Muscle Fatty Acid Research Articles

Effects of dietary arachidonic acid on the growth performance, feed utilization and fatty acid metabolism of Chinese mitten crab (Eriocheir sinensis)

A 12-week feeding trial was conducted to determine the effect of dietary arachidonic acid (ARA) levels on growth performance, feed utilization, muscle fatty acid composition and body proximate composition for juvenile Chinese mitten crab, Eriocheir sinensis. Six semi-purified diets containing 0.11% (control group, G1), 1.20% (G2), 2.37% (G3), 3.52% (G4), 4.76% (G5) and 7.39% (G6) ARA of total lipid content were formulated to feed six groups of crabs (the initial weight, 1.01 ± 0.12 g), respectively. Crabs in G3 showed the highest final weight, weight gain rate (WGR) and specific growth rate (SGR). The highest feed conversion ratio (FCR) was found in crabs in G1. In addition, the fatty acid composition of muscle was significantly affected by dietary ARA levels. For ARA, 22:2 and 20:5n-3, with the dietary ARA level increased, their contents increased first and then decreased, the highest values were all found in crabs of G4. High dietary ARA significantly affected the fatty acid composition of muscle in E. sinensis by increasing the relative expression of Srebp, while decreasing the relative expression of FAS, FAD 6 and ELOVL 6. Based on the results of the quadratic regression analysis of SGR and FCR, the optimum level of ARA for E. sinensis was suggested to be 4.54% and 3.88% of total lipid content, respectively.

Effects of Fat Type and Exogenous Bile Acids on Growth Performance, Nutrient Digestibility, Lipid Metabolism and Breast Muscle Fatty Acid Composition in Broiler Chickens.

Simple SummaryExogenous BAs can serve as emulsifiers and when supplemented in broiler chicken diets, they can facilitate the absorption of fat and fat-soluble nutrients. As far as we know, no research compared the impacts of BAs on broiler chickens fed with animal fat and vegetable oil. Therefore, the current research aimed to explore the impacts of fat type and BAs on growth performance, nutrient digestibility, lipid metabolism, and breast muscle fatty acids composition in broiler chickens. The results showed that the positive impacts of BAs were obvious for broiler chickens fed diets with lard compared with soybean oil.The current study aimed to explore the effects of fat type and exogenous bile acids (BAs) on growth performance, nutrient digestibility, lipid metabolism, and breast muscle fatty acids composition in broiler chickens. A total of 432 one-day-old Arbor Acres male broilers were stochastically distributed to a 2 × 2 factorial design comprised of two fat types (soybean oil and lard) and two levels of BAs (0 and 80 mg/kg) included in diets, totaling 4 treatments of 6 replicate pens with 18 chicks per replicate pen. Compared with treatments with soybean oil, dietary inclusion of lard increased the digestibility of ether extract (EE) in diets and the percentage of breast muscle on d 42, and increased the level of serum triglycerides and decreased serum alanine aminotransferase (ALT) activity on d 21 (p < 0.05). The level of saturated fatty acids, monounsaturated fatty acids (MUFAs), and the n-6 to n-3 polyunsaturated fatty acids ratio in breast muscle were also increased (p < 0.05) when feeding lard versus soybean oil. Dietary supplementation with BAs elevated average daily gain and reduced the ratio of feed to gain at d 0–21 and 0–42, significantly (p < 0.05). The digestibility of EE in diets and the percentage of breast muscle on d 42 were also increased by BAs (p < 0.05). Serum total cholesterol content as well as the percentage of abdominal fat on d 42, and ALT activity on d 21 were decreased when BAs were fed (p < 0.05). The concentration of total fatty acids, saturated fatty acids, and MUFAs of breast muscle were decreased by BAs. These results indicate that BAs can increase growth performance and nutrient digestibility, elevate carcass characteristics, and improve lipid metabolism, and their effects on nutrient digestibility and carcass characteristics were more pronounced in broiler chickens fed diets with lard.

Low n-6/n-3 Gestation and Lactation Diets Influence Early Performance, Muscle and Adipose Polyunsaturated Fatty Acid Content and Deposition, and Relative Abundance of Proteins in Suckling Piglets.

Elevated omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFAs) ratios in swine diets can potentially impose a higher risk of inflammatory and metabolic diseases in swine. A low ratio between the two omega PUFAs has beneficial effects on sows’ and piglets’ production performance and immunity status. At present, there are few studies on how sow nutrition directly affects the protein and fat deposition in suckling piglets. Two groups of sows were fed diets with high or low n-6/n-3 polyunsaturated ratios of 13:1 (SOY) and 4:1 (LIN), respectively, during gestation and lactation. Longissimus dorsi muscle and adipose tissue from newborn piglets, nourished only with sow’s milk, were subjected to fatty acid profiling by gas chromatography–mass spectrometry (GC-MS) and to proteomics assays based on nano-liquid chromatography coupled to high-resolution tandem mass spectrometry (nLC-HRMS). Fatty acid profiles on both muscle and adipose tissues resembled the magnitude of the differences between fatty acid across diets. Proteomic analysis revealed overabundance of 4 muscle and 11 adipose tissue proteins in SOY compared to LIN in both piglet tissues. The detected overabundance of haptoglobin, an acute-phase protein, and the stimulation of protein-coding genes and proteins related to the innate immune response and acute inflammatory response could be associated with the pro-inflammatory role of n-6 PUFAs.

Liver Fatty Acid‐Binding Protein (LFABP) Ablation Drives Hyperplastic Expansion of Subcutaneous Adipose Tissue in Male Mice Fed High‐Fat Diet

Liver fatty acid‐binding protein (LFABP) functions both in intracellular lipid trafficking in liver and small intestine, and in systemic energy homeostasis regulation. We found that despite the marked obesity of high fat‐fed LFABP null (LFABP‐/‐) mice compared to their wild‐type (WT) counterparts, they display a ‘metabolically healthy obese’ (MHO) phenotype characterized by normoglycemia and normoinsulinemia, increased spontaneous physical activity, and a resistance to high‐fat diet (HFD)‐induced decline in exercise capacity. They also display increased muscle fatty acid oxidation suggesting that adipose tissue lipolysis is enhanced. To gain insight into the effects of Lfabp ablation on the quality of adipose tissue, we determined the mass and cellularity of the inguinal (iWAT) and epididymal (eWAT) white adipose tissues.LFABP‐/‐ mice fed HFD for 12 weeks weighed 23.7% more (BW, g: 41.7 LFABP‐/‐ vs 33.7 WT, p=0.006, n=5) and their fat pads tended to be heavier (iWAT, g: 1.1 LFABP‐/‐ vs 0.8 WT, p=0.060, n=5; eWAT, g: 1.4 LFABP‐/‐ vs 1.8 WT, p=0.065, n=5). Intriguingly, as shown in Figure 1, adipocyte size of iWAT adipocytes is smaller than that of the WT mice (44.6pL LFABP‐/‐ vs 188.1pL WT per cell, p=0.009, n=5). Adipocyte number was substantially increased in the iWAT of LFABP‐/‐ (23.6 LFABP‐/‐ vs 4.6 WT x 106, p=0.001, n=5). In contrast, the eWAT adipocyte size in the LFABP‐/‐ is comparable to WT (210pL LFABP‐/‐ vs 268 pL WT per cell, p=0.293, n=5), and eWAT fat cell number was highly variable and trended higher in the LFABP‐/‐ mice (9.8 LFABP‐/‐ vs 4.7 WT x 106, p=0.059, n=5).Because LFABP is not expressed in adipose tissue, our data suggest that its ablation promotes interorgan signaling that may limit hypertrophy and drive hyperplasia in expansion of potentially metabolically beneficial subcutaneous iWAT. More studies are warranted to elucidate the marked differences in cell size and the apparent depot‐dependent effects of LFABP‐/‐ deficiency, as well as the mechanisms by which it modulates adipocyte growth and function.

Muscle Fatty Acids, Meat Flavor Compounds and Sensory Characteristics of Xiangxi Yellow Cattle in Comparison to Aberdeen Angus.

Simple SummaryWith agricultural mechanization and the increasing demand for meat, Xiangxi yellow cattle are increasingly being raised for meat production. Little is known about the changes in muscle composition and eating quality of the cattle at different ages. In the present study, the muscle proximate composition, meat flavor substances, and sensory quality of Xiangxi yellow cattle at different growth stages were profiled in comparison to Aberdeen Angus cattle, which may provide valuable information for high grade beef production from Xiangxi yellow cattle. This study showed that Xiangxi yellow cattle is a fine cattle breed with equal or even better meat quality attributes when compared to Angus. It is proper to slaughter Xiangxi yellow cattle at the age of 18 months for high quality beef production.The objective of this study was to investigate meat quality of Xiangxi yellow cattle of different ages in comparison to Aberdeen Angus. At the ages of 6, 18, and 30 months, 10 female animals for both Xiangxi yellow cattle and Aberdeen Angus cattle were randomly selected and slaughtered. The proximate composition analysis, fatty acid profiles and flavor compounds were measured on the longissimus thoracis (LT) muscle samples. One boneless loin chop was dissected and used for sensory evaluation by a 10-persoon trained taste panel. The data obtained showed that Xiangxi yellow cattle deposited similarly high level of intramuscular fat as Angus at the age of 18 month and the polyunsaturated fatty acid in muscle along with the PUFA/SFA ratio reached the highest levels at this age. Inosine 5′-monophosphate (IMP) was the predominant umami compound in beef, which concentration was significantly higher (p < 0.05) at month 18, but not different between Angus and Xiangxi yellow cattle. Multiple volatile flavor compounds were higher (p < 0.05) in concentrations in meat from Xiangxi yellow cattle at ages of 18 and 30 months when compared to Angus. Sensory analysis revealed that Xiangxi yellow cattle (18 and 30 months) and Angus (30 months) were superior in meat overall eating quality to Xiangxi yellow cattle (6 months) and Angus (6 and 18 months). This study showed that Xiangxi yellow cattle are a fine cattle breed with equal or even better meat quality attributes when compared to Angus. It is proper to slaughter Xiangxi yellow cattle at the age of 18 months for high quality beef production.

Evaluation of Nannochloropsis gaditana raw and hydrolysed biomass at low inclusion level as dietary functional additive for gilthead seabream (Sparus aurata) juveniles

Abundant research is being carried out in the last years aimed at exploring microalgal biomass as nutrient source for different species of aquacultured fish. Some microalgae species, such as Nannochloropsis gaditana, have thick cell walls rich in cellulose, which might well reduce the bioavailability of intracellular active compounds. Among the alternatives aimed at overcoming this limitation, cellulase enzyme hydrolysis is proposed as a convenient and practical solution. In this regard, an in vitro assay was carried out, in which N. gaditana biomass was treated with cellulase (5% w/w basis) and the release of soluble compounds (reducing sugars, free amino acids and total phenolics) into the reaction medium was measured and compared to untreated raw biomass. The results confirmed increased yields of those compounds as a result of the enzyme pre-treatment. A 90-d feeding trial was also carried out in order to assess in vivo the influence of the inclusion of N. gaditana in feeds on juvenile gilthead seabream (Sparus aurata) growth, digestive physiology and body composition. Microalgal biomass was added at two inclusion levels (25 and 50 g kg−1 dry weight) in four experimental feeds, either crude or enzymatically pre-treated. Animals (15.1 g initial body weight) were randomly assigned to five dietary treatments (two inclusion levels, 2.5 and 5%, and two microalgae formats, raw and enzymatically hydrolysed, plus a microalgae-free control), and distributed triplicate tanks per dietary treatment. Fish were withdrawn after 45 and 90 days, and proximate composition, muscle fatty acid and amino acid profiles, muscle and liver lipid oxidation, instrumental skin colour, digestive enzyme activities, as well as structural and ultrastructural changes in the intestinal mucosa were determined. No differences attributable to the dietary treatments were found with regard to fish growth or proximate composition at the end of the feeding trial. On the contrary, the inclusion of microalgal biomass, irrespectively of the cellulase pre-treatment, caused beneficial effects on some physiological parameters (namely digestive mucosa structure and functionality, oxidative status of muscle lipids, and instrumental colour). The only clear improvement found in fish attributable to the cellulase pre-treatment of the microalgal biomass was related to the prevention of muscle lipid oxidation. Overall, the results suggest that N. gaditana used as additive (at inclusion level below 5%) in feeds might represent a valuable nutritional strategy for S. aurata juveniles, even if growth was not affected.

Genetic parameters of fillet fatty acids and fat deposition in gilthead seabream (Sparus aurata) using the novel 30 k Medfish SNP array

Lipid-related traits are important candidates for a breeding goal for gilthead seabream, because they affect both fish and human health, as well as production efficiency. However, to date there have been very few estimates of genetic parameters for these traits, and the genetic relationship between fatty acids and other important traits have never been reported for gilthead seabream. Therefore, the aim of this study was to estimate genomic heritability and genetic relationships of fat deposition traits and individual muscle fatty acids in a commercial population of gilthead seabream using the novel ~30 k MedFish SNP array.In total 967 gilthead seabream fed with a commercial feed were genotyped with the MedFish SNP chip which included ~30 K informative markers for this species. On average, the fish weighed 372 g. The mean content of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) was 822 mg per 100 g fillet. The heritability of muscle fat, viscera weight and percentage viscera were in the range of 0.34–0.46. The genetic correlation of body weight with muscle fat was 0.12, indicating that genetic variation in muscle fat is largely independent of the weight of the fish. The heritability of the product of endogenous fatty acid synthesis (n = 240), palmitoleic acid (16:1n-7), was high (0.43). The estimated heritability of EPA (%) and DHA (%) was 0.39 and 0.33, respectively. Both EPA and DHA had low, non-significant genetic correlations with body weight, and DHA had a negative genetic correlation with muscle fat (−0.53).It is possible to increase EPA and DHA content in gilthead seabream fillets by selective breeding. The high heritability of 16:1n-7, a marker of de novo lipogenesis, suggests that there is a strong genetic component to this metabolic pathway in gilthead seabream. Muscle fat deposition and body weight seem to be independent traits, and selective breeding for faster growth is not likely to influence the proportional content of EPA and DHA.

Comparison of Muscle Quality of the Yellow Catfish Cultured in In-Pond Raceway Systems and Traditional Ponds

In order to understand the difference in muscle nutritional quality between yellow catfish (Pelteobagrus fulvidraco) cultured in in-pond raceway systems (IPR) and traditional ponds (TRP), two modes were used to culture the yellow catfish with the same initial body weight [average body weight (15.69 1 ± 2.28) g] for 60 days. The growth index, muscle texture characteristics, muscle nutritional components, amino acids and fatty acids of the fish were measured after the culture experiment. The results showed that the weight gain rate, specific growth rate and survival rate of IPR were significantly higher than TRP (p &lt; 0.05). The hardness, elasticity, chewiness and resilience of the yellow catfish cultured in IPR were significantly higher than those cultured in TRP (p &lt; 0.05). The crude protein content in the muscle of the yellow catfish cultured in IPR was significantly higher than that cultured in TRP (p &lt; 0.01), while the content of crude fat and water was significantly lower (p &lt; 0.01). The total amount of amino acids, essential amino acids and flavor amino acids of IPR were significantly higher than TRP (p &lt; 0.01). The percentages of saturated fatty acids in muscle of the yellow catfish cultured in IPR and TRP were 3.59% and 3.83%, respectively, and the percentages of unsaturated fatty acids were 96.41% and 96.17%, respectively. It was concluded that the nutritional quality of yellow catfish cultured in IPR was better than that of fish cultured in TRP.

Integrative Analysis of Nanopore and Illumina Sequencing Reveals Alternative Splicing Complexity in Pig Longissimus Dorsi Muscle.

Alternative splicing (AS) is a key step in the post-transcriptional regulation of gene expression that can affect intramuscular fat (IMF). In this study, longissimus dorsi muscles from 30 pigs in high- and low- IMF groups were used to perform Oxford Nanopore Technologies (ONT) full-length sequencing and Illumina strand-specific RNA-seq. A total of 43,688 full-length transcripts were identified, with 4,322 novel genes and 30,795 novel transcripts. Using AStalavista, a total of 14,728 AS events were detected in the longissimus dorsi muscle. About 17.79% of the genes produced splicing isoforms, in which exon skipping was the most frequent AS event. By analyzing the expression differences of mRNAs and splicing isoforms, we found that differentially expressed mRNAs with splicing isoforms could participate in skeletal muscle development and fatty acid metabolism, which might determine muscle-related traits. SERBP1, MYL1, TNNT3, and TNNT1 were identified with multiple splicing isoforms, with significant differences in expression. AS events occurring in IFI6 and GADD45G may cause significant differences in gene expression. Other AS events, such as ONT.15153.3, may regulate the function of ART1 by regulating the expression of different transcripts. Moreover, co-expression and protein-protein interaction (PPI) analysis indicated that several genes (MRPL27, AAR2, PYGM, PSMD4, SCNM1, and HNRNPDL) may be related to intramuscular fat. The splicing isoforms investigated in our research provide a reference for the study of alternative splicing regulation of intramuscular fat deposition.

Evaluation of two types of ingredients from marine fish rest raw materials in broiler diets: effects on live performance and meat lipid composition

The current study investigated the effect of incorporating two ingredients derived from different types of marine fish rest raw materials in the diet of broiler chickens on live performance, carcass yield, muscle fatty acid ( FA ) composition, lipid peroxidation products, and blood metabolites. A total of ninety (n = 90), one-day-old Cobb chicks were fed a corn-soybean meal-based diet with no marine rest raw material ( Control ), 5% deboned Pacific hake meal ( Diet 1 ), or 5% Pacific surimi washwater meal ( Diet 2 ) for 42 d (30 birds per treatment kept in 6 replicate pens with 5 chicks per pen). For bird performance (feed consumption, weight gain), each replicate pen was considered as the experimental unit. For determining yield, blood metabolites, and lipid analysis, one bird collected from each replicate is considered as the experimental unit. Bodyweight gain and feed:gain were determined at the starter (1–10), grower (11–21), and finisher (22–42) phases. For all response variables, the effects of Control vs. Diet 1 and Diet 2 were compared separately using analysis of variance. P values were considered significant at ≤0.05. No difference was observed in the body weight gain and feed:gain at day 10 ( P > 0.05). At day 21, Diet 1 and Diet 2 birds were higher in body weight than Control ( P < 0.05). At day 42, Diet 1 birds were highest in body weight (3,018 g) when compared to Control (2,728 g) ( P < 0.05) and was not different from Diet 2 (2,912 g) ( P > 0.05). Overall, feed:gain was lowest in Diet 2 (1.52) ( P < 0.05) and was not different from Diet 1. A 2 to 5-fold increase in n-3 FA was observed in the breast and thigh muscle of Diet 1 and Diet 2 compared to Control ( P < 0.05). Docosahexaenoic acid ( DHA , 22:6 n-3) was the major long chain FA in the breast and thigh muscle and addition of marine rest raw material led to >10-fold increase in the breast and thigh muscle DHA in Diet 1 and Diet 2 when compared to Control ( P < 0.05). The total lipid content of thigh muscle was lower in Diet 1 and Diet 2 compared to Control ( P < 0.05). No difference was observed in the total lipid content of breast muscle ( P > 0.05). The relative organ weight and yield of breast and thigh muscles were not different among the three treatments ( P > 0.05). No difference was observed in moisture and cholesterol content in breast and thigh muscles ( P > 0.05). Blood cholesterol was lower in Diet 1 than Control ( P < 0.05). Lipid peroxidation products measured as thiobarbituric acid reactive substances ( TBARS ) were lower in the breast muscle of Diet 1 and Diet 2 compared to Control ( P < 0.05). However, no effect of diet on thigh muscle TBARS was observed ( P > 0.05). As consumer demands for n-3 FA-rich poultry products are on the rise, products derived from marine rest raw materials may serve as feed supplement that could be used in broiler chicken diets for enriching edible tissues with n-3 FA while increasing bird live performance and promoting ecological poultry production.

Increased Expression of Syncytin-1 in Skeletal Muscle of Humans With Increased Body Mass Index.

Obesity negatively impacts skeletal muscle protein metabolism, and also impairs skeletal muscle maintenance and regeneration. We analyzed muscle biopsy samples from humans with increased body mass index (BMI) (i.e. > 30 kg/m2) and controls (i.e., BMI < 25 kg/m2) for expression of syncytin-1, a fusogenic protein regulating skeletal muscle regeneration. When compared to controls, humans with increased BMI and concomitant reduction in muscle protein synthesis had higher expression of syncytin-1 in skeletal muscle (p < 0.05). Across human subjects, muscle protein synthesis correlated inversely (r = −0.51; p = 0.03) with syncytin-1 expression in muscle. Using a C2C12 cell line we found that expression of syncytin-A (i.e, corresponding protein in murine tissue) is increased by insulin, and that this response is impaired in the presence of fatty acids, whose metabolism is altered within the metabolic environment induced by increased BMI. In C2C12 cells, the response of the protein 4E-BP1, which signals increase in protein synthesis in muscle, resembled that of syncytin-A. These findings provide novel insights into the expression of syncytin-1 in skeletal muscle of humans with increased BMI, as well as its basic regulation by insulin and fatty acids in muscle. The findings signify the need for further research into the regulation of syncytin-1 in skeletal muscle of humans with increased BMI, as well as its biological implications for altering muscle protein metabolism and regeneration.

Lipotoxic Effects of Gossypol Acetate Supplementation on Hepatopancreas Fat Accumulation and Fatty Acid Profile in Cyprinus carpio

Cottonseed meal is an excellent protein source with low price and abundant nutrients, but the existence of free gossypol restricts its wide application in animal feeds. To explore the toxic effects of free gossypol, the effects of gossypol acetate on the growth performance, hepatopancreatic fat accumulation, and muscle fatty acid composition of the common carp (Cyprinus carpio) were investigated in the present study. Carp were randomly divided into four groups, which were fed a diet supplemented with 0, 170, 340, and 680 mg/kg gossypol acetate, respectively. After 60 days of feeding, the gossypol residue in the tissue, growth performance, blood biochemical indices, hepatopancreas histology, fatty acid components, and expression of key genes involved in lipid metabolism pathways were measured. It was found that the concentrations of free gossypol were increased significantly in the serum, bile, and hepatopancreas of carp fed 340 mg/kg and 680 mg/kg gossypol acetate ( P &lt; 0.05 ). Dietary gossypol acetate had a limited effect on growth performance, and high concentrations of gossypol acetate induced excessive hepatopancreatic fat deposition and hepatocyte injury in C. carpio. In addition, gossypol acetate decreased total polyunsaturated fatty acids (PUFAs) and docosahexaenoic acid in muscle. In the hepatopancreas, decreased HSL, PPARα, and CD36 may result in fat accumulation. In the muscle, decreased FADS2 may be the key reason for the decrease in PUFAs. Taken together, these findings indicated that dietary gossypol acetate can cause lipid metabolism disorders, such as hepatopancreatic damage and significant changes in tissue fatty acid profile, which are regulated by the key lipid metabolic genes in common carp.

Leptin Receptor Deficiency Results in Hyperphagia and Increased Fatty Acid Mobilization during Fasting in Rainbow Trout (Oncorhynchus mykiss).

Leptin is a pleiotropic hormone known for regulating appetite and metabolism. To characterize the role of leptin signaling in rainbow trout, we used CRISPR/Cas9 genome editing to disrupt the leptin receptor (LepR) genes, lepra1 and lepra2. We compared wildtype (WT) and mutant fish that were either fed to satiation or feed deprived for six weeks. The LepR mutants exhibited a hyperphagic phenotype, which led to heavier body weight, faster specific growth rate, increased viscero- and hepatosomatic indices, and greater condition factor. Muscle glycogen, plasma leptin, and leptin transcripts (lepa1) were also elevated in fed LepR mutant fish. Expression levels of several hypothalamic genes involved in feed regulation were analyzed (agrp, npy, orexin, cart-1, cart-2, pomc-a1, pomc-b). No differences were detected between fed WT and mutants except for pomc-b (proopiomelanocortin-b), where levels were 7.5-fold higher in LepR fed mutants, suggesting that pomc-b expression is regulated by leptin signaling. Fatty acid (FA) content did not statistically differ in muscle of fed mutant fish compared to WT. However, fasted mutants exhibited significantly lower muscle FA concentrations, suggesting that LepR mutants exhibit increased FA mobilization during fasting. These data demonstrate a key role for leptin signaling in lipid and energy mobilization in a teleost fish.

Raman and near Infrared Spectroscopy for Quantification of Fatty Acids in Muscle Tissue-A Salmon Case Study.

The aim of the present study was to critically evaluate the potential of using NIR and Raman spectroscopy for prediction of fatty acid features and single fatty acids in salmon muscle. The study was based on 618 homogenized salmon muscle samples acquired from Atlantic salmon representing a one year-class nucleus, fed the same high fish oil feed. NIR and Raman spectra were used to make regression models for fatty acid features and single fatty acids measured by gas chromatography. The predictive performance of both NIR and Raman was good for most fatty acids, with R2 above 0.6. Overall, Raman performed marginally better than NIR, and since the Raman models generally required fewer components than respective NIR models to reach high and optimal performance, Raman is likely more robust for measuring fatty acids compared to NIR. The fatty acids of the salmon samples co-varied to a large extent, a feature that was exacerbated by the overlapping peaks in NIR and Raman spectra. Thus, the fatty acid related variation of the spectroscopic data of the present study can be explained by only a few independent principal components. For the Raman spectra, this variation was dominated by functional groups originating from long-chain polyunsaturated FAs like EPA and DHA. By exploring the independent EPA and DHA Raman models, spectral signatures similar to the respective pure fatty acids could be seen. This proves the potential of Raman spectroscopy for single fatty acid prediction in muscle tissue.

Dietary Plukenetia conophora seed alters muscle cholesterol, antioxidant enzymes, and fatty acids in growing rabbits

The influence of dietary inclusion of Plukenetia conophora seed (PCS) on growth, carcass, muscle antioxidant enzymes, fatty acids, meat quality, and sensory attributes of Longissimus thoracis et lumburum muscle in rabbits was examined. Seventy-two, 28 d old male New Zealand rabbits (750 ± 20 g) were randomly allotted to diets containing either no PCS (PCS-0), 2.5% PCS (PCS-2.5) or 5% PCS (PCS-5) for eight weeks, and euthanized. PCS-5 rabbits had higher (P < 0.05) body and carcass weights than the PCS-0 rabbits. Dietary PCS improved feed efficiency in rabbits. Muscle antioxidant enzymes activities and total phenols were higher while muscle cholesterol was lower (P < 0.05) in supplemented meat than the PCS-0 meat. The concentration of C22:6n-3, C20:5n-3 and C18:3n-3 was higher (P < 0.05) in the supplemented meat than the PCS-0 meat. Sensory attributes, carbonyl, and TBARS values and physicochemical properties of meat did not differ among diets. Supplementation of PCS-5 enhances muscle n-3 fatty acids without impairing the sensory properties, and oxidative stability of rabbit meat.

Response of lipid-related composition of farmed tiger puffer (Takifugu rubripes) to starvation under different dietary lipid levels in the previous feeding period

Starvation is a natural process in the life cycle of wild fish, and also a means of body composition regulation for farmed fish. This study with tiger puffer was aimed at investigating the effects of starvation on lipid and fatty acid compositions in fish with different levels of lipid accumulation. Different lipid accumulation levels in tiger puffer were obtained by manipulating the dietary lipid content (8%, 12%, and 16%) in a previous feeding period for 9 weeks. Each diet was fed to sextuplicate net cages in this feeding trial. At the end of the feeding trial, fish with an average initial body weight of 68.26 g were then subjected to starvation for 31 days. Tissue samples were collected at the end of the feeding trial and at 1, 4, 9, 16, and 31 days after starvation. The results showed that the muscle lipid content decreased linearly with starvation time, but the liver lipid content increased firstly (1–16 days of starvation), and thereafter sharply declined. However, no interaction between starvation time and dietary lipid level was observed in the effects on liver and muscle lipid composition. Starvation had slight effects on muscle and liver fatty acid compositions, except that it largely increased the C22:5n-3 content in the muscle. Starvation primarily mobilized C14:0, C16:1n-7, C20:1n-9 and C22:1n-9 in the muscle, and C18:0, C18:1n-9, and EPA in the liver. Interactive effects between starvation time and dietary lipid level were observed for many fatty acids. Short-term (1–4 days) starvation increased the muscle texture parameters, but longer-term starvation decreased them. In conclusion, starvation exerts significant effects on lipid and fatty acid composition in farmed tiger puffer. Customed lipid and fatty acid composition, and possibly customed fillet quality could be obtained through manipulation of starvation time and dietary lipid level in the previous feeding period.

Dietary lysophosphatidylcholine regulates diacylglycerol, cardiolipin and free fatty acid contents in the fillet of turbot.

Lysophosphatidylcholine (LPC) has been widely used as emulsifier in animal feeds to enhance the lipid utilization. However, the effects of LPC on fillet quality has rarely been known. The present study was the first time to investigate the response of fish muscle lipidomics to dietary LPC supplementation. Turbot muscle samples were collected after a 56-day feeding trial where the experimental diet contained 0 or 0.25% LPC. Targeted tandem mass spectrometry was used in the lipidomic analysis. A total of 62 individual lipids (58 up-regulated and 7 down-regulated by LPC) showed significant difference in concentration in response to dietary LPC. Most of these differentially abundant lipids were diacylglycerol, free fatty acid and cardiolipin, and they all were up-regulated by dietary LPC. However, LPC exerted only marginal effects on muscle fatty acid composition and lipid content. The effects of dietary LPC on fillet lipid composition cannot be neglected in fish product evaluation.

The effects of diet and chronic exercise on skeletal muscle ghrelin response

BackgroundRecent findings indicate that ghrelin, particularly the unacylated form (UnAG), acutely stimulates skeletal muscle fatty acid oxidation (FAO) and can preserve insulin signaling and insulin-stimulated glucose uptake in the presence of high concentrations of saturated fatty acids. However, we recently reported that the stimulatory effect of ghrelin on FAO and subsequent ability to protect insulin stimulated glucose uptake was lost following 6-weeks (6w) of chronic high fat feeding. In the current study we examined the effects of both short-term 5 day (5d) and chronic 6w high-fat diet (HFD) on muscle ghrelin response, and whether exercise training could prevent the development of muscle ghrelin resistance with 6w of HFD Methods and ResultsSoleus muscle strips were isolated from male rats to determine the direct effects of acylated (AG) and UnAG isoforms on FAO and glucose uptake. A 5d HFD did not alter the response of soleus muscle to AG or UnAG. Conversely, 6w of HFD was associated with a loss of ghrelin's ability to stimulate FAO and protect insulin stimulated glucose uptake. Muscle response to UnAG remained intact following the 6w HFD with chronic exercise training. Unexpectedly, muscle response to both AG and UnAG was also lost after 6w of low-fat diet (LFD) consumption. Protein content of the classic ghrelin receptor, GHS-R1a, was not affected by diet or training. Corticotropin-releasing hormone receptor-2 (CRF-2R) content, a putative receptor for ghrelin in muscle, was significantly decreased in soleus from 6w HFD-fed animals and increased following exercise training. This may explain the protection of UnAG response with training in HFD-fed rats but does not explain why ghrelin response was also lost in LFD-fed animals. ConclusionsUnAG protects muscle glucose uptake during acute lipid oversupply, likely due to its ability to stimulate FAO. This effect is lost in 6w HFD-fed animals but protected with exercise training. Unexpectedly, ghrelin response was lost in 6w LFD-fed animals. The loss of ghrelin response in muscle with a LFD cannot be explained by a change in putative ghrelin receptor content. We believe that the sedentary nature of the animals is a major factor in the development of muscle ghrelin resistance and warrants further research.

Comprehensive Transcriptome Analysis Reveals the Role of lncRNA in Fatty Acid Metabolism in the Longissimus Thoracis Muscle of Tibetan Sheep at Different Ages.

Long noncoding RNA (lncRNA) plays an important regulatory role in mammalian adipogenesis and lipid metabolism. However, their function in the longissimus thoracis (LT) muscle of fatty acid metabolism of Tibetan sheep remains undefined. In this study, fatty acid and fat content in LT muscle of Tibetan sheep were determined, and RNA sequencing was performed to reveal the temporal regularity of lncRNA expression and the effect of lncRNA-miRNA-mRNA ceRNA regulatory network on lipid metabolism of LT muscle in Tibetan sheep at four growth stages (4-month-old, 4 m; 1.5-year-old, 1.5 y; 3.5-year-old, 3.5 y; 6-year-old, 6 y). The results indicated that the intramuscular fat (IMF) content was highest at 1.5 y. Moreover, the monounsaturated fatty acid (MUFA) content in 1.5 y of Tibetan sheep is significantly higher than those of the other groups (P < 0.05), and it was also rich in a variety of polyunsaturated fatty acids (PUFA). A total of 360 differentially expressed lncRNAs (DE lncRNAs) were identified from contiguous period transcriptome comparative groups of 4 m vs. 1.5 y, 1.5 y vs. 3.5 y, 3.5 y vs. 6 y, and 4 m vs. 6 y, respectively. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis found that the target genes in lncRNA trans-mRNA were significantly related to the protein digestion, absorption, and fatty acid biosynthesis pathways (P < 0.05), which demonstrated that DE lncRNA trans-regulated the target genes, and further regulated the growth and development of the LT muscle and intramuscular fatty acid metabolism in Tibetan sheep. We further analyzed the role of the lncRNA-miRNA-mRNA regulatory network in the lipid metabolism of Tibetan sheep. Additionally, GPD2, LIPE (lipase E hormone-sensitive enzyme), TFDP2, CPT1A, ACACB, ADIPOQ, and other mRNA related to fatty acid and lipid metabolism and the corresponding lncRNA-miRNA regulatory pairs were identified. The enrichment analysis of mRNA in the regulatory network found that the AMPK signaling pathway was the most significantly enriched (P = 0.0000112361). Comprehensive transcriptome analysis found that the LIPE, ADIPOQ, ACACB, and CPT1A that were regulated by lncRNA might change the formation of energy metabolism in Tibetan sheep muscle through the AMPK signaling pathway, and oxidized muscle fibers are transformed into glycolytic muscle fibers, reduced IMF content, and the fatty acid profile also changed.

Impact of Dietary Docosahexaenoic Acid : Eicosapentaenoic Acid Ratio on Growth, Fatty Acid Composition, Lipid Metabolism, and Antioxidant Status of Juvenile Hybrid Grouper (Brown‐marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♂)

AbstractThe present study was conducted to evaluate the effects of dietary docosahexaenoic acid : eicosapentaenoic acid (DHA:EPA) ratio on growth, lipid metabolism, and antioxidant status of hybrid grouper (Brown‐marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♀). Fish (initial body weight = 20.8 ± 0.03 g; mean ± SE) were fed six different isoproteic (53%) and isolipidic (7%) diets containing graded DHA:EPA ratios (D/E) of 0.54, 0.97, 1.51, 2.01, 2.41, and 2.85. No significant difference in weight gain was recorded in fish fed with different dietary DHA:EPA ratios. The DHA:EPA ratio in fish muscle was significantly increased as the dietary ratio increased. Relative messenger RNA expression of hepatic elongase of very long fatty acids 5 (elovl5*) and delta‐6 fatty acyl desaturase (Δ6 fad*) in the D/E 2.41 and 2.85 groups was significantly higher than that in the other treatments. Lipid droplet accumulation was significantly higher in the liver of the D/E 0.54 and 0.97 groups than in the other groups. Lipogenesis‐related genes (fatty acid synthase [FAS*] and acetyl coenzyme A carboxylase [ACC*]) were up‐regulated by lower dietary DHA:EPA ratios (0.54 and 0.97), whereas lipolysis‐related genes (peroxisome proliferator‐activated receptor alpha [PPARα*] and hormone‐sensitive lipase [HSL*]) were down‐regulated. The expression of genes related to antioxidative capacity, including nuclear factor erythroid 2‐related factor 2 (Nrf2*), manganese superoxide dismutase (MnSOD*), and peroxiredoxin (Prx*), was significantly down‐regulated in the D/E 1.51 and 2.01 groups compared with other treatments, while Kelch‐like ECH‐associated protein 1 (Keap1*) was up‐regulated. The above results suggest that dietary DHA:EPA ratio influences muscle fatty acid composition and lipid metabolism by altering the expression of lipogenesis‐ and lipolysis‐related genes, and dietary DHA:EPA ratio may also regulate the antioxidant capacity of juvenile hybrid grouper.