Author:
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Henriquez Rodriguez, Eliana; Pena i Subirà, Ramona Natacha; Seradj, Ahmad Reza; Fraile Sauce, Lorenzo José; Christou, Paul; Tor i Naudí, Marc; Estany Illa, Joan
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Notes:
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Nutritional and genetic strategies are
needed to enhance intramuscular fat (IMF) and MUFA
content without altering carcass leanness. Dietary
vitamin A restriction has been suggested to specifically
promote IMF, whereas a polymorphism of the
stearoyl-CoA desaturase (SCD) gene has shown to
specifically increase MUFA. The purpose of this
study was to investigate the combined effects of provitamin
A (PVA) carotenoid intake and SCD genotype
(AY487830:g.2228T>C) on hepatic retinoid content
and on the liver, muscle (LM and gluteus medius
[GM]), and subcutaneous fat (SF) content and fatty
acid composition. Following a split-plot design, 32
castrated Duroc pigs, half of each of the 2 homozygous
SCD genotypes (CC and TT), were subjected from 165
to 195 d of age to 2 finishing diets differing in the PVA
carotenoid content (an enriched-carotene diet [C+] and
a control diet [C-]). Both diets were identical except for
the corn line used in the feed. The C+ was formulated
with 20% of a carotenoid-fortified corn (M37W-Ph3)
whereas the C- instead used 20% of its near isogenic
M37W line, which did not contain PVA carotenoids.
No vitamin A was added to the diets. The C- was estimated to provide, at most, 1,300 IU of vitamin A/kg
and the C+ to supply an extra amount of at least 800 IU
vitamin A/kg. Compared with the pigs fed the C-, pigs
fed with C+ had 3-fold more retinoic acid (P < 0.01)
and 4-fold more SCD gene expression in the liver (P =
0.06). The diet did not affect performance traits and
backfat thickness, but pigs fed the C+ had less fat (4.0
vs. 5.0%; P = 0.07) and MUFA (18.3 vs. 22.5%; P =
0.01) in the liver, less IMF (5.4 vs. 8.3%; P = 0.04)
in the GM, and more fat content (90.4 vs. 87.9%; P =
0.09) and MUFA (48.0 vs. 46.6%; P = 0.04) in SF. The
TT genotype at the SCD gene increased MUFA (P <
0.05) in all tissues (21.4 vs. 19.5% in the liver, 55.0 vs.
53.1% in the LM, 53.9 vs. 51.7% in the GM, and 48.0
vs. 46.7% in SF for TT and CC genotypes, respectively).
Liver fat and MUFA content nonlinearly declined
with liver all-trans retinoic acid, indicating a saturation
point at relatively low all-trans retinoic acid content.
The results obtained provide evidence for a complementary
role between dietary PVA and SCD genotype,
in the sense that the TT pigs fed with a low-PVA diet
are expected to show higher and more monounsaturated
IMF without increasing total fat content. |