Overview of conjugated linoleic acid formation and accumulation in animal products

Multiple biological activities and biosynthesis mechanisms of specific conjugated linoleic acid isomers and analytical methods for prospective application

Conjugated linoleic acid (CLA) is a collective term for the octadecadienoic acid isomers containing conjugated double bonds. This article reviewed CLA isomers from biological activities, biosynthesis mechanisms and analytical methods. The biological activities of CLA isomers in anti-obesity, cardiovascular protection, diabetes management and anti-cancer in vitro and in vivo were mainly reviewed. More attention has been paid to the production of the specific CLA isomer due to its biological activity. The biosynthesis methods of CLA isomers, such as dietary modification in ruminants and fermentation by microorganisms & enzymes, were systematically introduced. A rapid, accurate and economic analysis method will promote the research in both biological activities and biosynthesis mechanisms of CLA isomers. The merits of UV spectrometry, GC, HPLC, MS and CE used in the analysis of CLA isomers were also compared in detail. This paper aims to put into perspective the current status and future trends on CLA isomers.

A Short-Term Supplementation with a Polyphenol-Rich Extract from Radiata Pine Bark Improves Fatty Acid Profiles in Finishing Lambs

The aim of this study was to evaluate the effects of a short-term supplementation with a polyphenol-rich extract from radiata pine bark (PBE) on animal performance, blood parameters, and fatty acid (FA) profiles in finishing lambs. Twenty-seven Suffolk lambs (4 months old) fed a finishing diet were randomly assigned to one of the following treatments: diet without PBE or diet supplemented with PBE on a 1 or 2% dry matter (DM) basis, for 35 d (14 d adaptation and 21 d of experimental period). Data were compared using Tukey's test and orthogonal and polynomial contrasts. The results indicated that the supplementation with PBE increased (p = 0.008) relative growth rate (RGR) and improved (p = 0.003) protein conversion (CPC), whereas weight gain, carcass characteristic, and blood parameters were unaffected (p ≥ 0.106). Total mono- and polyunsaturated FAs, conjugated linoleic acid (CLA), and vaccenic and oleic acids were linearly increased (p ≤ 0.016) by PBE supplementation. In contrast, total saturated FAs (ΣSFA), Σn-6/Σn-3 ratio, atherogenicity index (AI), thrombogenic index (TI), and the proportion of elaidic acid were linearly decreased (p ≤ 0.018). In conclusion, the supplementation with 1 or 2% DM of PBE improves subcutaneous FA profiles by increasing CLA and reducing ΣSFA, Σn-6/Σn-3 ratio, AI, and TI. Additionally, PBE supplementation has the potential to improve RGR and CPC, with unaffected intake, growth performance, blood parameters, or carcass characteristics.

Supplementation with Sunflower/Fish Oil-Containing Concentrates in a Grass-Based Beef Production System: Influence on Fatty Acid Composition, Gene Expression, Lipid and Colour Stability and Sensory Characteristics of Longissimus Muscle

Beef contains an array of conjugated linoleic acid (CLA) isomers for which positive effects have been reported in animal models of human disease. The objectives were to develop a CLA-enriched beef production system and to assess its quality. Sixty Spring-born heifers were housed in Autumn and offered unwilted grass silage and a barley/soyabean concentrate or wilted grass silage and a concentrate containing sunflower oil and fish oil. In May, both groups were offered either pasture for 22 weeks, restricted pasture and sunflower oil and fish oil for 22 weeks, or pasture for 11 weeks and restricted pasture and sunflower oil and fish oil for the final 11 weeks. The predominant CLA isomer in beef was cis9, trans11 representing on average, 80% total CLA. The modified winter diet followed by supplementation for 22 weeks resulted in beef that had a CLA concentration that was higher, at a comparable intramuscular fatty acid concentration, than previously reported. The lipid and colour stability (over 10 days in modified atmosphere packaging) and sensory characteristics were generally not negatively affected. There were minor effects on the expression of candidate genes involved in lipid metabolism. Consumption of this beef would make a substantial contribution to the quantity of CLA suggested to have a positive effect on consumer health.

Feeding Dairy Ewes with Fresh or Dehydrated Sulla (Sulla coronarium L.) Forage. 2. Effects on Cheese Enrichment in Bioactive Molecules

Sulla is a tanniferous legume species largely used as fresh or preserved forage in the ruminants' diets. Due to its content in polyphenols with antioxidant activity, especially condensed tannins (CT), fresh sulla forage (FSF), when eaten by ruminants, is able to enrich animal products with antioxidant molecules and polyunsaturated fatty acids (PUFA) that are beneficial for consumers' health. Dehydration represents a valid alternative to haymaking to preserve these properties also in periods when FSF is unavailable. In this research, the effects of ewes' diets based on sulla hay (SH), pelleted dehydrated sulla forage (DSF) or FSF were evaluated on cheese physico-chemical traits, including fatty acid (FA) profile, vitamins A and E, polyphenols, antioxidant capacity and oxidative stability. The individual daily milk from 10 first lambing (FL) and 10 third lambing (TL) Valle del Belìce ewes at about 60 days in milk, divided homogeneously into 5 groups fed different diets in a partial 5 × 2 Latin square design with 2 phases, and the bulk milk of farming ewes fed only on natural pasture, were used in 2 sessions of micro cheese-making to manufacture cheeses, sampled at 48 h of ripening. The experimental diets were: SHL = SH ad libitum; DSF2 = 2 kg/day DSF per head plus SH ad libitum; FSF2 = 2 kg/day FSF per head plus SH ad libitum; FSF4 = 4 kg/day FSF per head plus SH ad libitum; FSFL = FSF ad libitum. Concentrate was supplied at the amount of 0.8 or 1.2 kg/day per head for FL and TL, respectively. Cheese health properties greatly improved with FSFL diet, based on the exclusive use of fresh forage, that induced the increase in the content of molecules with antioxidant activity, as vitamin A, vitamin E and polyphenols, enhancing the oxidative stability, and the level of PUFA as rumenic acid (C18:2 c9t11) and α-linolenic acid (ALA, C18:3n-3). Cheeses from the DSF2 group showed levels of vitamin A, vitamin E and PUFA higher than SHL cheeses and comparable to those of FSF4 cheeses, whereas their ALA content was not different from that of FSFL cheeses. Evaluating those molecules affected by the level of fresh forage in the diet for their ability to trace the animals' feeding regime, ALA and its ratio with linoleic acid (LA, C18:2n-6) (LA/ALA) exhibited an effective role as biomarker in discriminating cheese from animals fed fresh forage-based diets. The results showed how dehydrated sulla pellets, as an alternative to hay in periods of limited availability of fresh forage, can preserve the nutritional and health properties of dairy products with regards to their antioxidant capacity and FA profile.

Proteomics Insights into the Gene Network of cis9, trans11-Conjugated Linoleic Acid Biosynthesis in Bovine Mammary Gland Epithelial Cells

The objective of the study was to elucidate the stearoyl-coenzyme A desaturase (SCD1)-dependent gene network of c9, t11-CLA biosynthesis in MAC-T cells from an energy metabolism perspective. The cells were divided into the CAY group (firstly incubated with CAY10566, a chemical inhibitor of SCD1, then incubated with trans-11-octadecenoic acid, (TVA)), the TVA group (only TVA), and the control group (without CAY, TVA). The c9, t11-CLA, and TVA contents were determined by gas chromatography. The mRNA levels of SCD1 and candidate genes were analyzed via real-time PCR. Tandem mass tag (TMT)-based quantitative proteomics, bioinformatic analysis, parallel reaction monitoring (PRM), and small RNA interference were used to explore genes involved in the SCD1-dependent c9, t11-CLA biosynthesis. The results showed that the SCD1 deficiency led by CAY10566 blocked the biosynthesis of c9, t11-CLA. In total, 60 SCD1-related proteins mainly involved in energy metabolism pathways were primarily screened by TMT-based quantitative proteomics analysis. Moreover, 17 proteins were validated using PRM analysis. Then, 11 genes were verified to have negative relationships with SCD1 after the small RNA interference analysis. Based on the above results, we concluded that genes involved in energy metabolism pathways have an impact on the SCD1-dependent molecular mechanism of c9, t11-CLA biosynthesis.

Relationships between intramuscular fat percentage and fatty acid composition in M. longissimus lumborum of pasture-finished lambs in New Zealand

This paper reports relationships between fatty acids (FAs) and intramuscular fat (IMF)% in M. longissimus lumborum samples from 108 pasture-fed ewe lambs. Samples ranged in IMF from 1 to 6%. Relationships between %FA with total IMF% were mainly linear with percentages of saturated and monounsaturated FAs (MUFA), including trans-FAs, increasing and polyunsaturated FAs decreasing as IMF% increased. Normalized FA content data at 5.5% relative to 1.5% IMF, showed the highest relative increase for C14:0 as rates of endogenous synthesis increase with higher IMF deposition. This can be related to enhanced C12:0 elongation and lower rates of C14:0 desaturation, supported by a preferential desaturation of C18:1 trans-11 and C18:0 compared with C14:0 and C16:0 as IMF increased. The greatest normalized increase after C14:0 was anteisoC17:0 followed by other branched chain FAs and then trans-MUFA and C18:2 cis-9,trans-11. Finally, C22:6 and C22:5 showed higher relative increase than C20:5 indicating greater rates of elongation and desaturation past C20:5 at higher levels of fatness.

Crude glycerin in the supplementation of crossbred heifers in tropical pastures

Crude glycerin (CG) is a biodiesel byproduct that has been tested as an alternative feed additive for use in beef production. After being absorbed, it is used in the liver to produce glucose, an important precursor of intramuscular fat in ruminants. This study aimed to evaluate the effect of CG (439 g/kg glycerol) on the performance and meat quality of crossbred heifers finished in Urochloa brizantha cv. Marandu. Thirty-six heifers with an initial BW of 301.5 ± 23.02 kg were used. They were supplemented for 154 days with the following levels of CG: mineral mixture (without CG), 33.3, 66.6 and 99.9 g/kg CG in the DM of the supplement. Supplement or pasture DM intakes, slaughter BW and carcass traits were not influenced (P > 0.05) by increasing levels of CG. The total fat content of the meat, the vaccenic (18:1 n-7t) and conjugated linoleic acid (18:2 c9-t11) increased with the addition of CG in the diet (P < 0.05). Crude glycerin can be included up to 99.9 g/kg of the total diet without changing the performance of crossbred heifers finished in the tropical pasture.

Effects of the Inclusion of Different Levels of Dietary Sunflower Hulls on the Colostrum Compositions of Ewes

Simple Summary

Increasing the cost of roughages, as a result of high demand by livestock producers, leads to a search for alternative sources. Plant by-products such as sunflower hulls can be used as an alternative source of fiber. This manuscript is a part of ongoing research to identify the best levels to be used without negative effects on ruminant animals’ performances.

Abstract

This study investigated the effects of supplementing different levels of sunflower hulls (SFH) to the complete feed of late-gestation pregnant ewes on the nutritive and fatty acids profile of colostrum at three and 48 h postpartum. In this study, 24 primiparous lactating Naemi ewes were randomly selected at parturition from four dietary groups as follows: (1) C (control), total mixed ration (TMR; 0% SFH), (2) S12, TMR1 with 12% SFH (level 1), (3) S20, TMR2 with 20% SFH (level 2), and (4) S28, TMR3 with 28% SFH (level 3). The body condition scores were estimated 30 days prepartum. Colostrum samples were collected at three and 48 h postpartum to measure the nutritive values and fatty acids profiles. Data were analyzed as a complete randomized design with repeated measures and via Pearson’s correlation and regression analyses. The results indicated a numerical correlation (R² = 0.42; p < 0.09) between the body condition score and both colostrum fat and total solids. SFH increased the colostrum fat % (p < 0.05), especially for S12 and S20, following a cubic trend. Additionally, the colostrum from S12 and S20 ewes had a higher proportion of unsaturated fatty acids (USFAs), omega3 and lower levels of saturated fatty acids (SFAs), other than margaric acid (C17) and stearic acid (C18), SFA/USFA, and omega 6/omega 3. Furthermore, the regression analysis of the fatty acid classes and indices indicated a quadratic relationship between the parameters and SFH levels. The results confirm that the inclusion of SFH at levels greater than 20% may have a negative effect on some fatty acid parameters as a result of the high lignin intake. In conclusion, up to 20% SFH can be used in a complete feed for pregnant ewes without negative effects on the colostrum fat content and fatty acids profiles.

cis 9, trans 11, but not trans 10, cis 12 CLA isomer, impairs intestinal epithelial barrier function in IPEC-J2 cells and mice through activation of GPR120-[Ca2+]i and the MLCK signaling pathway

This study aimed to investigate the effects of conjugated linoleic acid (CLA) on intestinal epithelial barrier function and explore the underlying mechanisms. IPEC-J2 cells and mice were treated with different CLA isomers. The intestinal epithelial barrier function determined by transepithelial electrical resistance (TEER), the expression of tight junction proteins, and the involvement of G-protein coupled receptor 120 (GPR120), intracellular calcium ([Ca2+]i) and myosin light chain kinase (MLCK) were assessed. In vitro, c9, t11-CLA, but not t10, c12-CLA isomer, impaired epithelial barrier function in IPEC-J2 by downregulating the expression of tight junction proteins. Meanwhile, c9, t11-CLA isomer enhanced GPR120 expression, while knockdown of GPR120 eliminated the impaired epithelial barrier function induced by c9, t11-CLA isomer. In addition, c9, t11-CLA isomer increased [Ca2+]i and activated the MLCK signaling pathway in a GPR120-dependent manner. However, chelation of [Ca2+]i reversed c9, t11-CLA isomer-induced MLCK activation and the epithelial barrier function impairment of IPEC-J2. Furthermore, inhibition of MLCK totally abolished the impairment of epithelial barrier function induced by c9, t11-CLA. In vivo, dietary supplementation of c9, t11-CLA rather than t10, c12-CLA isomer decreased the expression of intestinal tight junction proteins and GPR120, increased intestinal permeability, and activated the MLCK signaling pathway in mice. Taken together, our findings showed that c9, t11-CLA, but not t10, c12-CLA isomer, impaired intestinal epithelial barrier function in IPEC-J2 cells and mice through activation of GPR120-[Ca2+]i and the MLCK signaling pathway. These data provided new insight into the regulation of the intestinal epithelial barrier by different CLA isomers and more references for CLA application in humans and animals.

Dietary Omega-3 Source Effect on the Fatty Acid Profile of Intramuscular and Perimuscular Fat-Preliminary Study on a Rat Model

Fatty acids from the omega-3 family are an important element of both human and animal diets. Their activity involves a range of functions for the functioning of a whole organism, and their presence in animal diets can be considered as a means for animal origin product enrichment for human benefit or as compounds profitable for an animal's health status. The aim of this preliminary study was to compare the effect of supplements rich in omega-3 fatty acids (linseed oil, linseed oil ethyl esters, and fish oil) in rat feed on the fatty acid profile of their intramuscular and perimuscular fat. The results demonstrated beneficial changes in fatty acid profiles (a decrease in saturated acids, an increase in unsaturated ones, i.e., omega-3 acids share) of examined tissues in the case of all supplements however, particular attention should be paid to linseed oil ethyl esters, which significantly increased the content of all omega-3 acids. Supplementation of animal diet with linseed oil ethyl esters may be beneficial for both animals, as omega-3 fatty acids exhibit profitable properties related to an animal's health status and productivity, and humans who consume such enriched products.

Total conjugated linoleic acid content of ruminant milk: The world status insights

Conjugated linoleic acid (CLA) content of ruminant milk reported in published research papers (n = 65) from January 1995 to March 2020 around the world were analyzed to estimate the overall mean CLA value. The CLA content of ruminant milk samples was grouped according to geographical regions (Europe, South America, North America, Oceania, Asia, and Africa). The total CLA content of milk samples from cows, sheep, goats, yaks, and llama retrieved from the collected data ranged between 0.06 and 2.96% of total fatty acids. There is a wide variation of pooled estimated mean content of CLA in milk among the study regions and were highest in Oceania with 1.33% (95% confidence interval (CI): 1.16 - 1.49%) of total fatty acids. Though several factors have been reported to influence the CLA content of milk, the effect of the "geographical origin" was only considered in the present manuscript as one of the main factors in this respect.

Effect of Molecular Form of Conjugated Linoleic Acid on Oxidative Stability : Comparison of Triacylglycerol and Phosphatidylcholine Form

The health benefits of conjugated linoleic acid (CLA), a functional lipid with anti-cancer, anti-obesity, and hypotensive activity, have garnered increasing attention. The current study was conducted to determine the oxidative stability of CLA in the form of triacylglycerol (CLA-TAG) and phosphatidylcholine (CLA-PC) at the sn-2 position. Oxidation was performed at 30°C or 40°C in the dark. Hydroperoxides, as the primary oxidation products, were analyzed using diphenyl-1-pyrenylphosphine. Thiobarbituric acid reactive substances (TBARS) and volatile compounds were monitored as secondary oxidation products. The results suggest that CLA-PC was more stable against oxidation than CLA-TAG from the perspective of suppression of the generation of hydroperoxides and TBARS. However, CLA-PC produced more volatile compounds than CLA-TAG. We suggest that choline was released during the oxidation of CLA-PC, and acted as an antioxidant. The ensuing reaction between choline and hydroperoxide induced the generation of volatile compounds such as pentanal, hexanal, and heptanal.

Effect of Soy Lecithin Supplementation in Beef Cows before Calving on Colostrum Composition and Serum Total Protein and Immunoglobulin G Concentrations in Calves

Simple Summary

Until recently, fat supplements were considered merely as a source of energy for cows during transition. However, individual fatty acids included in fat supplements may clearly induce different production and metabolic responses, which in consequence change the nutritional value of bovine colostrum. Therefore, it is necessary to consider the type of fat additive to use in feed ration. This study aimed to determine an effect of soy lecithin supplementation on beef cow’s colostrum composition and selected blood parameters in their calves. Obtained results suggest that soy lecithin addition in cows before calving has a beneficial impact on colostrum composition. This concerns mainly an increase of linoleic acid in colostrum, which may influence IgG activity in calf serum. In turn, higher content of these components in colostrum may contribute to improve calves’ survival rate during the first weeks of their life.

Abstract

The aim of this study was to investigate the impact of soy lecithin supplementation in beef cow’s nutrition on colostrum composition and serum concentrations of immunoglobulin G (IgG) and serum total protein (STP) in calves. Twenty pregnant Charolaise cows were assigned to two groups. In the supplementation group (n = 10) during the last four weeks of pregnancy, soy lecithin was administrated in an amount of 20 g/cow/day. In both groups, basic composition (protein, fat, lactose, dry matter), somatic cell count (SCC), total bacteria count (TBC), IgG concentration, and fatty acids profile were determined in colostrum samples. Moreover, STP and IgG concentration were measured in calves’ blood samples on the 3rd, 7th, 14th, and 21st days of life, mothered by supplementation and control cows. Animals fed with soy lecithin before calving produced colostrum with a higher (p = 0.049) level of linoleic acid (C18:2 n-6). In addition, these results showed that soy lecithin supplementation has contributed to an increase (p = 0.029) of serum IgG in calves on the 14th day of life. The impact of such change in colostrum on IgG levels on calves serum and their half-life need further analysis.

The dietary c9,t11-conjugated linoleic acid enriched from butter reduces breast cancer progression in vivo

The c9,t11-conjugated linoleic acid (CLA), which is the minor polyunsaturated fatty acid (PUFA) naturally present in butter, has gained attention due to its important preventive effect against breast cancer in vitro. In this paper, the enrichment of c9,t11-CLA from butter was optimized and the preventive effect of dietary c9,t11-CLA against breast cancer in vivo was investigated. Results showed that the concentration of c9,t11-CLA increased more than 10 times via a one-step urea complexation. Furthermore, the dietary c9,t11-CLA showed obvious preventive effect against breast cancer in decreasing the tumor weight and volume, and reducing the tumor incidence up to 50%. In addition, the expression of progesterone receptor and Ki-67 decreased significantly with the treatment of c9,t11-CLA. In conclusion, the dietary c9,t11-CLA enriched from butter showed a preventive effect against breast cancer in vivo via the inhibition of the hormonal receptor and cell proliferation. PRACTICAL APPLICATIONS: This paper provided new insight into the preparation of specific c9,t11-CLA isomer. It can be enriched from butter in large-scale with low-cost by urea complexation. Meanwhile, the enriched dietary c9,t11-CLA can be further processed into cancer prevention functional foods.

Factors affecting levels of volatile 4-alkyl branched-chain fatty acids in sheep milk from 2 contrasting farming systems in New Zealand

Knowledge of factors influencing the levels of 4-alkyl branched-chain fatty acid (vBCFA), and consequently the "sheepy flavor" intensity of New Zealand sheep milk, is currently limited. In this study, we investigated the effects of 2 contrasting farming systems (fully housed/mid-lactation or pasture-grazed/late lactation) on the levels of vBCFA in sheep milk on a commercial farm in the North Island of New Zealand. Fully housed/mid-lactation ewes were housed 24 h/d and fed a total mixed ration. Pasture-grazed/late-lactation ewes were grazed 24 h/d and offered approximately 40% supplements because of poor pasture growth resulting from dry and hot climatic conditions. Any effects of genetics, age, lactation stage, feed composition, lambing date, or the environment in the housing barn or outdoors were confounded. The results obtained in this study were descriptive rather than definitive, because of the limitations of the experimental design. Levels of 4-methyloctanoic acid and 4-methylnonanoic acid in milk from fully housed/mid-lactation ewes increased during the trial period, but remained low in milk from pasture-grazed/late-lactation ewes. Levels of 4-ethyloctanoic acid in milk from the 2 groups of ewes were comparable throughout the trial. Increases in levels of 4-methyloctanoic acid and 4-methylnonanoic acid in sheep milk were associated with lactation stage and the proportion of lucerne silage fed to ewes. The level of free-form 4-ethyloctanoic acid was positively correlated with the proportion of soy meal in the diet and negatively correlated with the proportion of barley. Milk from fully housed/mid-lactation ewes had a higher flavor values than milk from pasture-grazed/late-lactation ewes because of its higher total amounts of vBCFA.

Effects of supplemental plant oils on rumen bacterial community profile and digesta fatty acid composition in a continuous culture system (RUSITEC)

Lipid supplementation of ruminant diets may trigger changes in the ruminal microbiota and in anaerobic digestion. Changes in the bacterial community composition and in the fatty acid hydrogenation caused by the addition of different supplemental plant oils to a high concentrate diet were investigated in vitro using RUSITEC (rumen simulation technique) fermenters. The control (CTR) diet was a high-concentrate total mixed ration for dairy sheep, with no supplementary oil. The other experimental diets were supplemented with olive (OLV), sunflower (SFL) or linseed (LNS) oils at 6% (dry matter basis). Four RUSITEC fermenters were used for each experimental diet, all inoculated with rumen digesta of sheep. Extent of dry matter and fat degradation, composition of the bacterial community and long-chain fatty acids in digesta were determined. The addition of plant oils increased (P < 0.001) apparent degradation of fat in the fermenters, whereas fermentation kinetics (gas production and average fermentation rate) were lower (P < 0.05) with the LNS than with the CTR diet. Hydrogenation of C18 unsaturated fatty acids (P < 0.05), in particular that of oleic acid (P < 0.001), and stearic acid proportion (P < 0.001) were reduced, and oleic acid proportion was increased (P < 0.001) with all oil supplements. Addition of OLV decreased linoleic and LNS increased α-linolenic (P < 0.001), whereas conjugated linoleic was increased with SFL oil (P = 0.025) and vaccenic increased with both SFL and LNS oils (P = 0.008). Addition of 6% OLV and LNS reduced (P < 0.05) microbial community diversity and quantity of total bacteria relative to the control. Some specific microbial groups were affected (P < 0.001) by oil addition, with less relative abundance of Clostridiales and Actinobacteria and increased Bacteroidales, Aeromonadales and Lactobacillales species. In conclusion, the supplementation of high-concentrate ruminant diets with plant oils, in particular from sunflower or linseed, causes shifts in the rumen microbiota and fatty acid hydrogenation in the rumen increasing the formation of vaccenic and conjugated linoleic acids.

Production of conjugated fatty acids: A review of recent advances

Conjugated fatty acids (CFAs) have received a deal of attention due to the increasing understanding of their beneficial physiological effects, especially the anti-cancer effects and metabolism-regulation activities. However, the production of CFAs is generally difficult. Several challenges are the low CFAs content in natural sources, the difficulty to chemically synthesize target CFA isomers in high purity, and the sensitive characteristics of CFAs. In this article, the current technologies to produce CFAs, including physical, chemical, and biotechnical approaches were summarized, with a focus on the conjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNAs) which are the most common investigated CFAs. CFAs usually demonstrate stronger physiological effects than other non-conjugated fatty acids; however, they are more sensitive to heat and oxidation. Consequently, the quality control throughout the entire production process of CFAs is significant. Special attention was given to the micro- or nano-encapsulation which presented as an emerging technique to improve the bioavailability and storage stability of CFAs. The current applications of CFAs and the potential research directions were also discussed.

Development of Commercially Viable Method of Conjugated Linoleic Acid Synthesis Using Linoleic Acid Fraction Obtained from Pork By-products

The purpose of this study was to develop a commercially viable method for synthesis of conjugated linoleic acid (CLA) using the linoleic acid fraction obtained from six pork by-products (liver, lung, heart, stomach, small intestine, and large intestine). The workflow of CLA synthesis from each by-product was as follows: washing→crude fat extraction→fractionation into saturated and unsaturated fatty acids→repeat unsaturated fatty acid fractionation→CLA synthesis. Cis-9, trans-11, and trans-10, cis-12 CLA was synthesized from pork by-products. The yield of CLA synthesis of pork by-products ranged from 1.55 to 11.18 g per 100 g of by-products. The amount of synthesized CLA was the highest in the small intestine and large intestine by-products. Fractionation of pork by-products nearly doubled the yield of CLA. We suggest that commercial fractionation methods could increase the yield of CLA at low cost, reduce waste, and improve the efficiency of by-product utilization.

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.

Nutritional enhancement of sheep meat fatty acid profile for human health and wellbeing

Dietary fatty acids (FA) consumed by sheep, like other ruminants, can undergo biohydrogenation resulting in high proportions of saturated FA (SFA) in meat. Biohydrogenation is typically less extensive in sheep than cattle, and consequently, sheep meat can contain higher proportions of omega (n)-3 polyunsaturated FA (PUFA), and PUFA biohydrogenation intermediates (PUFA-BHI) including conjugated linoleic acid (CLA) and trans-monounsaturated FAs (t-MUFA). Sheep meat is also noted for having characteristically higher contents of branched chain FA (BCFA). From a human health and wellness perspective, some SFA and trans-MUFA have been found to negatively affect blood lipid profiles, and are associated with increased risk of cardiovascular disease (CVD). On the other hand, n-3 PUFA, BCFA and some PUFA-BHI may have many potential beneficial effects on human health and wellbeing. In particular, vaccenic acid (VA), rumenic acid (RA) and BCFA may have potential for protecting against cancer and inflammatory disorders among other human health benefits. Several innovative strategies have been evaluated for their potential to enrich sheep meat with FA which may have human health benefits. To this end, dietary manipulation has been found to be the most effective strategy of improving the FA profile of sheep meat. However, there is a missing link between the FA profile of sheep meat, human consumption patterns of sheep FA and chronic diseases. The current review provides an overview of the nutritional strategies used to enhance the FA profile of sheep meat for human consumption.