This study investigated the effects of dietary linolenic acid (C18:3n-3) v. linoleic acid (C18:2n-6) on fatty acid composition and protein expression of key lipogenic enzymes, acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase (SCD) and delta 6 desaturase (Δ6d) in longissimus muscle and subcutaneous adipose tissue of bulls. Supplementation of the diet with C18:3n-3 was accompanied by an increased level of n-3 fatty acids in muscle which resulted in decrease of n-6/n-3 ratio. The diet enriched with n-3 polyunsaturated fatty acids (PUFAs) significantly inhibited SCD protein expression in muscle and subcutaneous adipose tissue, and reduced the Δ6d expression in muscle. There was no significant effect of the diet on ACC protein expression. Inhibition of the Δ6d expression was associated with a decrease in n-6 PUFA level in muscles, whereas repression of SCD protein was related to a lower oleic acid (C18:1 cis-9) content in the adipose tissue. Expression of ACC, SCD and Δ6d proteins was found to be relatively higher in subcutaneous adipose tissue when compared with longissimus muscle. It is suggested that dietary manipulation of fatty acid composition in ruminants is mediated, at least partially, through the regulation of lipogenic enzymes expression and that regulation of the bovine lipogenic enzymes expression is tissue specific.

Changes in fatty acid composition of longissimus muscle and subcutaneous adipose tissue of German Holstein bulls induced by a grass-silage/n-3 fatty acid based intervention diet versus a maize-silage/n-6 fatty acid based control diet were analyzed and related to shifts in lipogenic gene expression, protein expression, and enzyme activity patterns. Significantly higher amounts of n-3 fatty acids and by mean factors of 2.2-2.5 decreased n-6/n-3 fatty acid ratios in both tissues were obtained upon n-3 fatty acid intervention. In longissimus muscle, these changes of fatty acid profiles were associated with reduced SREBP1c (p = 0.02), ACC (p = 0.00), FAS (p = 0.10) and SCD (p = 0.03) gene expression, Δ6D (p = 0.03) and SCD (p = 0.03) protein expression as well as SCD enzyme activity (p = 0.03). In subcutaneous adipose tissue, significantly reduced ACC (p = 0.00) and FAS (p = 0.01) gene expression, SCD protein expression (p = 0.02) and SCD enzyme activity (p = 0.03) were detected upon n-3 fatty acid intervention, although lower degrees of correlation between gene and corresponding gene products were obtained in relation to longissimus muscle. The study elucidates tissue-specific functional genomic responses to dietary fatty acid manipulation in regard to fatty acid profile tailoring of animal tissues.

The present study investigated the effects of dietary linolenic acid (ALA) versus linoleic acid (LA) on meat quality, fatty acid composition, and stearoyl-CoA desaturase (SCD) activity in longissimus muscle (MLD) and subcutaneous adipose tissue (SAT) of German Holstein bulls and the transfer of beneficial n-3 fatty acids into German corned beef sausages (GCB). Feeding LA- and ALA-enriched diets increased essential fatty acids in MLD and SAT. The ALA-supplemented diet decreased significantly the SCD activity in MLD and SAT, resulting in a reduced relative concentration of oleic acid in muscle. The relative proportion of CLAcis-9,trans-11 analyzed by HPLC was not different between groups in either tissue. GCB were produced by using the lean meat of bulls. Beef products of bulls fed the ALA-supplemented diet were rich in ALA and n-3 LC PUFA. Most importantly, there was no loss of n-3 fatty acids during processing under production conditions. Conclusively, the n-6/n-3 fatty acid ratio was beneficially low.

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The study investigated the dietary impact of 18:3n-3 vs. 18:2n-6 on fatty acid- and micronutrient concentration of beef muscle and the extent of diet- and processing-induced changes of lipid- and micronutrient concentrations of beef products made thereof (German Corned beef (GCB), tea sausage spread (TSS), scalded sausage (SS)). Beef and beef products were obtained from German Holstein bulls which either received a control diet consisting of maize silage and concentrate with soybean meal (41%), or an experimental diet of grass silage and concentrate plus rapeseed cake (12%) and linseed oil (3%). The study revealed that upon an 18:3n-3 vs. 18:2n-6 intervention the amounts of 18:3n-3, EPA and Σn-3 LC-PUFA were significantly increased by 2.6, 2.3 and 1.7 fold, respectively. Experimental diet significantly increased β-carotene contents, and the γ-tocopherol contents were decreased. During beef processing, n-3 PUFA from beef were found to be product-specifically transferred into the corresponding beef products. 18:3n-3 and Σn-3 LC-PUFA contents were found to be 1.4 and 1.5 times higher in GCB from grass silage- than maize silage-fed bulls. The trace element contents in GCB (iron, copper, zinc, selenium) were not affected by the diet; however γ-tocopherol contents were decreased by experimental diet. In conclusion, dietary n-3 PUFA were completely transferred into beef products unaffected by beef processing conditions.