Transcript Weiguo Cai, David Casey & Jack Dekkers

Selection Lines for
Residual Feed Intake (RFI)
in Yorkshire Swine
Weiguo Cai1, David Casey2, Jack Dekkers1
1Department
of Animal Science, Iowa State University, Ames, IA 50011 and
2Pig Improvement Company, Franklin, KY 42134
Measures of
Feed Efficiency
FCR = Feed/gain
FE = Gain/Feed
Residual Feed Intake = (Observed FI) – (Expected FI given ADG, BF, BW)
(Koch et al., 1963)
= FI – b1 ADG – b2 BF – b3 BW.75
Observed FI
RFI
Predicted FI
Factors contributing to RFI
• Physical activity
• Body temp. regulation
• Basal metabolic rate
• Digestibility
• Energetic efficiency
• Immune response
• Food wastage
• Measurement error
Yorkshire RFI
Selection Experiment
Objectives
• Develop lines that differ in FI but have similar ADG, BF
• Estimate genetic parameters
• Evaluate direct and correlated responses to selection
• Develop a resource population to
• study the biological / physiological basis of feed intake / efficiency
• develop selection tools for feed intake / efficiency
Outline

Feed intake recording in pigs

Design of selection experiment

Results: Direct and correlated responses
Estimates of genetic parameters

Ongoing and future work
Recording individual
feed intake in pigs
Electronic Feeder
FIRE© Osborne Inc.
Commercial Feeder
Feed intake data
Extensive edit procedures
for feed intake data
Identify errors in visits (16 criteria)
Create graphs (each pig)
Remove unwanted information
Fill-in missing daily FI
Calculate average daily FI
Developed by David Casey
Casey, Stern, Dekkers. 2005.
J. Anim. Sci. 83:969–982.
unexplained transponder
zero tag consumption
outliers from graphs
etc.
Design of RFI
selection experiment
Generation 0
Low RFI line
select for
RFI
reduce FI
keep adg, bf ~ constant
Control line
Generation 1
Generation 2
Generation 3
Generation 4
Random
selection
Design of RFI
selection experiment
Select Line
RFI
Generation 1 parity 1
selection
Control Line
Generation 2
parity 1
Generation 2
parity 2
Random selection
90 boars on FIRE©
Sibs of
Selected boars
90 gilts on FIRE©
RFI EBV
Select ~12 boars
~70 gilts
Traits measured
− from ~40 to ~115 kg
 Electronically measured feed intake (FIRE©, Osborne Inc.)
 1st parity select boars
 2nd parity select gilts
 Ultrasound scan
– on-test
– mid-test
– off-test
 Body weight – weekly
Average daily gain
(ADG)

Weigh pigs weekly

Linear regression of
weight on day:  ADG
(kg/day)
Ultrasound Scan

Backfat (BF) -10th rib

Loin muscle area (LMA)

Intramuscular Fat (IMF)
Summary of data
across 4 gener. in select line
Traits
N
Mean
Phen.Std
RFI (kg/d)
836
0
0.11
ADFI (kg/d)
836
1.99
0.16
ADG (kg/d)
836
0.77
0.08
BF (mm)
836
7.95
2.90
LMA (cm2)
836
26.28
4.04
IMF (%)
565
1.74
0.39
Note: Phen.Std excludes all fixed effects and pen(group) effect
Var(RFI)
Var(FI)
=0.46
RFI EBV model
(ASREML)
FI = group + sex+ pen(group) +
b1*(onwt*gen) + b2*(onage*gen) + b3*(offwt*gen) +
b4*(ADG*gen) + b5*(BF*gen) + BVRFI + e
ADG and BF pre-adjusted for onwt, onage, offwt
Fixed: group and sex
Random: pen (group)
Note: Metabolic weight not included
Selection response
for RFI and FI
1.1 sp
1.1 sp
Correlated responses
for ADG and BF
0.3 sp
0.3 sp
Correlated responses
for LMA and IMF
0.1 sp
0.1 sp
Heritabilities and correlations
Based on ASREML 2-trait analysis
RFI
RFI
FI
ADG
BF
LMA
IMF
0.33
FI
ADG
BF
0.40
0.33
0.61
LMA
0.62
IMF
Heritabilities (on diagonal)
0.53
genetic (below diagonal)
phenotypic (above diagonal)
Heritabilities and correlations
Based on ASREML 2-trait analysis
RFI
RFI
FI
ADG
BF
LMA
IMF
0.33
0.51
-0.01
-0.01
-0.10
0.04
0.40
0.65
0.44
-0.03
0.10
0.33
0.29
0.11
0.18
0.61
-0.05
0.04
0.62
0.07
FI
ADG
BF
LMA
IMF
Heritabilities (on diagonal)
0.53
genetic (below diagonal)
phenotypic (above diagonal)
Heritabilities and correlations
Based on ASREML 2-trait analysis
RFI
FI
ADG
BF
LMA
IMF
RFI
0.33
0.51
-0.01
-0.01
-0.10
0.04
FI
0.71
0.40
0.65
0.44
-0.03
0.10
ADG
0.15
0.74
0.33
0.29
0.11
0.18
BF
-0.01
0.55
0.40
0.61
-0.05
0.04
LMA
-0.26
-0.10
0.19
-0.05
0.62
0.07
IMF
0.15
0.23
0.27
-0.06
0.26
0.53
Heritabilities (on diagonal)
genetic (below diagonal)
phenotypic (above diagonal)
Design of direct
line comparison
Generation 3
Parity 2
Selection line
n=50
Control line
n=38
88 gilts on FIRE
identify extremes at 70 kg
(gene expression)
Estimates of line
differences
Trait
Line difference (select-control)
estimated based on
EBV
in selection line
Direct
comparison
RFI, g/d
-124
-93***
FI, g/d
-175
-123***
ADG, g/d
-24
-22NS
BF, mm
-0.77
0.063 NS
*** significant at P<.01, NS Not significant at P<.10
Summary

46% of variation in FI is not related to ADG and BF
= RFI

RFI has substantial heritability (0.33)

4 generations of selection for RFI has resulted in
significant change in RFI (93-124 g/d)

RFI selection has slightly reduced ADG and BF
Integration of Functional Genomics and Quantitative
Genetics to Improve Feed Efficiency in Pigs
Dekkers, Tuggle, Anderson, Nettleton, Honavar
Iowa State University
Rekaya, Barb, Hausman
University of Georgia and USDA-ARS-RARC
NRI Grant no. 2005-35604-15618
Yorkshire selection & control lines
for Residual Feed Intake
Gene expression
studies
High RFI
gilts
Control line
Low RFI
gilts
Select line
4
Restr.
feeding
SR
4
Limited
numbers
Ad
Libitum
SA
Liver
Source: http://www.affymetrix.com
4
Restr.
feeding
CR
~70 kg
Image from Hybridized GeneChip
4
Ad
Libitum
CA
Fat
RNA
Gene Expression
Microarray
Measure the level of expression of
>20,000 probes for genes across
genome
Biological basis of
differences in RFI
Residual Feed Intake = (Observed FI) – (Expected FI given ADG, BF, BW)
(Koch et al., 1963)
Observed FI
RFI
Factors contributing to RFI
Predicted FI
• Physical activity
• Body temp. regulation
• Basal metabolic rate
• Digestibility
• Energetic efficiency
• Immune response
• Food wastage
Richardson and Herd 2004
• Measurement error
Figure 1. Residual Feed Intake (RFI)
New grant funded by National Pork Board
and Iowa Pork Producers Association
Acknowledgements
Weiguo Cai, David Casey
John Newton and personnel at ISU Bilsland farm
Ann Crock
Jay Lampe
Napapan Piyasatian
Jeremy Burkett
Sender Lkhagvadorj
Yangfang Wang
Jennifer Kerkman
Bryce Martin
Ryan Voyles
Nick Berry
Long Qu
Dan Nettleton
Matt Wolfe
Benny Mote
Doug Newcom
Tom Baas
Chris Tuggle
Lloyd Anderson
PIC/Genus for providing FIRE© feeders
ISU Center for Integrated Animal Genomics
Monsanto Choice Genetics
USDA-CSREES NRI Grant no. 2005-35604-15618