Agriculture Reference
In-Depth Information
18:0
18:1
18:2
18:3
Δ
9
Δ
12
Δ
15
Stearic acid
Oleic acid
Linoleic acid
α
-Linolenic acid
LA
ALA
Δ
6
Δ
6
18:3
γ
-Linolenic acid
GLA
18:4
Stearidonic acid
SDA
Δ
15
Fig. 7.1.
Fatty acid biosynthesis in plants and the new introduced changes to produce stearidonic acid
(C18:4 n-3) and the effects of various desaturases (
6 and
15). (From Ursin, 2003; Whelan, 2009.)
linoleic acid (C18:2) are adequately decreased
(Table 7.6).
Rymer
et al
. (2011) added 45 (grower)
and 50 g SDA oil containing 24% of
stearidonic acid per kg i nisher broiler diet
and compared this with conventional
soybean oil. h e authors did not observe any
signii cant inl uence of SDA oil on feed
intake, weight gain and feed conversion rate
in the animals, but they found some
inl uence on fatty acids in various body fats
(see Chapter 10). Similar results are
described by Bernal-Santos
et al
. (2010) in
lactating cows after duodenal infusion of
SDA soybean oil; by Kitessa and Young
(2011) after feeding of ruminally protected
SDA oil to dairy cows; and by Mejia
et al
.
(2010) in laying hens. Such long-chain
omega-3 polyunsaturated fatty acids may
also be important for i sh nutrition and to
replace i sh oils in human nutrition as a
precursor of eicosapentaenoic acid (EPA,
C20:5 n-3) and docosahexaenoic acid (DHA,
C22:6 n-3; Cahoon
et al
., 2007).
Amaro
et al
. (2012) tested the inl uence
of increasing levels of stearidonic acid (up to
50 mg/l incubation media) on methane
production in a rumen
in vitro
system. h e
SDA supplementation was not associated
with a reduction in methanogenesis. Higher
levels or an alternative form might be
needed.
Apart from stearidonic acid, the ability to
genetically engineer plants has facilitated
the generation of oilseeds also synthesizing
fatty acids that are seldom in oils or are
non-native (Napier, 2007), but which are
used for various technical purposes. For
example, Böhme
et al
. (2007) tested oil from
rapeseed in which the acyl-thioesterase gene
of
Cuphea lanceolata
was inserted. h e
portion of mid-chain fatty acids (C
12
-C
16
)
increased from 5.2 to 33.3% in the transgenic
rape; those of oleic acid reduced from 68.6 to
42.6%. h e glucosinolate content increases
from 12.4 in the parenteral plant to 19.0
μmol/g DM in the GM plant and requires a
critical analysis (Böhme
et al
., 2007).
Carbohydrates in plants may also be a
subject of genetic modii cation; for example,
inulin, as polymers of fructans, was intended
for use as a prebiotic functional food in
human nutrition. Heyer
et al
. (1999) and
Sevenier
et al
. (1998) introduced genes of
globe artichoke (
Cynara scolymus
) into
potatoes or sugarbeets and found an ability
to synthesize high molecular weight fructan
as inulin. h e inulin concentration in the dry
matter of the transgenic tubers amounted to
about 5% (Hellwege
et al
., 2000), and starch
Table 7.6
. Fatty acid composition of soybean oil
and 'SDA oil' (% of oil) from soybeans used in the
study by Rymer
et al
. (2011).
Fatty acids
Soybean oil
SDA soybean oil
C16:0
7.3
8.4
C18:0
3.1
3.0
C18:1
14.0
9.8
C18:2
34.0
12.4
C18:3
5.0
12.3
C18:4 (SDA)
0
24.1
