Agriculture Reference
In-Depth Information
al.
, 2003; Farmer
et al.
, 2010). On the other hand, a high level of fish oil supplementation
may not improve piglet growth. Danielsen and Lauridsen (2001) reported a significantly
smaller litter size at weaning, as well as a decreased milk production when providing
10% fish oil in the diet of lactating sows. Evidence suggests that dietary supplementation
with n-3 FA and n-6 FA is effective in increasing their availability in the porcine fetus.
A high n-6/n-3 ratio is considered to be a critical factor for both insulin resistance and
atherosclerosis (Papadopoulos
et al.
, 2009). Alterations of the ratio of n-6 and n-3 PUFA
in the diet of lactating sows may influence the immune components from sows, including
immunoglobulin and cytokines, as well as the immune status of piglets. Yao
et al.
(2012)
reported that an n-6/n-3 ratio of 9:1 in sow diets increased the IgG concentration in
colostrum and IgM concentration in milk compared with ratios of 3:1 and 13:1.
16.4
Conjugated linoleic acid
Fatty acids with conjugated double bonds occur naturally in edible fats derived from
ruminants, for example, in milk fat and beef tallow (Pariza
et al.
, 2001). Conjugated
linoleic acid (CLA) is the collective name for a group of geometric and positional isomers
of LA in which the double bonds are separated by a single carbon-carbon bond instead
of a methylene group. The two isomers most studied for their biological effects are
cis
-9,
trans
-11 CLA (c9, t11), the predominant isomer produced in ruminants, and
trans
-10,
cis
-12 CLA (t10, c12). Both isomers have been used in experimental studies, and represent
the most widely investigated CLA isomers. CLA were shown to have many favourable
biological effects, as reviewed by Pariza
et al.
(2001). he
cis
-9,
trans
-11 isomer is mainly
responsible for anti-carcinogenic effects, but the
trans
-10,
cis
-12 isomer reduces body fat
and is referred to as the most effective isomer affecting blood lipids (Rossi
et al.
, 2010).
Consumption of CLA during lactation was shown to increase the concentration of CLA in
sow milk (Schmid
et al.
, 2008). Dietary CLA supplementation during lactation also resulted
in enrichment of colostrum and milk with CLA, therefore allowing suckling piglets access
to CLA isomers (Bee, 2000a). It therefore appears that CLA could be transferred from the
dam to her offspring through milk. In addition, the ability of CLA to stimulate immune
function was demonstrated in sucking piglets whose dams were fed 0.5% CLA during late
pregnancy and lactation (Bontempo
et al.
, 2004; Corino
et al.
, 2009).
16.4.1
Effects of conjugated linoleic acid on immune status of sows and
piglets
Previous studies reported that CLA have immunomodulating effects in several
experimental models (Bassaganya-Riera
et al.
, 2001; Corino
et al.
, 2002; Whigham
et
al.
, 2001). In swine, dietary CLA was reported to increase immunoglobulin production
(Corino
et al.
, 2009; Moraes
et al.
, 2012), and the anti-inflammatory properties of CLA
were evidenced by a reduction in pro-inflammatory cytokines in response to an immune
challenge (Lai
et al.
, 2005). CLA were also reported to reduce the catabolic response
induced by immune stimulation without adversely affecting immune function. This
catabolic response is mediated by cytokines and regulated by PGE2 synthesis (Miller
et al.
,
1994). Reducing the immune response may therefore provide more energy for anabolic
