Chemical composition of diets and protein and fat contents of the animals’ body
were determined using standard methods [AOAC 1995]. Chromium oxide in the diets
and faeces was determined according to Fenton and Fenton [1979]. The FA profile was
established in homogenized samples with methyl esters method [Folch et al. 1957].
Fatty acids methyl esters were separated by gas chromatography on GC-2010 AF
SCHIMADZU gas chromatograph, equipped with a BPX70 capillary column (60 m x
0.25 mm × 0.25 μm) with helium as a carrier gas. The total content of fatty acids was
calculated as 90% of ether extract [Kratz 2003]. The intake of digestible FAs from a diet
was calculated regarding their intestinal digestibility [Jřrgensen et al. 1992, 1993]. The
protein, fat and fatty acids contents of the empty body weight (EBW) were calculated as
a sum of their content of soft tissues, non-edible parts and viscera with blood. Efficiency
of utilization of C18:2n-6 (LA) and C18:3n-3 (ALA) were calculated as: daily deposition
(g) of LA or ALA in the EBW/daily intake (g) of LA or ALA.
Fatty acids source of diets was used as the main factors in the variance analysis,
and the Tuckey-test was used to compare differences between means. All calculations
were performed using STATGAFICS Centurion Software version XV [2005].