Tissue fatty acid composition of pigs fed different fat sources

Dietary fat influences the physico-chemical properties of meat, and fatty acid (FA) composition may have implications on human health. The objectives of the experiment were to study tissue FA partitioning and the effect of dietary fat source on tissue FA composition. Seventy crossbred gilts (61.8 ± 5.2 kg BW average) were fed one of seven treatments: a diet containing a very low level of fat (no fat (NF)) and six fat-supplemented diets (10%: tallow (T), high-oleic sunflower oil (HOSF), sunflower oil (SFO), linseed oil (LO), fat blend (FB: 55% tallow, 35% SFO, 10% LO) and fish oil blend (FO: 40% fish oil, 60% LO). Differential tissue FA depositions were observed, with flare fat being the most saturated, followed by intermuscular, and subcutaneous being the least saturated. Monounsaturated fatty acid (MUFA) deposition showed an opposite tissue pattern. Subcutaneous fat showed the highest MUFAs, intermuscular fat showed intermediate values and flare fat showed the lowest MUFAs. Intramuscular polyunsaturated fatty acid (PUFA) content was less susceptible to dietary treatment modifications compared with other depots. Significant tissue FA modifications were observed due to dietary treatments, mainly in diets rich in PUFA. The saturated fatty acids (SFA) were high in NF-fed and low in HOSF-fed animals, MUFA were high in HOSF-fed and low in SFO-, LO- and FO-fed animals, while PUFA were high in SFO- and LO-fed and low in HOSF-, T- and NF-fed animals. Pigs fed LO and FB showed detectable levels of EPA, which depended on the linolenic content of the diet. The only effective way to increase tissue DHA contents was to add DHA in the diet through FO feeding. Araquidonic acid was high in SFO diets and low in LO and FB diets, and also high in intramuscular fat compared with other tissues. EPA and DHA were also high in intramuscular fat compared with other fat depots. The deposition of oleic and linoleic acids depended on the composition of dietary fat, as their deposition varied between diets, even at similar levels of intake of each FA. The NF diet resulted in the greatest proportion of SFAs (palmitic and stearic) of all treatments tested. SFAs were less susceptible to modification than MUFA in response to the different PUFA levels supplemented in the diet. T resulted in less fat deposition in some of the fat depots and more in others, suggesting that T could partition fat differently among fat depots.     

Developmental changes and effect on intramuscular fat content of H-FABP and A-FABP mRNA expression in pigs

H-FABP and A-FABP genes are considered as candidates for intramuscular fat (IMF) accretion. The aim of the present study was to assess the expression of H-FABP and A-FABP genes in m. longissimus dorsi (LD) and liver tissues of Laiwu and Lulai Black pig populations of different body weight (BW). Eighty-four barrows at different BW (30, 40, 50, 60, 70, 80, 90 and 100 kg, n?=?6 per group) of Laiwu Black pig (no 100 kg group) and Lulai Black pig (no 30 kg group) were used to study the development changes of A-FABP and H-FABP mRNA expression and their relationships to IMF content. The results showed that, in both breeds, the IMF content increased continuously with growing (P?<?0.05). The expression of H-FABP and A-FABP genes also increased with growing in LD tissue (P?<?0.05), and reached a peak at 50 and 70 kg BW in Laiwu and Lulai Black pig, respectively. However, this regularity was not observed in liver tissue in both breeds. A positive correlation was just found between the A-FABP mRNA expression level in LD tissue and IMF content and BW in both breeds (P?<?0.05). In conclusion, the A-FABP gene is strongly related to the development and function of IMF accretion in pigs.     

Effect of selection for intramuscular fat on the fatty acid composition of rabbit meat

Intramuscular fat (IMF) content and composition are relevant for the meat industry due to their effect on human health and meat organoleptic properties. A divergent selection experiment for IMF of Longissimus dorsi (LD) muscle was performed in rabbits during eight generations. The aim of this study is to estimate the correlated responses to selection for IMF on the fatty acid composition of LD. Response to selection for IMF was 0.34 g/100 g of LD, representing 2.4 phenotypic SD of the trait. High-IMF line showed 9.20% more monounsaturated fatty acids (MUFA) and 0.39%, 9.97% and 10.3% less n-3, n-6 and polyunsaturated fatty acids (PUFA), respectively, than low-IMF line. The main MUFA and PUFA individual fatty acids followed a similar pattern, except for C18:3n-3 that was greater in the high-IMF line. We did not observe differences between lines for the percentage of total saturated fatty acids, although high-IMF line showed greater C14:0 and C16:0 and lower C18:0 percentages than low-IMF line. Heritability estimates were generally high for all fatty acids percentages, ranging from 0.43 to 0.59 with a SD around 0.08, showing an important genetic component on these traits. Genetic correlations between IMF and LD fatty acid percentages were strong and positive for C14:0, C16:1, C18:1n-9, and MUFA, ranging from 0.88 to 0.97, and strong and negative for C18:0, C18:2n-6, C20:4n-6, n-6 and PUFA, ranging from −0.83 to −0.91. These correlations were accurately estimated, with SD ranging from 0.02 to 0.06. The genetic correlations between IMF and other fatty acids were estimated with lower accuracy. In general, phenotypic and genetic correlations were of the same order. Our experiment shows that selection for IMF strongly affects the fatty acid composition of meat, due the high heritabilities of fatty acids and their high genetic correlations with IMF.     

Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds

Acyl–acyl carrier protein (ACP) thioesterases are enzymes that control the termination of intraplastidial fatty acid synthesis by hydrolyzing the acyl–ACP complexes. Among the different thioesterase gene families found in plants, the FatA-type fulfills a fundamental role in the export of the C18 fatty acid moieties that will be used to synthesize most plant glycerolipids. A reverse genomic approach has been used to study the FatA thioesterase in seed oil accumulation by screening different mutant collections of Arabidopsis thaliana for FatA knockouts. Two mutants were identified with T-DNA insertions in the promoter region of each of the two copies of FatA present in the Arabidopsis genome, from which a double FatA Arabidopsis mutant was made. The expression of both forms of FatA thioesterases was reduced in this double mutant (fata1 fata2), as was FatA activity. This decrease did not cause any evident morphological changes in the mutant plants, although the partial reduction of this activity affected the oil content and fatty acid composition of the Arabidopsis seeds. Thus, dry mutant seeds had less triacylglycerol content, while other neutral lipids like diacylglycerols were not affected. Furthermore, the metabolic flow of the different glycerolipid species into seed oil in the developing seeds was reduced at different stages of seed formation in the fata1 fata2 line. This diminished metabolic flow induced increases in the proportion of linolenic and erucic fatty acids in the seed oil, in a similar way as previously reported for the wri1 Arabidopsis mutant that accumulates oil poorly. The similarities between these two mutants and the origin of their phenotype are discussed in function of the results.     

Nitrogen deficiency in Arabidopsis affects galactolipid composition and gene expression and results in accumulation of fatty acid phytyl esters

Nitrogen is an essential nutrient for plants because it represents a major constituent of numerous cellular compounds, including proteins, amino acids, nucleic acids and lipids. While N deprivation is known to have severe consequences for primary carbon metabolism, the effect on chloroplast lipid metabolism has not been analysed in higher plants. Nitrogen limitation in Arabidopsis led to a decrease in the chloroplast galactolipid monogalactosyldiacylglycerol (MGDG) and a concomitant increase in digalactosyldiacylglycerol (DGDG), which correlated with an elevated expression of the DGDG synthase genes DGD1 and DGD2. The amounts of triacylglycerol and free fatty acids increased during N deprivation. Furthermore, phytyl esters accumulated containing medium-chain fatty acids (12:0, 14:0) and a large amount of hexadecatrienoic acid (16:3). Fatty acid phytyl esters were localized to chloroplasts, in particular to thylakoids and plastoglobules. Different polyunsaturated acyl groups were found in phytyl esters accumulating in Arabidopsis lipid mutants and in other plants, including 16:3 and 18:3 species. Therefore N deficiency in higher plants results in a co-ordinated breakdown of galactolipids and chlorophyll with deposition of specific fatty acid phytyl esters in thylakoids and plastoglobules of chloroplasts.     

猪PID1基因CDS区的克隆及其mRNA表达与肌内脂肪沉积关系

为了探索PID1(Phosphotyrosine interaction domain containing1)基因的表达与脂肪沉积的关系,文章利用兼并引物进行RT-PCR从猪脂肪和肌肉组织中克隆PID1基因CDS(Coding region)区全序列,并采用荧光定量PCR方法对大白猪、鲁莱黑猪、莱芜猪3个猪品种的肝脏、脂肪和肌肉组织PID1基因mRNA表达进行了相对定量分析。结果表明:经克隆、测序,得到了猪PID1基因654bp全编码区序列,通过Blast比对,与人、大鼠、牛有93.88%、66.94%、88.07%的同源性。PID1基因在同一个品种猪中mRNA表达水平总体表现为:肝脏脂肪肌肉。在不同品种3种组织中PID1基因mRNA表达水平总体表现为:莱芜猪鲁莱黑猪大白猪,其中肝脏中差异显著(P0.05),但是在脂肪和肌肉组织中莱芜猪与鲁莱黑猪差异不显著(P0.05)。对于高肌内脂肪(LWH)、中等肌内脂肪(LWI)和低肌内脂肪(LWL)沉积的3组莱芜猪,PID1基因在肝脏组织中的表达水平是LWH显著高于LWL(P0.05),在肌肉组织中则是LWH显著高于LWI和LWL(P0.05)。PID1基因在莱芜猪品种内3个组织中mRNA表达量与IMF含量相关均不显著,而在品种间3个组织中mRNA表达量与IMF含量呈显著正相关(P0.05)。结果提示:PID1的表达可能与脂肪沉积性状存在一定的关系。     

Investigation of porcine FABP3 and LEPR gene polymorphisms and mRNA expression for variation in intramuscular fat content

Porcine chromosome 6 (SSC6) has been reported to have QTL affecting intramuscular fat content (IMF) in multiple populations. The objective of this study was to investigate the effect of FABP3 and LEPR genetic variations as well as their mRNA expression on the IMF trait in a three-generation of Korean native pig and Yorkshire crossed animals. Several polymorphisms of the FABP3 (HinfI, HaeIII and HinfI*) were significantly associated with moisture, tenderness and flavor score (P < 0.05), and were used to construct haploytpes: haplotype 1 (-TCT-) increased the marbling and intramuscular fat content, however, haplotype 2 (-CCT-) decreased tenderness. The LEPR AvaII polymorphism showed significant association with moisture, intramuscular fat, cholesterol and flavor score (P < 0.05). The linkage analyses with six microsatellites mapped FABP3 gene in the interval between the markers Sw1129 and S0228 (Sw1129—11.7 cM—FABP3—9.1 cM—S0228), and the LEPR gene between the markers S0121 and Sw322 (S0121—7.5 cM—LEPR—28.5 cM—Sw322). QTL mapping suggested a significant QTL affecting Moisture (83 cM) and IMF (84 cM) located close to marker S0228. The gene expression results showed that in the loin muscle, both of the FABP3 and LEPR genes showed significantly higher expression in pigs with higher IMF%, however, in the backfat, only FABP3 showed differential expression between these two groups of pigs (significantly higher expression in pigs with lower IMF%) (P < 0.05). In the liver, both of these two genes did not show any difference between the high and low IMF% groups.     

Seasonal variations in fatty acid composition of pasture forage plants and CLA content in ewe milk fat

The relations between fatty acids (FAs) composition of pasture forage plants and the content of conjugated linoleic acid (CLA) as a total content of cis-9, trans-11 + trans-7, cis-9 + trans-8, cis-10 CLA isomers in ewes’ milk fat during natural pasture season (April–September) were investigated. The extracts of ewes’ milk fat samples as well as the pasture samples were analyzed for fatty acid composition by capillary gas chromatography with flame ionization and mass spectrometric detection. α-Linolenic, linoleic, and palmitic acids were predominant in pasture plants, and their contents varied during pasture season. The most abundant and most varied fatty acid compound in pasture plants was α-linolenic acid. Its content significantly decreased from 62% to 39% (of total FA) (P < 0.001) from May to August, and subsequently it slightly (57%) increased from August to September (P < 0.05), compared with the beginning of pasture season. Similarly, the content of CLA in ewes’ milk fat decreased from 2.4% in May to 1.3% in August (P < 0.001), and subsequently it rose to 2.6% in September (P < 0.001). The α-linolenic/linoleic acid ratio in the pasture sample decreased from 4.36 in May to 1.97 in August (P < 0.001), and subsequently it increased to 3.14 in September (P < 0.001); thus, it reached the level approaching to that at the beginning of pasture season. The pasture seasonal variations in the ratio were directly proportional to the corresponding content of CLA and indirectly proportional to the ratio in ewes’ milk fat. The results suggest that the seasonal variations in CLA content in ewes’ milk fat are related primarily to the seasonal variation in α-linolenic acid content in grass lipids.     

The effect of oxytetracycline on the fat content and fatty acid composition of the egg yolk

The effects of oxytetracycline (OXT) at doses of 0.291, 0.461, 0.922, 1.383 and 1.844 g/l in drinking water on the egg quality and on the fat content and fatty acid composition of egg yolk were studied. OXT had no effect on egg weight, yolk weight or shell thickness. Increasing availability of OXT in water reduced cholesterol and triglyceride in the egg yolk while it had no effect on the phospholipid content. OXT at higher doses favoured unsaturated and polyunsaturated fatty acids relative to saturated fatty acids in the yolk.     

Training affects muscle phospholipid fatty acid composition in humans.

Training improves insulin sensitivity, which in turn may affect performance by modulation of fuel availability. Insulin action, in turn, has been linked to specific patterns of muscle structural lipids in skeletal muscle. This study investigated whether regular exercise training exerts an effect on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P < 0.05). The ratio between n-6 and n-3 fatty acids was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P < 0.05). In contrast, training did not affect muscle triacylglycerol fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P < 0.05). In this model, diet plays a minimal role, as the influence of dietary intake is similar on both legs. Regular exercise training per se influences the phospholipid fatty acid composition of muscle membranes but has no effect on the composition of fatty acids stored in triacylglycerols within the muscle.     

Tissue-specific fatty acid composition,cellularity, and gene expression in diverse cattle breeds

The nutritional quality of beef relates to the fatty acid (FA) composition of bovine adipose tissue. Those molecular mechanisms that induce the differing amounts and composition of fat in cattle breeds according to age at maturity and purpose of production remain unclear. Therefore, this study investigated the composition of total FAs, adipocyte size, and expression of some key genes involved in several adipogenesis and lipogenesis pathways measured in distinct adipose tissue depots from bulls of the genetically diverse cattle breeds Aberdeen Angus (n = 9), Gascon (n = 10), Holstein (n = 9), and Fleckvieh (n = 10). The animals were finished under identical housing and feeding conditions until slaughter at a similar age of 17 months. After slaughter, cod adipose tissue (CAT), subcutaneous adipose tissue (SAT), and M. longissimus lumborum (MLL) samples were collected. The saturated FA proportions were higher (P < .01) in CAT than in SAT across all breeds, whereas monounsaturated FA proportions were consistently higher (P < .001) in SAT compared to CAT and MLL. Aberdeen Angus bulls were distinguished from the other breeds in the proportions of mostly de novo synthesized C14:0, C16:0, C14:1n-5, C16:1n-7, and conjugated linoleic acid (P < .05). Adipocyte size decreased in the order CAT > SAT > MLL, and the largest adipocytes were observed in CAT of Holstein bulls (P < .05). Gene expression differences were more pronounced between adipose tissue depots than between breeds. The expression levels of ACACA, FASN, and SCD1 genes were related to tissue-specific, and to a lesser extent also breed-specific, differences in FA composition.     

Integrating genome-wide association study with RNA-seq revealed DBI as a good candidate gene for intramuscular fat content in Beijing black pigs

Increasing intramuscular fat (IMF) content can enhance the sensory quality of meat, including tenderness, juiciness, flavor, and color. Genome-wide association study and RNA-sequencing (RNA-seq) analysis were used to identify candidate IMF genes in Beijing Black pigs, a popular species among consumers in northern China. Two and three single nucleotide polymorphisms were significantly associated with IMF in SSC13 and SSC15 respectively. Solute carrier family 4 member 7 (SLC4A7) on SSC13 and insulin induced gene 2 (INSIG2), coiled-coil domain containing 93 (CCDC93), and diazepam binding inhibitor acyl-CoA binding protein (DBI) on SSC15 are good candidate genes in this population. Furthermore, RNA-seq analysis was performed between high and low IMF groups, and 534 differentially expressed genes were identified. In addition, based on differentially expressed genes, Kyoto Encyclopedia of Genes and Genomes analysis revealed that peroxisome proliferator-activated receptors and FoxO signaling pathway pathways might contribute to IMF. Moreover, the DBI gene was identified as a candidate for IMF both by genome-wide association study and RNA-seq analysis, suggesting that it might be a crucial candidate gene for influencing IMF in Beijing Black pigs.