Arachidonic acid (AA) content, long-chain n-3 polyunsaturated fatty acid (PUFA) equivalent [LCE; calculated as 0.15 x linolenic acid (LA) + eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)], and PUFA n-6/PUFA n-3 ratio were determined in meat [breast meat (BM), thigh meat (TM), and fillets (F), respectively] within four sets of chickens, five sets of turkeys, one set of common carp, and four sets of rainbow trout, fed either commercial diet or diets with manipulated PUFA n-3 and PUFA n-6 contents. AA content was within the range of 20 mg/100 g (F of rainbow trout fed the diet with linseed oil, LO) to 138 mg/100 g (TM of chickens fed restrictively the diet based on maize to the age of 90 days). AA content in BM of turkeys fed the diet with LO or fish oil (FO) did not differ (P > 0.05) from that of rainbow trout F. LCE was in the range of 16 mg/100 g (BM of turkeys fed a commercial feed mixture) to 681 mg/100 g (F of rainbow trout fed a commercial feed mixture). With regard to BM, only turkeys fed the diet with LO deposited more (P < 0.01) LCE (71 mg/100 g) as compared to all other poultry sets except turkeys fed the diet with FO (123 mg/100 g). Apart from all fish samples, also both BM and TM of turkeys fed the diet with either LO or FO met the recommended value of the PUFA n-6/PUFA n-3 ratio (<4). AA content in the tissue increased significantly (P < 0.001) with increasing dietary LA in both all chicken tissues and all turkey tissues, which is contrary to the suggested strong metabolic regulation of the AA formation. When all tissues within all animal species were taken as a one set, both AA percentage and EPA + DHA percentage in the tissue (Y, %) decreased (P < 0.001) with increasing fat content in the tissue (X, %), according to the equation Y = 4.7 - 0.54X (R (2) = 0.41) and Y = 6.0 - 0.33X (R (2) = 0.35), respectively. AA content in chicken BM, chicken TM, and turkey BM, respectively, decreased linearly (P < 0.01) with increasing live weight reached at the slaughter age.

Two groups of dairy cows, Czech Red-pied × Ayrshire × Red Holstein crossbreds, received a diet with either production mixture with rapeseed, rapeseed cakes and rapeseed oil (Energol; E-group; final feed mixture with 62 g of crude fat per kg of dry matter, DM) or control production mixture (C-group; crude fat content in total feed mixture 37 g/kg DM). Milk samples were taken on the 14 th , 30 th , 60 th and 90 th day of lactation, and basic milk constituents and fatty acid content in milk fat were determined. E-and C-groups did not differ in either milk yield or yield of milk fat, milk protein and lactose (P > 0.05). Lactose, calcium, milk protein and casein content increased linearly (P < 0.05) with the increasing day of lactation both in E-milk and in C-milk. Casein content in E-milk was lower (P < 0.05) than in C-milk but total lipid content did not differ (P > 0.05) from that in C-milk. Dietary rapeseed decreased (P < 0.05) palmitic acid content in milk by 20 percentage units and at the same time increased (P < 0.05) oleic acid content by 10 percentage units in comparison with control milk; the ratio of total C16/total C18 fatty acids was consequently twice lower (P < 0.01) in E-milk. As far as polyunsaturated fatty acids (PUFA) are concerned, the contents of linoleic acid (LA), α-linolenic acid (LNA) and eicosapentaenoic + docosahexaenoic acid were higher (P < 0.05) in E-milk; however, the PUFAn-6/PUFAn-3 ratio was not different between E-and C-milk. It was concluded that 1 litre of E-milk could provide 20% of both LA and LNA daily requirement.

Abstract. The effect of crossbreeding on the content of polyunsaturated fatty acids (PUFA) in intramuscular adipose tissue of the Musculus longissimus pars thoracis of slaughter bulls was studied. The differences among 8 genotypes of bulls was most significant (p<0.01) in C18:3, C20:4, C22:4, C22:5 and C22:6. The content of linolenic acid (C18:3) in the Czech Spotted Cattle (control group) was 0.526%, the highest in the Czech Spotted x Piedmont cattle crosses (0.659 %), and the lowest in crosses with the Belgian breed (0.186 %). We evaluated the content of C18:3 (n-6 and n-3) and among the genotypes the differences in the content were insignificant. Compared with the control group all the evaluated genotypes showed a higher representation of C18 n-3, which does not apply to the isomer C18 n-6. At low percent values we detected insignificant differences in changes in content of isomers C22:5. Factors such as the age of the animals and the carcass weight had no effect on the structure of fatty acids. More important was the content of the intramuscularly adipose tissues. With increasing content of intramuscularly adipose tissue the values of C18:3 (n-3 and n-6) and C22:5 (n-3 and n-6) decreased as did the content of other acids belonging to PUFA (p<0.01).

Effect of addition 6% of linseed oil (designated L06), 6% and 10% of fish oil (R06 and R10) to feed on the fatty acid spectrum of common carp (Cyprinus carpio L.) was investigated. The basic feedmixture which was used as a control variant (K – 34% protein; 9% fat) and the three with oil addition (L06, R06 and R10) were fed to carp fingerling (43.25 g average weight) for 60 days – from 23rd April to 20th June. Before that the fish were fed for 2 month by whey grain and commercial feed for carp fingerling in pond fish-culture (KP feed mixture – 33% protein; 5% fat) at daily feeding rate 1.5% of actually fish mass. This procedure was intended to create feeding conditions closest to those witnessed in market fish farmed in ponds during the vegetation season nevertheless the spectrum of fatty acids present in the fish muscle at the experiment’s beginning did not fully correspond to what was observed in carps living in ponds and fed by cereals.An addition of 6% of linseed oil to the feed lowers the content of the oleic acid and MUFA and, at the same time, it boosts the contents of the α-linoleic acid, n-3 PUFA and the general PUFA in the meat of carp fed on mixtures thus enriched. Additions of 6% and 10% of fish oil to the feed for common carp increases the content of the eicosapentaenoic acid. The 10% addition proved beneficial for also the ratio of n-3/n-6 PUFA. The high content of the docosapentaenoic acid and the general PUFA in the meat of fish as early as the beginning of the experiment resulted in a smaller number of significant changes in the spectrum of fatty acids (particularly the docosahexaenoic acid, PUFA and n-3/n-6 PUFA) found in the fish meat of the L06, R06 and R10 experimental variants.

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