M. Dufrasne 1,2, V. Jaspart 3, J. Wavreille 4 et N. Gengler 1

1 University of Liège, Gembloux Agro Bio-Tech, Animal Science Unit - Gembloux 2 F.R.I.A. - Brussels

3 Walloon Pig Breeders Association (AWEP) - Ciney 4 Walloon Agricultural Research Centre (CRA-W) - Gembloux

ADVANCED GENETIC MODELS FOR PIÉTRAIN BOARS INVOLVED IN CROSSBREEDING IN THE WALLOON REGION USING TEST STATION

AND ON-FARM PHENOTYPIC AND GENOMIC DATA 

Contact: marie.dufrasne@ulg.ac.be

RESEARCH SUPPORTED BY THE WALLOON REGION OF BELGIUM

CONTEXT New genetic evaluation program for Walloon Piétrain boars tested in test station

Test station progeny test for production traits (growth, carcass quality traits and feed intake) On-farm performance test for traits recorded on live pigs (weight and carcass quality traits)

Crossbred progeny from Piétrain sires and Landrace K+ dams

OBJECTIVETo develop genetic evaluation models combining test station and on-farm data to estimate the genetic values of Piétrain boars for

crossbred performances

Growth

Data: 17 483 live weight from 2 076 crossbred progeny of Piétrain boars recorded at the test station between 50 and 210 days of age 54 068 live weight from 50 824 purebred and crossbred pigs recorded on-farm between 175 and 250 days of age Breed types: purebred Piétrain and Landrace (on-farm); crossbred Piétrain X Landrace (test station and on-farm) Data recorded on females, entire and castrated males Data standardized for each day of age and pre-adjusted at 210 days to take into account variance heterogeneity

Model (Dufrasne et al., 2011): Bi-trait animal model with random regressions using linear splines (knots at 50, 100, 175 and 210 days for test station weight; knots at 175, 210 and 250 days for on-farm weight):

y = Xb + Q (Za + Zp) + ey = vector of observations (test station and on-farm weight) e = vector of random residual

b = vector of fixed effects (sex, contemporary group (CG), heterosis) Q = matrix of linear spline coefficients

a = vector of random additive effect X, Z = incidence matrix

p = vector of random permanent environment effect

Carcass quality traits

Data: Three traits (backfat thickness (BFa), loin muscle depth (LMD) and meat percentage (%Ma)) recorded on live animals in test station for progeny of tested boars, and

on-farm for performance tested pigs (37 824 animal recorded for each traits) Four traits (backfat thisckness (BFb), meat percentage (%Mb), carcass weight (CW) and conformation index (CONF)) recorded on carcass only for crossbred

progeny of boars tested in test station (1 980 animals recorded for each trait) Breed types: purebred Piétrain and Landrace (on-farm); crossbred Piétrain X Landrace (test station and on-farm) Data recorded on females, entire and castrated males Linear pre-adjustment of data at 200 days of age

Model: Multitrait animal model: y = Xb + Za + e

y = vector of observations (BFa, LMD, %Ma, BFb; %Mb, CW and CONF)

b = vector of fixed effects (sex, CG and heterosis for live traits; sex, slaughtdate and heterosis for carcass traits)

Feed intake

Data: 1 914 records of estimated individual feed intake (EFI) only for crossbred progeny of boars tested in test station Data recorded on female and castrated males Individualization of records by linear regression on average daily gain (ADG) between 100 and 210 days and on live weight at 100 days (LW100), both expressed

in breeding values

Model: Unitrait animal model y = Xb +Za + ey = vector of observations (EFI)

b = vector of fixed effects (sex and pen; ADG and LW100 as linear covariables)

RESULTS For 75 Piétrain boars already progeny tested until now, breeding values (EBV) were estimated using the data and the models described above. For the moment Walloon pig breeders receive EBV and associated reliabilities for the following traits to base their selection decisions on:

UNDER DEVELOPMENT Global index combining different traits Further enhanced models that will allow also estimation of non-additive and crossbreeding effects Genomic selection of Walloon Piétrain boars using Single Nucleotid Polymorphism (SNP) genotypes to estimate additive, non-additive and

crossbreeding effects

• ADG between 100 and 210 days • Live weight at 210 days• Backfat thickness • Loin Muscle depth• Carcass weight • Meat percentage • Conformation Index • Feed conversion ratio