Dr. Nick Gabler - The impact of PRRSV on feed efficiency, digestibility and tissue accretion in...

Department of Animal Science

The impact of PPRSV on feed

efficiency, digestibility and

tissue accretion in grow-finisher

pigs

Nicholas Gabler

Assistant Professor

Department of Animal Science

Introduction - PRRSv

• Porcine Reproductive and Respiratory Syndrome Virus (PRRSv)

• Estimated to cost the U.S. Pork industry $1.8 million per day (Holtkamp et al., 2011)

• Sows• Reproductive and respiratory problems

• Litters with normal, weak, stillborn, and mummies

• Anorexia, agalactia in sows

• Early gestation – abortions

• Grow-finisher pigs• Ill-thrift and poor growth common

• Alone, rarely severe in older pigs

• Infected pigs more prone to secondary infections and thus increased mortality risk

Department of Animal Science

Increased cortisol and stress related signals

Loss of AA/Energy

and metabolic shift

Depressed Anabolic

Sensitivity; Increased Catabolic

Activity

Stress/Immune Challenge

Growth Potential is Reduced

Altered Metabolic Demand

Reduced Efficiency

Increased local production of cytokines

Disease/inflammatory challenges require energy and

amino acids

Department of Animal Science

Investigators

• Nicholas Gabler (ISU)

• Kent Schwartz (ISU)

• John Patience (ISU)

• Jack Dekkers (ISU)

• Locke Karriker (ISU)

• Tom Burkey (UNL)

• Jack Odle (NCSU)

• Gene Gourley (Swine Graphics)

• Mark FitzSimmons (MAF Veterinary Services)

• Chris Sparks (Choice Genetics)

Department of Animal Science

Introduction

How does an immune challenge alter feed intake and digestibility?

Does an immune challenge alter tissue accretion?

What is the impact of a disease challenge of pig feed efficiency?

Do sick pigs have altered nutrient requirements?

How do we feed and manage sick pigs?

Department of Animal Science

Objective and hypothesis

• In grow-finisher pigs, to characterize the impactPRRSv challenge has on

• Feed efficiency, energy and nutrient digestibility

• Body composition and tissue accretion

• Post-absorptive metabolism

• We hypothesize that the reduction in growth ratesduring PRRSv infection is associated with reducedenergy and nutrient digestibility

• Furthermore, this translates to reduced lean tissueaccretion and efficiency of lean gain

Department of Animal Science

• 60 Choice Genetics maternal line gilts

• 73-75 lbs BW

• Littermates split between two barns

• 6 pigs/pen

• 5 pens/trt

• Feed corn-soybean-DDGS diets

• Immune system stimulation

PRRSv inoculation (I.M.)

• Northern Iowa isolated PRRSv (Stanhope region)

Control saline (I.M.)

• Measure performance, tissue accretion, digestibility

and PRRSv titers over time

Methodology

Department of Animal Science

adaptation 42-d

Period 1(d0)

Injection with saline or PRRSv

PRRSv-

n=30

PRRSv-

n=30

35-d

Period 2

Methodology

PRRSv-

n=30

PRRSv+

n=30

35-d

Period 3

Body

composition

(d-1)

Body

composition

(~ d 80)

Body

compositio

n

(d 42)

Market

(~ d

115)

Department of Animal Science

General diet – Four PhasesIngredient %

Corn 53.63

SBM 23.00

DDGS 20.00

Soybean oil 1.00

Lime 0.85

Lysine 0.63

Salt 0.35

Akey 2# VTM 0.10

Heat Stable Optiphous 2000 0.02

Threonine 0.23

Aliment 0.20

TiO2 0.40

Calculated

ME, Mcal/kg 3.24

Total Lysine, % 1.45

TID Lysine, % 1.28

Met and Cys, % 0.77

Department of Animal Science

PRRSv challenged pigs

Parameter Wk 0 Wk 1 Wk 3 Wk5 Wk10

Log+1 QPCR PRRS titer 0.0 4.6 5.9 0.0 0.0

PRRSX3 EIA titer 0.0 0.2 0.2 1.2 0.9

Department of Animal Science

PRRSv model (IPPA# 12-113)

Parameter Day 0 Day 7 Day 14 Day 28 Day 57 SEM P-value

Body weight (kg) 17.1 20.3 23.1 30.7 55.6 0.94 <0.001

Log+1 QPCR PRRS titer 0.0 4.6 1.5 0.0 0.0 0.12 <0.001

PRRSX3 EIA titer 0.0 0.5 1.8 1.9 2.0 0.08 <0.001

0.0

1.0

2.0

3.0

4.0

5.0

0 20 40 60Days Post-Inoculation

log+1 QPCR

X3 EIA

Department of Animal Science

Weekly Performance

• Inoculated pigs at ~72-75 lbs BW (week 0)

• Market pigs ~280-285 lbs

0

20

40

60

80

100

120

140

0 3 6 9 12 15 18

Bo

dy w

eig

ht,

kg

Week

PRRSv+

PRRSv-

14 days

Department of Animal Science

Overall Performance (105-119 days)

ADFI ~6% difference ADG ~10% difference

G:F ~7% difference Carcass G:F ~6% difference

0.0

0.5

1.0

1.5

2.0

2.5

AD

FI (k

g/d

)

a, b

P<0.05

0.0

0.2

0.4

0.6

0.8

1.0

AD

G (

kg

/d)

PRRSv-

PRRSv+

0.0

0.1

0.2

0.3

0.4

0.5

G:F

a

b

a

b

a

b

0.0

0.1

0.2

0.3

0.4

0.5

Ca

rca

ss

G:F

2.05

0.410.44

1.930.80

0.89

0.320.30

Department of Animal Science

Weekly Performance

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Wk1 Wk2 Wk3 Wk4 Wk5 Wk6 Wk8 Wk10 Wk15 Wk17

AD

G (

kg

/d)

PRRSv-

PRRSv+

* P<0.05 within week

0.0

1.0

2.0

3.0

Wk1 Wk2 Wk3 Wk4 Wk5 Wk6 Wk8 Wk10 Wk15 Wk17

AD

FI (k

g/d

)

-32%

* * * *

* * * *

-50%

Department of Animal Science

*

*

* *

Weekly Performance

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Wk1 Wk2 Wk3 Wk4 Wk5 Wk6 Wk8 Wk10 Wk15 Wk17

Ga

in:F

ee

d

PRRSv-

PRRSv+

-27%

* P<0.05 within week

-25%

Department of Animal Science

• So what is the impact of PRRSv on body

composition and tissue accretion?

Department of Animal Science

DXA = Dual X-Ray Absorptiometry

Predicts:

Total mass (g)

Lean (g)

Fat (g and %)

Bone mineral

density & content

Department of Animal Science

Department of Animal Science

Whole body composition (~80 days post challenge)

• PRRSv challenge alters whole body composition

• What about tissue accretion rates?

Parameter PRRSv- PRRSv+ SE p-value

DXA predicted BW, g 99,063 90,318 1,981 <0.01

Fat, g 21,820 19,200 539.5 0.001

Lean, g 75,859 69,718 1,112.5 0.001

Predicted Protein, g 14,224 13,072 208.6 <0.01

BMC, g 1,384 1,400 34.0 0.64

Lean, % 76.6 77.5 0.49 0.06

Fat, % 22.1 20.9 0.48 0.018

n=30 gilts/trt

Department of Animal Science

Whole Body Tissue Accretion Rates

(0-42 days and ~42-80 days post challenge)

ParameterPeriod (0-42days)

SE p-valuePeriod (42-80days)

SE P-valuePRRSv- PRRSv+ PRRSv- PRRSv+

Lean, g/d 609 470 13.9 0.001 661 641 29.8 0.51

Protein, g/d* 122 94 2.61 <0.01 132 129 5.59 0.68

Fat, g/d 154 110 7.57 0.001 268 241 12.6 0.036

BMC, g/d 11.4 9.7 0.44 0.004 12.9 12.7 0.53 0.70

Total, kg/d 0.77 0.59 0.019 0.001 0.94 0.89 0.018 0.17

n=30 gilts/trt

Adjusted for initial (DXA -1 day) data

*Predicted based on calibration curves (Chemical protein = DXA lean x 0.2006 – 0.6611)

Department of Animal Science

Whole Body Tissue Accretion Rates

(~0-80 days post challenge)

ParameterPeriod (0-80days)

SE P-value

PRRSv- PRRSv+

Lean, g/d 633 547 13.5 0.001

Protein, g/d* 126 109 2.53 0.001

Fat, g/d 205 169 7.05 0.001

BMC, g/d 12.0 11.0 0.35 0.006

Total, g/d 0.85 0.72 0.018 0.001

n=30 gilts/trt

Adjusted for initial (DXA -1 day) data

*Predicted based on calibration curves

(Chemical protein = DXA lean x 0.2006 – 0.6611)

• PRRSv challenge significantly reduces tissue accretion rates (15-20%)

• Pigs rebound after 6 weeks to have equal performance

• No compensatory growth observed

Department of Animal Science

• So what is the impact on total tract digestibility?

Department of Animal Science

adaptation 42-d

Period 1(d0)

Injection with saline or PRRSv

PRRSv-

n=30

PRRSv-

n=30

35-d

Period 2

• Fecal grab samples collected

• Day 19-23

• Day 65-70

• Pooled within pig

• Diet marker Titanium dioxide

• Measured feed and fecal

• Dry matter, Nitrogen (N) and energy content

• ATTD coefficients calculated

Apparent total tract digestibility (ATTD)

35-d

Period 3

Body

composition

(d-1)

Body

composition

(~ d 80)

Body

compositio

n

(d 42)

Market

(~ d

115)

Department of Animal Science

Effects of 21 d PRRSv challenge on digestibility

• PRRSv challenge reduces apparent total tract digestibility (ATTD)

19-22 days post challenge

• Coupled with reduced feed intake, contributes to poor performance

Parameter PRRSv- PRRSv+ SE P-value

ATTD coefficients, %

Dry matter 83.9 81.3 0.54 <0.001

Nitrogen 81.8 77.3 0.84 <0.001

Gross Energy 81.0 77.8 0.64 <0.001

n=15 gilts/trt

Department of Animal Science

Effects of 65 d PRRSv challenge on digestibility

• PRRSv challenge also reduces apparent ATTD coefficients 65-70

days post challenge

• Feed intake is similar between the treatments at this point

Parameter PRRSv- PRRSv+ SE P-value

ATTD coefficients, %

Dry matter 81.5 79.8 0.62 0.008

Nitrogen 80.1 78.0 0.82 0.018

Gross Energy 78.1 76.3 0.76 0.020

n=15 gilts/trt

Department of Animal Science

Percentage difference between digestibility

coefficients due to PRRSv challenge

• PRRSv challenge still alters total tract digestibility

coefficients 65-70 days post challenge

% Differences Dry matter Nitrogen Gross Energy

Day 19-22 3.19 5.55 3.90

Day 65-70 1.98 2.40 2.11

n=15 gilts/trt

Department of Animal Science

• So what is the impact on carcass performance and

the bottom line?

Department of Animal Science

Plant data

• Leaner pigs & reduced yield due to PRRSv infection

Live weight

(lbs)

Carcass

(lbs)

Yield

(%)

BF

(in.)

Loin Depth

(in.)

Lean

(%)

PRRSv- 271 208 76.7 0.73 2.77 55.4

PRRSv+ 279 210 75.4 0.59 2.77 56.3

Department of Animal Science

Economic Analysis based on the 30 pigs/trt

Assumption if taken to same live weight PRRSv- PRRSv+ Difference

ADFI (lbs/d) 4.52 4.25

Feed days 105 119 +14 d

Total feed (lbs) 475 506 +31 lbs

Feed Cost @ $350/ton $83.10 $88.50 ($5.40)

Barn cost @ $0.10/pig/d housing $10.50 $11.90 ($1.40)

Carcass wt (lbs) 208 210 +2 lbs

Carcass value

(Standardize base price $71.33 cwt)

$161.52 $162.18 $0.66

Estimated cost of PRRSv per pig ($6.14)

Assumption if same age PRRSv- PRRSv+ Difference

Feed costs @ $350/ton and 105 days $83.10 $78.09 ($5.01)

Body weight (lbs) 271 246

Carcass weight (lbs) 208 185

Carcass value ($71.33 cwt) $161.52 $143.66 $17.86

Estimated cost of PRRSv per pig ($12.85)

Department of Animal Science

What is the metabolic cost of disease challenge?

• Energy

• Immune response

• Nitrogen clearance

• Changes in metabolic rates

• Amino acids

• Synthesis of immune cells and components

• Gluconeogenesis

Department of Animal Science

From Cell Nutrition, 3rd ed.

• Metabolic shift?

• Glycolysis can be strongly up-regulated to generate more ATP perunit of time, even though the breakdown of glucose is not as efficientthan ATP generated from oxidative phosphorylation

• Amino acids

• Increased utilization of sulfur amino acids for immune proteincomponents

• Gluconeogenesis (amino acids glucose ATP)

Department of Animal Science

Week 3 post-challenge serum data

0

50

100

150

Glu

co

se (

mg

/dL

)

a, b P<0.05

0

50

100

150

200

Insu

lin

(n

g/L

)

PRRSv-

PRRSv+

0.0

0.5

1.0

1.5

2.0

G:I

rati

o

a

b

a

b

Higher degree of insulin

sensitivity in PRRSv infected

pigs

Department of Animal Science

Metabolomic Analysis of Serum using NMR

(IPPA #12-113)

Group 1 and 2 RED BOXES

• LOW GROWTH RATE

Group 3 and 4 BLUE BOXES

• HIGH GROWTH RATE

0 7 14 28 56

Time, d0 7 14 28 56

Time, d

0 7 14 28 56

Time, d

Department of Animal Science

• Poorer growth responding pigs to PRRSv• Higher blood

glycerol, urea, and lactate

• Lower blood glucose, pyruvate and citrate

• Pigs that regulate metabolic shifts (oxidative to glycolytic metabolism) may handle immune challenges better?• This appears to be also

influenced by genetic selection for disease tolerance

Department of Animal Science

Summary

• Understanding the pigs metabolism during an immune challenge(PRRSv) will help us understand how to feed and manage theseanimals• Reduced feed intake and digestibility

• Reduced tissue accretion

• Long lasting impact on feed efficiency

• Glycolytic shift in metabolism may be important

• Can we really feed sick pigs adequately?

• Altered nutrient requirements?

• Key areas of opportunity• Increasing appetite

• Lowering the energetic cost of disease

• Get pigs over the health challenge as fast as possible to minimize thegrowth check

• Compensatory growth???

Department of Animal Science

Acknowledgements• USDA – Animal Health Formula Funds

• National Pork Board• Grant# 12-163

• Iowa Pork Producers Association• Grant# 12-113

• Choice Genetics• Dr. Mark Weaver

• Randy Miller

• Jay Flora

• Drs. Gabler, Burley and Odle laboratory staff and students• Wes Schweer (MS-student apart of Grant# 12-163)