252
Fatty acid methyl esters were separated in a Thermo Finnigan Focus GC
equipped with automatic injector, Restek capillary column (Rt – 2560; 0.25 mm
internal diameter, 100 m long) and flame ionisation detector. Samples were
injected in a split mode (1:40). The carrier gas was helium (He), which flowed at
a pressure of 2.7 bars. Oven temperature programming was 70 °C for 2 min, 70
to 150 °C for 4 min, 150 °C for 34 min, 150 to 230 °C for 57 min and a final
temperature of 230 °C for 10 min. The injection temperature was 230 °C, and the
detection temperature was 255 °C. The identification of individual FAME in the
samples was achieved by matching the retention time of the unknown FAME
with that of known FAME in the standard mixture (FAME mix, 37 components,
Supelco™). Fatty acid composition in the samples was calculated as the peak
area percentage for each fatty acid, including unidentified fatty acids. Integration
calibration software (Chromeleon, V6.7) connected to the chromatograph, which
converts relative peak areas into weight percentages, was used for these
calculations.
2.5 Physical and Chemical Compositions of Dietary Feeds
The grass hay consisted of Brachiaria spp. (70%) and Bothriochloa spp. (30%).
Concentrate supplement was made of 28% sunflower seed cake, 70% maize bran,
1.3% lime, 0.2% salt and 0.5% mineral mix, with crude protein of 16.2% and estimated metabolisable energy of 13.4 MJ. Chemical and fibre compositions of both
the grass hay and concentrate diet are reported in Table 1. Fatty acid composition of
the concentrate diet is also indicated in Table 1.
2.6 Statistical Analysis
Experimental data were analysed using the general linear model (GLM) procedure
of SAS (2001). Dietary treatments were considered as fixed effects and residual as
random effects. Each individual animal served as an experimental unit for all fatty
acids assessed. Due to small variation in the weight of animals within treatments,
fatty acid composition was corrected for animal weight difference by using weight
as a covariate in the GLM. In all analyses, when least square means were significant by ANOVA at P < 0.05, they were separated by the probability of difference
(PDIFF) option of SAS.
In order to determine the distribution of fatty acids in different fat depots (LD,
MM and OF), principal component analysis (PCA) was carried out on fatty acid
compositions of the three depots using the Unscrambler version 9.2 (CAMO
Process AS, Oslo, Norway) software. Full cross-validation method was
employed in PCA.
D. E. Mushi and L. O. Eik
Fatty acid methyl esters were separated in a Thermo Finnigan Focus GC
equipped with automatic injector, Restek capillary column (Rt – 2560; 0.25 mm
internal diameter, 100 m long) and flame ionisation detector. Samples were
injected in a split mode (1:40). The carrier gas was helium (He), which flowed at
a pressure of 2.7 bars. Oven temperature programming was 70 °C for 2 min, 70
to 150 °C for 4 min, 150 °C for 34 min, 150 to 230 °C for 57 min and a final
temperature of 230 °C for 10 min. The injection temperature was 230 °C, and the
detection temperature was 255 °C. The identification of individual FAME in the
samples was achieved by matching the retention time of the unknown FAME
with that of known FAME in the standard mixture (FAME mix, 37 components,
Supelco™). Fatty acid composition in the samples was calculated as the peak
area percentage for each fatty acid, including unidentified fatty acids. Integration
calibration software (Chromeleon, V6.7) connected to the chromatograph, which
converts relative peak areas into weight percentages, was used for these
calculations.
2.5 Physical and Chemical Compositions of Dietary Feeds
The grass hay consisted of Brachiaria spp. (70%) and Bothriochloa spp. (30%).
Concentrate supplement was made of 28% sunflower seed cake, 70% maize bran,
1.3% lime, 0.2% salt and 0.5% mineral mix, with crude protein of 16.2% and estimated metabolisable energy of 13.4 MJ. Chemical and fibre compositions of both
the grass hay and concentrate diet are reported in Table 1. Fatty acid composition of
the concentrate diet is also indicated in Table 1.
2.6 Statistical Analysis
Experimental data were analysed using the general linear model (GLM) procedure
of SAS (2001). Dietary treatments were considered as fixed effects and residual as
random effects. Each individual animal served as an experimental unit for all fatty
acids assessed. Due to small variation in the weight of animals within treatments,
fatty acid composition was corrected for animal weight difference by using weight
as a covariate in the GLM. In all analyses, when least square means were significant by ANOVA at P < 0.05, they were separated by the probability of difference
(PDIFF) option of SAS.
In order to determine the distribution of fatty acids in different fat depots (LD,
MM and OF), principal component analysis (PCA) was carried out on fatty acid
compositions of the three depots using the Unscrambler version 9.2 (CAMO
Process AS, Oslo, Norway) software. Full cross-validation method was
employed in PCA.
D. E. Mushi and L. O. Eik