The objective of this study was to infer
(co)variance components for piglet survival at birth in
purebred and crossbred pigs. Data were from 13,643
(1,213 litters) crossbred and 30,919 (3,162 litters) pure-
bred pigs, produced by mating the same 168 purebred
boars to 460 Large White-derived crossbred females
and 1,413 purebred sows, respectively. The outcome
variable was piglet survival at birth as a binary trait.
A Bayesian bivariate threshold model was implemented
via Gibbs sampling. Flat priors were assigned to the
effects of sex, parity of the dam, litter size, and year-
month of birth. Gaussian priors were assigned to litter,
dam, and sire effects. Marginal posterior means (SD)
of the sire and dam variances for liability of piglet sur-
vival in purebred were 0.018 (0.008) and 0.077 (0.020),
respectively. For crossbred, sire and dam variance es-
timates were 0.030 (0.018) and 0.120 (0.034), respec-
tively. The posterior means (SD) of the heritability of
liability of survival in purebred and crossbred and of
the genetic correlation between these traits were 0.049
(0.023), 0.091 (0.054), and 0.248 (0.336), respectively.
The greatest 95% confidence region (−0.406, 0.821) for
the genetic correlation between purebred and crossbred
liabilities of piglet survival included zero. Results sug-
gest that the expected genetic progress for piglet sur-
vival in crossbreds when selection is based on purebred
information may be nil.
Bayesian analysis, genotype × environment interaction, piglet survival, threshold model
©2010 American Society of Animal Science. All rights reserved.
J. Anim. Sci. 2010. 88:481–490
Crossbreeding of swine is widely accepted as an ef-
fective commercial production practice (Merks, 1988).
Structured crossbreeding can exploit additive and non-
additive genetic effects to advantage (Siegel, 1988). Al-
though economic returns in pig production derive main-
ly from crossbred performance, selection of prospective
parents is usually based on purebred performance.
The genetic correlation between purebred and cross-
bred performance provides an indicator for evaluating
the effectiveness of reciprocal recurrent selection (Com-
stock et al., 1949), combined purebred and crossbred se-
lection (Wei and van der Werf, 1994), and of the use of
data recorded only in crossbreds for evaluation of pure-
breds (Lutaaya et al., 2001). Often, estimates of such
genetic correlations for production traits have been less
than unity (Merks, 1988; Wei and van der Werf, 1995)
indicating that selection of parents in one type of mat-
ing system may not optimize progeny performance in
another type of system (Mulder and Bijma, 2005).