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

Score Function for the Optimization of the Performance of Forward Fill/Flush Differential Flow Modulation for Comprehensive Two-Dimensional Gas Chromatography

Modulation is the key element of the comprehensive 2D gas chromatography separation. Forward fill/flush flow modulation is cost effective, robust and suitable for analysis of a wide range of samples. Even though this modulation system is well known, studies regarding its optimization are sparse. In this work, based on hundreds of experiments involving multiple column sets and modulation conditions, an approach was proposed that permits to facilitate the choice of the forward fill/flush flow modulation parameters. A score function was developed that allows to predict the forward fill/flush flow modulation process efficiency as judged by the modulated peak shape. The score function was based on the physical rules for optimized and quantitative forward fill/flush flow modulation proposed in our previous work, which state that the sum of the fill and flush modulation distances should be close to the modulation channel length and that the ratio of the flush and fill distances should be sufficiently high for efficient channel flushing. The score function was embedded in a freely available tool in the form of a forward fill/flush flow modulation calculator, which allows the user either to quickly check the relevancy of the modulation operating conditions or to obtain a suggestion for optimal modulation parameters.

Star-poly(ε-caprolactone) as the stationary phase for capillary gas chromatographic separation

This work presents the separation performance of star-poly(ε-caprolactone) (star-PCL) as the stationary phase for capillary gas chromatography (GC). The statically coated star-PCL column showed a column efficiency of 3345 plates per m and moderate polarity. Importantly, the star-PCL column exhibited high selectivity and resolving capability for more than a dozen mixtures covering a wide-ranging variety of analytes and isomers. Among them, the star-PCL column displayed advantageous resolving capability over the commercial DB-1701 column for aromatic amine isomers such as toluidine, chloroaniline and bromoaniline. Moreover, it was applied for the determination of isomer impurities in real samples, showing good potential in GC applications.

Fatty Acid Composition of Lamb Liver, Muscle, And Adipose Tissues in Response to Rumen-Protected Conjugated Linoleic Acid (CLA) Supplementation Is Tissue Dependent

The tissue-specific response to rumen-protected conjugated linoleic acid supply (rpCLA) of liver, two muscles, and three adipose tissues of heavy lambs was studied. Twenty-four lambs, 8 months old, divided into 4 groups of 6, were fed at libitum on a ration supplemented without or with a mixture of rpCLA. Silica and hydrogenated soybean oil was the rpCLA coating matrix. The lambs were slaughtered at 11 months of age. Tissues were collected and analyzed for their FA profiles. The dietary rpCLA supplement had no influence on carcass fatness nor on the fat content of the liver and tissues and had little influence on the FA profiles of these tissues. In the adipose tissues, rpCLA increased the proportions of saturated FAs, 18:0 and 18:2t10c12, and decreased the proportions of monounsaturated FAs in the adipose tissues. In muscles, the effects were the opposite. The results suggest that Δ9 desaturase activity is inhibited by the rpCLA mixture in adipose tissues to a greater extent than in the other tissues.

Transcriptomic Changes in Liver of Young Bulls Caused by Diets Low in Mineral and Protein Contents and Supplemented with n-3 Fatty Acids and Conjugated Linoleic Acid

The aim of the present study was to identify transcriptional modifications and regulatory networks accounting for physiological and metabolic responses to specific nutrients in the liver of young Belgian Blue × Holstein bulls using RNA-sequencing. A larger trial has been carried out in which animals were fed with different diets: 1] a conventional diet; 2] a low-protein/low-mineral diet (low-impact diet) and 3] a diet enriched in n-3 fatty acids (FAs), conjugated linoleic acid (CLA) and vitamin E (nutraceutical diet). The initial hypothesis was that the administration of low-impact and nutraceutical diets might influence the transcriptional profiles in bovine liver and the resultant nutrient fluxes, which are essential for optimal liver function and nutrient interconversion. Results showed that the nutraceutical diet significantly reduced subcutaneous fat covering in vivo and liver pH. Dietary treatments did not affect overall liver fat content, but significantly modified the liver profile of 33 FA traits (out of the total 89 identified by gas-chromatography). In bulls fed nutraceutical diet, the percentage of n-3 and CLA FAs increased around 2.5-fold compared with the other diets, whereas the ratio of n6/n3 decreased 2.5-fold. Liver transcriptomic analyses revealed a total of 198 differentially expressed genes (DEGs) when comparing low-impact, nutraceutical and conventional diets, with the nutraceutical diet showing the greatest effects on liver transcriptome. Functional analyses using ClueGo and Ingenuity Pathway Analysis evidenced that DEGs in bovine liver were variously involved in energy reserve metabolic process, glutathione metabolism, and carbohydrate and lipid metabolism. Modifications in feeding strategies affected key transcription factors regulating the expression of several genes involved in fatty acid metabolism, e.g. insulin-induced gene 1, insulin receptor substrate 2, and RAR-related orphan receptor C. This study provides noteworthy insights into the molecular changes occurring as a result of nutrient variation in diets (aimed at reducing the environmental impact and improving human health) and broadens our understanding of the relationship between nutrients variation and phenotypic effects.

The use of 2-dimensional gas chromatography to investigate the effect of rumen-protected conjugated linoleic acid, breed, and lactation stage on the fatty acid profile of sheep milk

In this study, 2-dimensional gas chromatography (GC × GC) was used to obtain a detailed fatty acid (FA) profile of sheep milk and to evaluate the effects of a rumen-protected conjugated linoleic acid (rpCLA) supply, breed, days in milk (DIM), sampling period, and number of lambs suckling on the FA profile. Twenty-four ewes, from 3 autochthonous breeds of the Veneto Alps (Brogna, Foza, and Lamon), were housed in 6 pens (2 pens/breed), according to DIM (38 ± 23 d) and body weight (61 ± 13 kg). The ewes and their offspring of 3 pens (1 pen/breed) were fed ad libitum a total mixed ration (control), and the other animals received the same diet supplemented with 12 g/d per ewe, plus 4 g/d for each lamb older than 30 d, of an rpCLA mixture. The study lasted 63 d. Two composite milk samples for each ewe were prepared during the first and second months of the trial. The pooled milk samples were analyzed in duplicate for FA profile by 2-dimensional gas chromatography, which allowed us to obtain a detailed FA profile of sheep milk, with 170 different FA detected, including many that were present in small concentrations. The milk relative proportions of individual FA, groups of FA, or FA indices were analyzed by PROC MIXED of SAS (SAS Institute Inc., Cary, NC), considering diet, breed, DIM, and sampling period as sources of variation. The random effect of animal was used to test diet, breed, and DIM, whereas the effects of period were tested on the residual. Breed had a small influence on milk FA profile, mainly on branched- and odd-chain FA. Within breed, animal repeatability for the relative proportions of milk FA was notable for almost all monounsaturated FA and for saturated FA with 14 to 19 carbon atoms, except C16:0, and less so for polyunsaturated FA. The inclusion of rpCLA (CLA cis-9,trans-11 and CLA trans-10,cis-12) increased the presence of the same CLA isomers in the milk as well as that of CLA trans-9,trans-11, and decreased the proportions of de novo-synthesized short-chain FA. From a cluster analysis based on the matrix of correlation coefficients among all FA relative proportions, 3 main FA groups were observed: the first included mainly odd- or branched-chain saturated FA, C18:0, C16:0 and CLA trans-10,cis-12; the second included monounsaturated FA or polyunsaturated FA with 16 to 20 carbons, CLA cis-9,trans-11, and CLA trans-9,trans-11; and the third included short- to medium-chain saturated FA, polyunsaturated FA with 2 to 5 double bonds, and 3 CLA isomers not affected by rpCLA addition (CLA trans-11,cis-13, CLA cis-9,cis-11, and CLA cis-10,cis-12).