It is generally accepted that insufficient feed intake by
sows during lactation is a serious problem in the swine
industry. In past years, there was an increasing burden
on sow milk yield due to genetic selection for large
litter sizes (Auldist et al. 1998). Meantime, genetic
selection for high growth and lean rate resulted in a
lower appetite and fat reserves in sows (Kerr &
Cameron 1996). Therefore, feed intake of sows during
lactation was frequently inadequate to meet the needs
of maintenance, milk production and body growth
(Noblet et al. 1990). Insufficient feed intake could
produce a series of reproductive disorders, including
decreasing ovulation and pregnancy rates, increasing
the incidence of anoestrus, embryo mortality and
weight loss during lactation, and extending weaningestrus
interval (Eissen et al. 2000). Additionally, insufficient
feed intake was more common in primiparous
sows, and resulted in a negative effect on sow performance
and reduced subsequent productivity (Koketsu
et al. 1996; Eissen et al. 2003; Sulabo et al. 2010).
Flavor and sodium butyrate have been reported to
improve feed intake and growth performance of
weaning or growing pigs (McLaughlin et al. 1983;
Torrallardona et al. 2000; Le Gall et al. 2009), but little
was known on sows. Therefore, it is interesting to
address the question whether flavor or sodium
butyrate could improve sow feed intake or not.
Weaning is a stressful event for piglets; the changes
in intestinal morphology and function induced by
lower feed intake is the most important reason for
weaning stress (Spreeuwenberg et al. 2001). Thus, it is
noteworthy to enhance pig feed intake in the first few
days after weaning. Previous studies found that prenatal
and postnatal flavor learning could reduce stressrelated
effects, influence offspring acceptance and
stimulate similarly flavored food intake (Mennella
et al. 2001; Oostindjer et al. 2010). Indeed, it has been
recognized that maternal flavor intake would transfer
to the fetus via amniotic fluid and thus enhanced the
fetal cognitive acceptance for this flavor (Mennella