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


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


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


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)


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?


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


• 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


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)


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


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


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


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


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


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


AD

FI (k

g/d

)

-32%

* * * *

* * * *

-50%


*

*

* *

Weekly Performance

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7


Ga

in:F

ee

d

PRRSv-

PRRSv+

-27%

* P<0.05 within week

-25%


• So what is the impact of PRRSv on body

composition and tissue accretion?


DXA = Dual X-Ray Absorptiometry

Predicts:

Total mass (g)

Lean (g)

Fat (g and %)

Bone mineral

density & content


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


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)


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


• So what is the impact on total tract digestibility?


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)


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


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


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


• So what is the impact on carcass performance and

the bottom line?


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


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)


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


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)

http://upload.wikimedia.org/wikipedia/commons/7/74/CellRespiration.svg


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


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


• 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


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???


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)

dr. nick gabler - the impact of prrsv on feed efficiency, digestibility and tissue accretion in...

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