This study investigated the impact of feeding levels in late gestation on
apparent total tract digestibility (ATTD) of gross energy (GE), nutrients
and concentrations of plasma metabolites in transition sows. We hypothesized
that nutrient digestibility decline and concentrations of plasma
metabolites increase with increasing feeding levels. Forty-eight sows
were assigned to six feeding levels (1.8, 2.4, 3.1, 3.7, 4.3 and 5.0 kg/
d) from day 108 of gestation until farrowing. Faecal samples were collected
on day 114 of gestation, whereas plasma samples were collected
at farrowing. Klason lignin measured as acid insoluble residues in the
feed ingredients was used as an internal marker to estimate ATTD of
GE and nutrients. Data were analysed using general linear mixed model
by including feeding levels and parity as the fixed effects and sow as the
random effect. Plasma concentrations of urea (P0.001) and butyrate (P< 0.001) increased, whereas that of non-esterified
fatty acids (Plevel. The ATTD of GE (Psimilar trends, in which ATTD were greatest at 1.8 and 2.4 kg/d, intermediate
at 3.1 kg/d and lowest at ≥ 3.7 kg/d for both parameters. The
ATTD of non-starch polysaccharides (NSP) was greatest at 2.4 and 3.1
kg/d, intermediate at 3.7 and 4.3 kg/d and lowest at 5.0 kg/d (P
0.001). The ATTD of GE, fat and NSP were greater in sows than in gilts
(Pand urea increased with increasing feeding level, indicating increased
fermentation and protein oxidation, whereas the decreased concentration
of non-esterified fatty acids with increasing feeding level implied
a reduced body reserve mobilization. Increased feeding level also
decreased the ATTD of GE, protein and NSP but to different extents.