4

5

6

7

8

9

10

4.15

9.46

5.66

He

at

rele

as

e, k

ca

l/g

(Ewan, 2001)


IMPACT OF DIET NE AND FEEDING LEVEL ON CARCASS ENERGY CONTENT

Item ISG 2.15 2.26 2.37 70 80 100 SEM

GE1 1.59 2.63 2.66 1.76 1.64 1.65 1.76 0.02

GE2 1.62 1.66 1.70 1.49 1.67 1.69 1.79 0.02

GE1 = measurement directly using bomb calorimetry; GE2 = determination from carcass protein and lipid content, multiplied by 5.66 and 9.46, respectively

Source: Oresanya et al., 2008


SCHEMATIC REPRESENTATION OF ENERGY FLOWS FOR FEED ENERGY CONTENTS

GE DE ME NE

NEm

NEprotein

NElipid

NEmilk

Heat increment (HI)

Urinary energy (UE)

Fecal Energy (FE)


ENERGY SYSTEMS NE content of a feedstuff:

NE = NEp + NEm

NEp = NE for production

NEm = NE for maintenance functions

General procedures for estimating NEp and NEm

Respiration chambers

Comparative slaughter (Linear regression analysis)

DEXA


CURRENT ENERGY SYSTEMS

DE system used in the Australia, decreasingly in

Canada

ME system used in the US, China, South America (?)

France (INRA), the Netherlands (CVB), Spain and the

U.K. use NE system

Denmark uses the PPE system


CURRENT ESTIMATION OF ENERGY REQUIREMENTS FOR MAINTENANCE AND PRODUCTION

“Partition of heat (energy intake used for maintenance

and production) into meaningful physiological

components is complex and controversial”

– (Baldwin, 1995)


INTAKE ENERGY FOR MAINTENANCE

Maintenance requirement

Energy intake required to maintain an energy balance

of zero

Determined in fasting animals using respiration

chambers.

Principle: Heat loss of the animal is proportional to

its surface area. “Surface Law”

FHP = a X BWb


NEM FOR GROWING PIGS

Location BW NEm

France (1994) 35 kg 179 kcal/kg BW0.6

France (2006) 35 kg 117 kcal/kg BW0.6

Denmark (1983) 20 kg 148 kcal/kg BW0.6

MEm

USA / NRC (2012)

Growing-finishing 197 kcal/kg BW0.6

(Adapted from Kil, 2009)


COMPONENTS OF HEAT PRODUCTION

(de Lange and Birkett, 2005)

Tis

sue

En

erg

y

Energy Intake

Slope = kg

FCAT

FHP

MEm

MEI

0.0

-

+

Slope = km

E. retention


COMPONENTS OF HEAT PRODUCTION

(de Lange and Birkett, 2005)

Tis

sue

En

erg

y

Energy Intake

Slope = kp

FCAT

FHP

MEm

MEI

0.0

-

+

Slope = km

E. retention

Slope = kl


FACTORIAL APPROACH TO ESTIMATE TOTAL ME INTAKE (MEI)

MEm = FCAT / Km

FCAT = Total heat production during fasting

Km = “Efficiency” of use of ME for maintenance

RE = (MEI – MEm) * Kg

RE = Energy retained in body tissues

Kg = “Efficiency” of use of ME supplied above maint.

Total ME required for a pig can be expressed as:

MEI = FCAT/Km + RE/Kg


FACTORIAL APPROACH

Is a “statistical model”:

Represent energy required by an animal (i.e. Mcal/d)

Energetic contribution of a feed ingredient to meet

these requirements (i.e. Mcal/kg)

Requirements and energy content of feed ingredients

are determined empirically (best-fit relationships)

Inappropriate to speculate on their physiological

meaning


PROBLEMS OF THE FACTORIAL/STATISTICAL APPROACH

Exponents and coefficients lack biological meaning

Lipid and protein deposition rates affect costs of

maintenance

Increased maintenance requirements in fast

growing genotypes

FHP estimates measured at zero energy retention

Representative of a mature rather than a growing

animal

Exclude dynamic processes: growth, lactation etc.

Difficult to separate costs of maintenance vs. growth


PROBLEMS OF THE FACTORIAL/STATISTICAL APPROACH (CONT.)

High variability of maintenance requirements due to:Sex, age, genetics, previous plane of nutrition,

environment Empirical model

Useful “only” in conditions similar to which it was developed or adjusted

Statistical limitationsLimited # of parameters Independent variables (i.e. Km, Kg) are highly inter-

correlated High variability within independent variables

BIOLOGICAL ENERGETIC EFFICIENCIES (BLACK, 1995; VAN MILGEN ET AL. 2001)

Lipids

Body lipid deposition

Starch

ATP production

Glucose Fiber/Residue(fermentable)

0.900.74

0.62

0.66

0.68 0.50

(Black, 1995; van Milgen et al. 2001)


ENERGETIC EFFICIENCY (NE/DE, %)

Protein Fat Starch Sugars0

102030405060708090

100

(Stein, 2009; Birkett and de Lange, 2001; Noblet et al., 1989)

GE

DE

ME

NEp

NEg

Energy in feces

NEl

NEm

NE

Energy in urine

Energy in gases: CH4 + H2

Heat increment

Adapted from Ewan, 2001Adapted from Oresanya et al., 2005

100%

85%

82%

56%

Km

Kl Kp

29%27%

Energy utilization in the weanling pig

IngredientFactors

AnimalFactors


ENERGY EXPENDITURE IN SEVERAL MAINTENANCE FUNCTIONS

(Adapted from Baldwin, 1995)

1BMR = Basal Metabolic Rate. Equivalent of FHP in humans


COMPONENTS OF MAINTENANCE

Service functionsCirculation, coordination, respiration, excretion

Membrane transport – active transport of ionsNa+ transport

Protein turnover Basal activity Additional functions

Extra activitySocial stress Immune responseCold stress

(Knap, 2009)


TAKE HOME MESSAGES

1. Feed efficiency is a valuable monitoring criterion, but a poor driver of management decisions

2. The value of 1 pt in feed conversion has almost doubled in the past year, so our thinking must adjust

3. Maintenance represents 30 to 35% of total energy intake. Anything that can be done to lower maintenance requirements will increase amount of energy available for gain

4. Meeting the energy specifications of a diet represents about 85% of the total diet cost

5. Energy metabolism in the body adheres to all of the laws of thermodynamics


TAKE HOME MESSAGES

6. Understanding the various constituents of energy utilization (factorial approach) is critical to success in optimizing feed efficiency

7. If you have not already done so, start reading about “net energy” as it will become increasingly prominent in the U.S. pork industry of the future

8. The efficiency with which the pig uses dietary energy depends on the source of the energy and on its fate in the body

9. Reducing “maintenance” is one strategy for improving feed efficiency


APPLIED SWINE NUTRITION TEAM

Business

Dr. John Patience - A Critical Look at the Science Underlying Feed Efficiency