the present study. Teye (2009) described differences in fatty acid
compositions as an age or weight effect in his work. Only the
proportion of SFA was significantly different between breeds
after adjusting for NL content, that is, HS had significantly lower
SFA than LR and DU (Table 1). The significant increase of
MUFA with age seemed to be in inverse proportion to the significant
decrease of PUFA (Table 1). The decreasing proportion
of PUFA with age potentially offset some of the contribution
by MUFA to unsaturation.
Fiego and others(2010) did not adjust for NL content, but
observed the same evolution pattern of NL fatty acid classes as
in the present study. Fiego and others (2010) observed a slight
but not statistically significant increase in IMF with age, thus it
is reasonable to assume that the observed changes were mostly
age-related. Conversely, Yang and others (2010) did not find significant
differences in fatty acid class profiles among pigs slaughtered
at 6 or 9 mo. Significant influences have been reported of the cross or breed of pig on the fatty acid class profiles of
lipid fractions (Andres and others 2001; Armero and others 2002;
Zhang and others 2009). However, none of these studies separated
the influence of adipogenic capacity from other intrinsic breed
effects.
Hampshire and DU actually had a higher proportion of
MUFA than LR (Table 1), but the statistical analysis revealed
that the higher level in DU was explained by higher NL content.
The difference in MUFA proportion between HS and LR
seemed to be a function of the low saturated fat level of HS. Duroc
actually had lower PUFA levels than LR and HS (Table 1), but
as for MUFA, this was due to the adipogenic capacity of DU.
Zhang and others (2009) found the NL content in Hampshire and
Landrace to be similar, and significantly lower than in Duroc, as
in our work. However, the breed differences in SFA, MUFA,
and PUFA proportions reported by Zhang and others(2009)
were not seen in our data (Table 1).