How do n-3 fatty acid (short-time restricted vs unrestricted) and n-6 fatty acid enriched diets affect the fatty acid profile in different tissues of German Simmental bulls?

Recent advances in rapid and nondestructive determination of fat content and fatty acids composition of muscle foods

Conventional methods for determining fat content and fatty acids (FAs) composition are generally based on the solvent extraction and gas chromatography techniques, respectively, which are time consuming, laborious, destructive to samples and require use of hazard solvents. These disadvantages make them impossible for large-scale detection or being applied to the production line of meat factories. In this context, the great necessity of developing rapid and nondestructive techniques for fat and FAs analyses has been highlighted. Measurement techniques based on near-infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance and hyperspectral imaging have provided interesting and promising results for fat and FAs prediction in varieties of foods. Thus, the goal of this article is to give an overview of the current research progress in application of the four important techniques for fat and FAs analyses of muscle foods, which consist of pork, beef, lamb, chicken meat, fish and fish oil. The measurement techniques are described in terms of their working principles, features, and application advantages. Research advances for these techniques for specific food are summarized in detail and the factors influencing their modeling results are discussed. Perspectives on the current situation, future trends and challenges associated with the measurement techniques are also discussed.

Impacts of fat from ruminants' meat on cardiovascular health and possible strategies to alter its lipid composition

In the last few decades there has been increased consumer interest in the fatty acid (FA) composition of ruminant meat due to its content of saturated FAs, which have been implicated in diseases associated with modern life. However, recent studies have questioned the recommendations to reduce intake of fat, saturated FAs and cholesterol as a means of reducing the risk of cardiovascular disease. Interestingly, ruminant meat has some bioactive lipids such as C18:1t11 and C18:2 c9, t11 which have been reported to have positive effects on human health. In order to improve muscle fat composition from a human health standpoint, oilseeds, plant oils and marine oils can be used in ruminant diets. On the other hand, molecular mechanisms play an important role in the alteration of the FA composition of muscle fat. Genetics offer a wide range of possibilities for improvement of muscle fat composition by identifying different loci underlying the expression of quantitative traits. While significant progress has been made in characterizing the influence of diet on the FA composition of ruminant meat, the use of genetic tools can favor genotypes that could maximize their genetic potential through the diet. © 2016 Society of Chemical Industry.

Determination by GC×GC of fatty acid and conjugated linoleic acid (CLA) isomer profiles in six selected tissues of lambs fed on pasture or on indoor diets with and without rumen-protected CLA

In this study GC×GC was used to study the effects of pasture, hay, concentrate (indoor), and indoor plus 8 g/day of a rumen-protected conjugated linoleic acid (indoor-CLA) diets on the detailed fatty acid (FA) profiles of six tissues (muscles, fatty tissues, and liver) collected from 36 lambs. This powerful technique allowed the quantification of 128 FAs, of which 21 SFAs, 16 MUFAs, 19 PUFAs were identified by reference standards. The diets had similar, but not identical, effects on FA profiles (g/100 g FA) in the various tissues, as both indoor diets reduced total PUFAs (from 8.91 ± 6.27 to 8.06 ± 5.97; p < 0.05) and n-3 PUFAs (from 2.70 ± 2.37 to 1.50 ± 1.69; p < 0.01) and increased n-6 PUFA (from 3.76 ± 2.46 to 4.58 ± 3.42; p < 0.01), branched (from 2.37 ± 2.05 to 3.23 ± 0.54; p < 0.01), odd-chain FAs (from 5.88 ± 5.33 to 7.07 ± 1.51; p < 0.01) compared to pasture. Indoor-CLA increased CLAc9,t11 (from 0.42 ± 0.13 to 0.53 ± 0.19; p < 0.01), CLAt10,c12 (from 0.07 ± 0.06 to 0.12 ± 0.22; p < 0.05), and CLAc11,t13 (from 0.02 ± 0.04 to 0.05 ± 0.04; p < 0.05) compared to indoor.

Effects of pasture versus confinement and marine oil supplementation on the expression of genes involved in lipid metabolism in mammary, liver, and adipose tissues of lactating dairy cows

Research was conducted to evaluate the effects of management system (MS), marine lipid supplementation (LS), and their interaction on the relative mRNA abundance of 11 genes involved in lipid synthesis in mammary, liver, and subcutaneous adipose tissues in lactating dairy cows. These genes included those involved in FA uptake (LPL), de novo FA synthesis (ACACA, FASN), FA desaturation (SCD1, FADS1, FADS2), and transcriptional regulation of lipogenesis (SREBF1, SCAP, INSIG1, THRSP, and PPARG). Forty-eight peripartal Holstein cows were blocked by parity and predicted calving date and assigned to either a pasture (n=23) or confinement (n=25) system. Within each system, cows were allocated randomly (7-9 cows per treatment) to a control (no oil supplement) or 1 of 2 isolipidic (200 g/d) supplements, fish oil (FO) or microalgae (MA), for 125 ± 5 d starting 30 d precalving. The experiment was conducted as a split-plot design, with MS being the whole plot treatment and LS as the subplot treatment. At 100 ± 2 DIM, 4 cows from each treatment combination (24 cows in total) were euthanized and tissue samples were collected for gene expression analysis. No interactions between MS and LS were observed regarding any of the variables measured in this study. Milk production (34.0 vs. 40.1 kg/d), milk fat (1.10 vs. 1.41 kg/d), protein (0.95 vs. 1.22 kg/d), and lactose (1.56 vs. 1.86 kg/d) were lower for pasture compared with confinement. The effect of LS on milk production and milk composition (yields and contents) was significant only for milk fat content that was reduced with MA compared with FO (3.00 vs. 3.40%) and the control (3.56%). The mammary mRNA abundance of PPARG (-32%) and FASN (-29%) was lower in grazing compared with confined cows, which was accompanied by reduced (-43%) secretion of de novo synthesized fatty acids in milk. Grazing was associated with reduced expression of ACACA (-48%), FASN (-48%), and THRSP (-53%) in subcutaneous adipose tissues, which was consistent with the lower body condition score (i.e., lower net adipose tissue deposition) in grazing compared with confined cows. Feeding either FO or MA downregulated hepatic expression of FASN, SCD1, FADS2, and THRSP. The reduced secretion of de novo synthesized fatty acids in milk of grazing cows compared with confined cows might be related in part to the downregulation of genes involved in lipid synthesis, and that LS have tissue-specific effects on expression of genes involved in lipid metabolism, with liver being the most responsive tissue.

A grass-based diet favours muscle n-3 long-chain PUFA deposition without modifying gene expression of proteins involved in their synthesis or uptake in Charolais steers

N-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) are subject of growing interest as they are of particular relevance for meat quality and human health. However, their content in the muscles of cattle is generally low probably as the complex result of their biosynthesis from dietary n-3 PUFA in the muscle and/or in other tissues/organs and of their subsequent uptake by the muscle. In view of this, this study aimed at understanding whether the changes in the muscle n-3 LCPUFA content, depending on the diet (maize silage v. grass) or the muscle type (Rectus abdominis, RA v. Semitendinosus, ST) in 12 Charolais steers, were related to variations in the gene expression of proteins involved in n-3 LCPUFA biosynthesis or cellular uptake. Tissue fatty acid composition was analysed by gas-liquid chromatography and mRNA abundance of proteins by quantitative real-time PCR. The grass-based diet resulted in a 2.3-fold (P < 0.0002) increase in both RA and ST n-3 LCPUFA content compared with the maize silage-based diet, whereas no difference in the expression of genes involved in n-3 LCPUFA biosynthesis and uptake was observed between diets. ST exhibited a 1.5-fold higher n-3 LCPUFA content than RA (P < 0.003), whereas the gene expression of proteins involved in n-3 LCPUFA biosynthesis and uptake was 1.3- to 18-fold higher in RA than in ST (P < 0.05). In conclusion, diet- or muscle type-dependent changes in the muscle n-3 LCPUFA content of Charolais steers did not seem to be mediated by the gene expression regulation of proteins involved in the biosynthesis or uptake of these fatty acids.