L.H. Baumgard1, N.K. Gabler1, J.W. Ross1, A.F. Keating1,

J. Selsby1, J.F. Patience1, S. Lonergan1 and R.P. Rhoads2

1ISU & 2Virginia Tech

baumgard@iastate.edu

Department of Animal Science

Reducing the Impact of Seasonal Loss of Productivity

What’s the Issue?

Heat Stress is not Fever

When environmental temperature nears

the animal’s body temperature, the

animal’s cooling mechanisms are

impaired.

Fever vs. Hyperthermia

Very different biology

Heat Stress is a Global Problem

January 2003, NASA

July 2003, NASA

Heat Stress: Animal Agriculture

Industry Loss

American Dairy Industry 897 million - $1.5 billion

American Swine Industry >$350 million annually(St-Pierre et al., 2003 J. Dairy Sci. E52-E77)

Grow - Finishing $450 million/year(Dr. Steve Pollmann)

Sow - Repro $450 million/year(Dr. Steve Pollmann)

Almost double the economic impact of PRSS

Largest impediment to

food security:Chinese Government

Heat Stress: Economics and Food Security

Cost: (lost productivity, mortality, product quality, health care etc.)

American Agriculture: > $3 billion/year

Global Agriculture: > $100 billion/year

Heat abatement is the primary strategy to mitigate

heat stress

But most developing countries and small stake-holders

lack the resources to afford cooling technology

Heat stress is the largest impediment to efficient

animal agriculture (even in developed countries)

Threatens global food security

Regionalizes animal agricultureSt. Pierre et al., 2003; Baumgard and Rhoads, 2013

Heat Stress will Become More an Issue in

the Future if:

Climate change continues as predicted

Genetic selection continues to emphasis lean

tissue accretion

Increased muscle mass increases basal heat

production

Developing countries become more affluent

Increase consumption of local and American meat

Human population continues to migrate

towards the equator

Animal agriculture will migrate with the consumer

Heat Stress and Industry Issues

Don’t “finish”

Increased variability in market weight

Packing issues with “seam fat” or “flimsy fat”

Seasonal infertility

Wean to estrous; Failure to express estrous; Conception rate

Failure to maintain pregnancy… “slipped liters”

Mortality

Especially late gestation

The pig with the biggest investment

Farrowing parameters

Pigs born alive

Birth weight

Weaning weight

Heat Stress and Gut Health

Massive diversion of blood flow to skin and extremities

Coordinated vasoconstriction in intestinal tissues

Reduced nutrient and oxygen delivery to enterocytes

Hypoxia increases reactive oxygen species (ROS)

Reduced nutrient uptake increases intestinal osmolarity Multiple reasons for increased osmotic stress

Etiology of Heat Stress

(Intestine, Hepatic, Renal, Endothelium, Brain, Muscle, Heart)

Heat Storage

Cytokine Release

(IL-1,IL-6,IL-10, TNF)NO

Ischemia,

ROS & RNS

Cardiovascular Responses

Skin

Dilates

Gut

ConstrictsMuscle

Dilates

Increased

Intestine

Permeability

Endotoxemia

DeathApoptosis

Necrosis

Cell Heat Shock & Ischemia

Heat StrokeCNS & multi-organ damage via

fever, shock, hemorrhage,

stroke & muscle breakdown

InjuryInflammation

Sawka & Young Adv. Exerc. Physiol 2006

Heat Stress and Gut Integrity

Endotoxin (aka. Lipopolysaccharide: LPS)

Component of bacteria cell wall

When bacteria die, LPS is released into

intestine

Normally LPS is prevented from entering

through GIT tight junctions

During HS some LPS enters blood stream

Stimulates inflammation

http://www.sciohealth.co.za

Thermal NeutralHeat Stress

Pig Heat Stress Experiments

Utilized pair-feeding model

Eliminates the confounding effect of dissimilar

feed intake

Need to appreciate the difference between

direct and indirect effects of heat stress in

order to develop mitigation strategies.

Heat Stress Increases Lipid and Decreases

Carcass Lean Content

Pigs

Close et al., 1971; Verstegen et al., 1978; Stahly et al., 1979;

Heath, 1983, 1989; Bridges et al., 1998; Collin et al., 2001

Chickens

Geraert et al., 1996; Yunianto et al., 1997

Rodents

Schmidt and Widdowson, 1967; Katsumata et al., 1990

But, normally growing animals on a restricted-diet

prioritize lean tissue accretion and deemphasize fat

synthesis (Le Dividich et al., 1980; Oresanya et al., 2008)

Heat Stress alters the nutrient partitioning hierarchy

Pig Heat Stress Questions

Direct vs. Indirect Effects of Heat

Indirect effects mediated by reduced feed intake

Production

Metabolism

Leaky Gut?

In Utero Heat Stress

Future body temperature

Future performance

Body composition

Rectal Temperature

36

38

40

42

44

-1 1 2 3 4 5 6 7

°C

Day

TN

HS

PFTN

Pearce et al., 2013

39.3 vs. 40.9 °C

Daily Feed Intake

0

0.5

1

1.5

2

2.5

3

-1 1 2 3 4 5 6 7

kg

Day

TN

HS

PFTN

46% Decrease

Pearce et al., 2013

Pigs: Change in Body Weight

-5

-3

-1

1

3

5

7

9

7

kg

Day

TN

HS

PFTN

a

b

c

P<0.01

Pearce et al., 2013

Pigs: Plasma Energetics

0

0.1

0.2

0.3

0.4

7

mm

ol/

L

TN

HS

PFTN

a

NEFAP<0.01

a

b

0

0.1

0.2

0.3

7

ng

/mL

TN

HS

PFTN

50

75

100

125

150

7

mg

/dL

Day

TN

HS

PFTN

Glucose

0

3

6

9

12

7

mg

/dL

Day

TN

HS

PFTN

BUN

a

b

c

InsulinP<0.01

Pearce et al., 2013

Intestinal Morphology

Thermal Neutral Heat Stress Pair-fed

Pearce et al., 2013

Summary

Reduced feed intake appears to explain the

majority of reduced body weight gain

Actually, HS pigs grow faster than PF pigs

BUT, altered tissue growth

More lipid and less protein

Increased insulin and decreased adipose

tissue breakdown

Leaky gut and endotoxin infiltration

Potential dietary strategies

Primary objective is to control environment

Summary

Reduced feed intake appears to explain the

majority of reduced body weight gain

Actually, HS pigs grow faster than PF pigs

BUT, altered tissue growth

More lipid and less protein

Increased insulin and decreased adipose

tissue breakdown

Leaky gut and endotoxin infiltration

Potential dietary strategies

Primary objective is to control environment

Post-Natal Heat Stress is an Expensive

Problem…..but what about…..

in utero Heat Stress and Future Productivity?…

Objective and Hypothesis

• Determine the postnatal responses in offspring

whose mothers were exposed heat stress during

gestation

– Body Temperature

– Production

– Metabolism

– Body Composition

Constant Heat Stress

Gestational HS

Gestational TN

+0.30°C

(Johnson et al., 2013a)

Diurnal Heat Stress

P < 0.01

Period Difference(from TNTN)

TN + 0.36°C

HS1 + 0.29°C

HS2 + 0.25°C

AVG + 0.27°C

(Johnson et al., 2013b)

Impact of In Utero Heat Stress on Future

Body Temperature

• Pigs exposed to heat stress during gestation have an

increased core body temperature during postnatal

development

• Could be indicative of an increase in core body

temperature “set-point” possibly due to increased

basal heat production

– Likely increases maintenance costs

– May result in decreased performance

– May cause reduced feed efficiency

– May increase time to finish

(Johnson et al., 2013 )

Energy Difference Over Lifetime

• Energetic costs of maintaining increased body

temperature for a lifetime……

• 6.97 Mcal of extra thermal energy produced over lifetime

• $$$$$$$$$

Estimated Economic Cost to Maintain

Increased Body Temperature

• Average Mcal/kg feed (ME) = 3.5 Mcal/kg

• Average feed cost = $300/ton = $300/909 kg = $0.33/kg feed

• GHS pigs = 6.97 Mcal thermal energy / 3.5 Mcal = 1.99 kg feed

• 1.99 kg feed * $0.33/kg = $0.66/pig

• Barn of 10,000 head

– Extra cost = $6,600 per turn in extra feed costs

Gestational Heat Stress and Future Body

Composition??

15% reduction

Protein Accretion Rates

60-80 kg BW

Gestational Heat Stress

Gestational Thermo-neutral

Johnson et al., 2013

32% increase

Adipose Accretion Rates

60-80 kg BW

Gestational Heat Stress

Gestational Thermo-neutral

Johnson et al., 2013

95% increase Gestational Heat Stress

Gestational Thermo-neutral

Adipose: Protein Ratio

60-80 kg BW

Johnson et al., 2013

Impact on nutrient partitioning

Pigs exposed to in utero heat stress

increase postnatal adipose accretion

compared to controls

During the early finishing phase

From 60 to 80 kg BW

Reduced carcass quality and efficiency of

lean tissue production

Likely due to hyperinsulinemia

Long-term implications

Practical Implications

Pigs gestated during summer months or in

regions that experience prolonged periods

of extreme conditions may have increased

propensity for adipose accretion

Reduced carcass quality, efficiency of lean

tissue accretion, and possible economic

losses

Especially in combination with maintained

core body temperature increase

Adrenal

Proteolysis

LPS

Lactate

Pancreas

GIT

Prolactin

Thyroid

Somatotropin

TRH

Pyruvate Alanine

Urea

Lactate

ROS

InflammationLiver

StomachGIT

Macrophage

Adipose Glycogenolysis

Glycogenolysis

GluconeogenesisIGF-1

Insulin

Muscle

Catecholamines

Feed intake

T4; T3

NEFA

Heat Stress: Metabolic

and Physiological

Summary

Baumgard et al., 2014

Seminar Summary

Heat stress markedly alters metabolism

Decreases productivity

Costs everyone in the industry

In utero heat stress is an underappreciated

constraint on efficient production

Combining post-natal and in utero heat stress

together creates an economic burden that

dwarfs most other issues

Seminar Summary

Heat stress markedly alters metabolism

Decreases productivity

Costs everyone in the industry

In utero heat stress is an underappreciated

constraint on efficient production

Combining post-natal and in utero heat stress

together creates an economic burden that

dwarfs most other issues

Acknowledgments

• USDA NRI/AFRI

• # 2005-35203-16041

• # 2008-35206-18817

• # 2010-65206-20644

• # 2011-67003-30007

• # 2014-67015-21627

• Zinpro Inc.

• Elanco Animal Health

• Midwest Dairy Association

• National Pork Board

• Iowa Pork Producers

• TechMix

• Kemin Industries

• ViCor Corp

• Murphy Brown

• Victoria Sanz-Fernandez

• Sarah Pearce

• Jay Johnson

• Rebecca Boddicker

• Amir Nayeri

• Nathan Upah

• Anna Gabler

• Sam Lei

Funding Support

Questions?

http://www.oildrumpigroasterdesigns.com/