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The fatty acid (FA) composition in the intramuscular fat (IMF) of the musculus longissimus dorsi (MLD) of Ile de France purebred lambs in two different production systems in Slovakia was evaluated using gas chromatography. In the first production system, lambs and ewes were assigned to pasture without access to concentrates (P). In the second system, lambs and ewes were confined indoors with hay/silage and access to concentrates (S). An analysis of variance with the following factors was employed: production system, sex, and production system–sex interactions. The proportions of arachidonic, eicosapentaeonic, docosapentaeonic, and docosahexaenoic FAs, i.e. long-chain polyunsaturated FA (PUFA), were significantly higher in P lambs (1.83, 0.82, 0.92, 0.29 g 100 g -1 FAME, respectively) than in S lambs (0.45, 0.14, 0.30, 0.09 g 100 g -1 FAME, respectively). The proportions of conjugated linoleic acid (CLA), n-6 PUFA, n-3 PUFA, and essential FA (linoleic and α -linolenic) were also significantly higher in P lambs (2.10, 8.50, 4.55, and 8.80 g 100 g -1 FAME, respectively) than in S lambs (0.65, 3.27, 1.50, and 3.64 g 100 g -1 FAME, respectively). The proportions of palmitic acid and myristic acid as important individual saturated FAs (SFA) were significantly higher in S lambs (28.51 and 8.30 g 100 g -1 FAME, respectively) than in P lambs (21.80 and 5.63 g 100 g -1 FAME, respectively). The proportion of all SFAs was also significantly higher in S lambs (57.87 g 100 g -1 FAME) than in P lambs (48.70 g 100 g -1 FAME). From a nutrition and human health point of view (i.e. higher proportions of PUFA, CLA, and essential FAs and lower proportions of SFAs), meat from P lambs was found to be more favourable and would be more highly recommended for consumption. [ABSTRACT FROM AUTHOR]

Abstract: A generally known problem of GC separation of trans-7;cis-9; cis-9,trans-11; and trans-8,cis-10 CLA (conjugated linoleic acid) isomers was studied by GC–MS on 100m capillary column coated with cyanopropyl silicone phase at isothermal column temperatures in a range of 140–170°C. The resolution of these CLA isomers obtained at given conditions was not high enough for direct quantitative analysis, but it was, however, sufficient for the determination of their peak areas by commercial deconvolution software. Resolution factors of overlapped CLA isomers determined by the separation of a model CLA mixture prepared by mixing of a commercial CLA mixture and CLA isomer fraction obtained by the HPLC semi-preparative separation of milk fatty acids methyl esters were used to validate the deconvolution procedure. Developed deconvolution procedure allowed the determination of the content of studied CLA isomers in ewes’ and cows’ milk samples, where dominant isomer cis-9,trans-11 is eluted between two small isomers trans-7,cis-9 and trans-8,cis-10 (in the ratio up to 1:100). [Copyright &y& Elsevier]

A generally known problem of gas chromatographic (GC) separation of trans-7,cis -9, cis-9,trans-11, and trans-8,cis-10 conjugated linoleic acid (CLA) isomers was studied by GC on a 200 m capillary column coated with a cyanopropyl silicone phase at 130 °C. The resolution of these CLA isomers obtained at given experimental conditions was not high enough for direct quantitative analysis but it was, however, sufficient for the determination of their peak areas by a commercial deconvolution software. Relative retentions and resolution factors of CLA isomers with overlapped peaks determined by the separation of a commercial CLA standard mixture as well as CLA isomer fractions obtained by the HPLC semi-preparation of ewe milk were used as input data in the deconvolution procedure. The milk of pasture-fed ewes with higher cis-9,trans-11 isomer contents showed higher contents of trans-7,cis-9 as well as trans-8,cis-10 CLA isomers in comparison with milk fat of total mixed rations (TMR)-fed ewes. For cow milk samples showing lower CLA contents, no such trends were evident. [ABSTRACT FROM AUTHOR]