260
fatness from high intake of concentrate diets is associated with increased deposition
of n-6 PUFA. As shown in Table 1, concentrates are rich sources of n-6 PUFA,
mainly due to linoleic acid (C18:2 n-6). The increase in deposition of n-6 PUFA with
supplementation corresponds with the observed increase in n-6/n-3 ratio with supplementation. The higher proportions of n-3 PUFA observed in LD from nonsupplemented goats (T0) agree with the findings of Nuernberg et al. (2005) and
Horcada et al. (2012). The higher proportion of linolenic acid (C18:3 n-3) in nonsupplemented (fed forage only) goats could be due to the low fatty acid concentration
linked to their leanness, as well as due to forage consumption per se. Forages are rich
sources of linolenic acid, a precursor for long chain n-3 PUFA (Daniel et al. 2004;
Diaz et al. 2002). Demirel et al. (2006) found that level of linolenic acid in LD from
lambs fed hay was 3.5 times higher than in those fed concentrate; in the present
study, LD from goats with access to forage had a proportion of linolenic that was
only six time higher than that of goats in ad libitum concentrate intake. To avoid
various lifestyle diseases such as coronary heart disease, diabetes, cancer and atherosclerosis in consumers, the ratio of n-6/n-3 in meat is recommended to be below 4
(Aurousseau et al. 2004; Warren et al. 2008). In the present study, the ratio of n-6/
n-3 in LD from goats on various levels of concentrate supplementation was below 4,
indicating that irrespective of the level of concentrate supplementation, goats produce meat with favourable n-6/n-3 PUFA ratio in the lean.
4.2 Fatty Acid Composition in Minced Meat (MM)
With the exception of the lack of effect on the proportion of palmitic acid, concentrate supplementation affected fatty acid composition in MM in a similar way as in
LD. In addition to intramuscular fat contained in LD, MM contained inter-muscular
and subcutaneous fat depots, which we expected to be affected differently by
concentrate supplementation. Deposition of fat in different depots in meat animals
starts with internal fat, followed by intermuscular, subcutaneous depot and lastly
intramuscular fat (Hausman et al. 2009; Joo et al. 2013). The lack of difference
between MM and LD with respect to the proportion of major fatty acids following
concentrate supplementation can be attributed to the uniqueness of goats in fat
deposition. Unlike cattle and sheep, goats deposit most of their fat internally.
Therefore, increased energy intake from concentrate supplementation will result in
more internal fat than carcass fat in goats (Banskalieva et al. 2000). This means MM
(representing carcass fat) from concentrate-supplemented goats was not significantly different from LD in terms of total fat content. Increased carcass fatness leads
to the increase in total fatty acid concentration. This increase is characterised by
higher concentration of triacylglycerol fatty acids with no change on the concentration of fatty acids in polar lipids (Webb et al. 1998; Juarez et al. 2008).
The observed higher proportion of oleic acid (C18:1 n-9) in MM from
concentrate- fed goats is in accordance with Daniel et al. (2004), but not with
Johnson and McGowan (1998). In addition to being produced de novo through the
D. E. Mushi and L. O. Eik
fatness from high intake of concentrate diets is associated with increased deposition
of n-6 PUFA. As shown in Table 1, concentrates are rich sources of n-6 PUFA,
mainly due to linoleic acid (C18:2 n-6). The increase in deposition of n-6 PUFA with
supplementation corresponds with the observed increase in n-6/n-3 ratio with supplementation. The higher proportions of n-3 PUFA observed in LD from nonsupplemented goats (T0) agree with the findings of Nuernberg et al. (2005) and
Horcada et al. (2012). The higher proportion of linolenic acid (C18:3 n-3) in nonsupplemented (fed forage only) goats could be due to the low fatty acid concentration
linked to their leanness, as well as due to forage consumption per se. Forages are rich
sources of linolenic acid, a precursor for long chain n-3 PUFA (Daniel et al. 2004;
Diaz et al. 2002). Demirel et al. (2006) found that level of linolenic acid in LD from
lambs fed hay was 3.5 times higher than in those fed concentrate; in the present
study, LD from goats with access to forage had a proportion of linolenic that was
only six time higher than that of goats in ad libitum concentrate intake. To avoid
various lifestyle diseases such as coronary heart disease, diabetes, cancer and atherosclerosis in consumers, the ratio of n-6/n-3 in meat is recommended to be below 4
(Aurousseau et al. 2004; Warren et al. 2008). In the present study, the ratio of n-6/
n-3 in LD from goats on various levels of concentrate supplementation was below 4,
indicating that irrespective of the level of concentrate supplementation, goats produce meat with favourable n-6/n-3 PUFA ratio in the lean.
4.2 Fatty Acid Composition in Minced Meat (MM)
With the exception of the lack of effect on the proportion of palmitic acid, concentrate supplementation affected fatty acid composition in MM in a similar way as in
LD. In addition to intramuscular fat contained in LD, MM contained inter-muscular
and subcutaneous fat depots, which we expected to be affected differently by
concentrate supplementation. Deposition of fat in different depots in meat animals
starts with internal fat, followed by intermuscular, subcutaneous depot and lastly
intramuscular fat (Hausman et al. 2009; Joo et al. 2013). The lack of difference
between MM and LD with respect to the proportion of major fatty acids following
concentrate supplementation can be attributed to the uniqueness of goats in fat
deposition. Unlike cattle and sheep, goats deposit most of their fat internally.
Therefore, increased energy intake from concentrate supplementation will result in
more internal fat than carcass fat in goats (Banskalieva et al. 2000). This means MM
(representing carcass fat) from concentrate-supplemented goats was not significantly different from LD in terms of total fat content. Increased carcass fatness leads
to the increase in total fatty acid concentration. This increase is characterised by
higher concentration of triacylglycerol fatty acids with no change on the concentration of fatty acids in polar lipids (Webb et al. 1998; Juarez et al. 2008).
The observed higher proportion of oleic acid (C18:1 n-9) in MM from
concentrate- fed goats is in accordance with Daniel et al. (2004), but not with
Johnson and McGowan (1998). In addition to being produced de novo through the
D. E. Mushi and L. O. Eik