Lipid Deposition and Metabolism in Local and Modern Pig Breeds: A Review

Meat Characteristics, Expression of Myosin Heavy Chain and Metabolism-Related Genes in Thai Native Pigs

This study investigated the meat quality, expression of myosin heavy chain (MyHC) and metabolism-related genes, ribonucleotides and fatty acids in Longissimus thoracis of Thai native pigs (TNPs) from different geographical regions (GR). Forty-one 9-10-month-old castrated TNPs (BW 60 kg), consisting of 18, 11 and 12 pigs from Northern (NT), Southern (ST) and Northeastern (NE) regions, respectively, were slaughtered. GR did not affect (p > 0.05) the expression of MyHC, phosphoglycerate mutase 1, cytosolic glycerol-3-phosphate dehydrogenase, triosephosphate isomerase 1 and adipocyte fatty acid binding protein genes. The trend of MyHC was MyHC IIx > MyHC IIb > MyHC IIa > MyHC I. The NT loin had higher (p < 0.05) glycogen, C18:2n6, C20:4n6 and cooking loss, lower inosine, inosine monophosphate and hypoxanthine and a shorter sarcomere length than the ST and NE loins. The ST loin had a lower (p < 0.05) a* compared to other loins. Principal component analysis established significant relationships between the TNP and specific meat quality traits. This finding suggests that GR affected the meat quality, ribonucleotides and selected fatty acids in TNPs. These results provide relevant information that can be used to optimize the use of Thai native pork.

- Invited Review - Current status, challenges and prospects for pig production in Asia

Asia is not only the primary region for global pig production but also the largest consumer of pork worldwide. Although the pig production in Asia has made great progress in the past, it still is confronted with numerous challenges. These challenges include: inadequate land and feed resources, a substantial number of small-scale pig farms, escalating pressure to ensure environmental conservation, control of devastating infectious diseases, as well as coping with high temperatures and high humidity. To solve these problems, important investments of human and financial capital are required to promote large-scale production systems, exploit alternative feed resources, implement precision feeding, and focus on preventive medicine and vaccines as alternatives to antibiotics, improve pig breeding, and increase manure recycling. Implementation of these techniques and management practices will facilitate development of more environmentally-friendly and economically sustainable pig production systems in Asia, ultimately providing consumers with healthy pork products around the world.

Effects of Genotype on Pig Carcass, Meat Quality and Consumer Sensory Evaluation of Loins and Bellies

The objective of the study was to compare carcass and meat quality among Lithuanian White, Lithuanian Indigenous Wattle and conventional hybrids as well as consumer sensory evaluations. The pigs were slaughtered at a live weight of approximately 95-100 kg. After 24 h of slaughter, carcasses were evaluated and sampled for the analysis of meat quality traits of loins and consumer evaluation of cooked loins and baked bellies. The pigs of both Lithuanian breeds had higher backfat thickness and depth of underbelly but lower loin area compared with hybrids. However, more fatty local breeds had higher intramuscular fat content but lower cholesterol content than hybrids. The loins from local pigs displayed higher pH and colour with lower lightness and yellowness but higher redness and also lower cooking loss, shear force and hardness than conventional hybrids. Pork from lean hybrids had a higher proportion of polyunsaturated fatty acids and more favourable lipid quality indices such as atherogenic (AI) and thrombogenic (TI) indices and the hypocholesterolemic/hypercholesterolemic (h/H) ratio; however, the peroxidisability index (PI) and iodine value (IV) were less favourable compared with local pigs. Consumers evaluated cooked loins and baked bellies. The loins from local breeds scored higher in juiciness, taste and overall acceptability compared with conventional hybrids. However, a higher overall acceptability was observed for the lean bellies of hybrids. The results can be used to increase pork consumption choices.

Transcriptome and Metabolome Analyses Provide Insight into the Glucose-Induced Adipogenesis in Porcine Adipocytes

Glucose is a major energy substrate for porcine adipocytes and also serves as a regulatory signal for adipogenesis and lipid metabolism. In this study, we combined transcriptome and metabolome analyses to reveal the underlying regulatory mechanisms of high glucose (HG) on adipogenesis by comparing differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) identified in porcine adipocytes. Results showed that HG (20 mmol/L) significantly increased fat accumulation in porcine adipocytes compared to low glucose (LG, 5 mmol/L). A total of 843 DEGs and 365 DAMs were identified. Functional enrichment analyses of DEGs found that multiple pathways were related to adipogenesis, lipid metabolism, and immune-inflammatory responses. PPARγ, C/EBPα, ChREBP, and FOS were identified as the key hub genes through module 3 analysis, and PPARγ acted as a central regulator by linking genes involved in lipid metabolism and immune-inflammatory responses. Gene-metabolite networks found that PPARγ-13-HODE was the most important interaction relationship. These results revealed that PPARγ could mediate the cross-talk between adipogenesis and the immune-inflammatory response during adipocyte maturation. This work provides a comprehensive view of the regulatory mechanisms of glucose on adipogenesis in porcine adipocytes.

Comprehensive Atlas of Alternative Splicing Reveals NSRP1 Promoting Adipogenesis through CCDC18

Alternative splicing (AS) plays a crucial role in regulating gene expression, function, and diversity. However, limited reports exist on the identification and comparison of AS in Eastern and Western pigs. Here, we analyzed 243 transcriptome data from eight tissues, integrating information on transcription factors (TFs), selection signals, splicing factors (SFs), and quantitative trait loci (QTL) to comprehensively study alternative splicing events (ASEs) in pigs. Five ASE types were identified, with Mutually Exclusive Exon (MXE) and Skipped Exon (SE) ASEs being the most prevalent. A significant portion of genes with ASEs (ASGs) showed conservation across all eight tissues (63.21-76.13% per tissue). Differentially alternative splicing genes (DASGs) and differentially expressed genes (DEGs) exhibited tissue specificity, with blood and adipose tissues having more DASGs. Functional enrichment analysis revealed coDASG_DEGs in adipose were enriched in pathways associated with adipose deposition and immune inflammation, while coDASG_DEGs in blood were enriched in pathways related to immune inflammation and metabolism. Adipose deposition in Eastern pigs might be linked to the down-regulation of immune-inflammation-related pathways and reduced insulin resistance. The TFs, selection signals, and SFs appeared to regulate ASEs. Notably, ARID4A (TF), NSRP1 (SF), ANKRD12, IFT74, KIAA2026, CCDC18, NEXN, PPIG, and ROCK1 genes in adipose tissue showed potential regulatory effects on adipose-deposition traits. NSRP1 could promote adipogenesis by regulating alternative splicing and expression of CCDC18. Conducting an in-depth investigation into AS, this study has successfully identified key marker genes essential for pig genetic breeding and the enhancement of meat quality, which will play important roles in promoting the diversity of pork quality and meeting market demand.

Persistence of autozygosity in crossbreds between autochthonous and cosmopolitan breeds of swine: a simulation study

Crossbreeding might be a valid strategy to valorize local pig breeds. Crossbreeding should reduce homozygosity and, as a consequence, yield hybrid vigor for fitness and production traits. This study aimed to quantify the persistence of autozygosity in terminal crossbred pigs compared with purebreds and, in turn, identify genomic regions where autozygosity's persistence would not be found. The study was based on genotyping data from 20 European local pig breeds and three cosmopolitan pig breeds used to simulate crossbred offspring. This study consisted of two steps. First, one hundred matings were simulated for each pairwise combination of the 23 considered breeds (for a total of 276 combinations), ignoring the sex of the parent individuals in order to generate purebred and crossbred matings leveraging all the germplasm available. Second, a few preselected terminal-maternal breed pairs were used to mimic a realistic terminal crossbreeding system: (i) Mora Romagnola (boars) or Cinta Senese (boars) crossed with Large White (sows) or Landrace (sows); (ii) Duroc (boars) crossed with Mora Romagnola (sows) or Cinta Senese (sows). Runs of homozygosity was used to estimate genome-wide autozygosity (FROH). Observed FROH was higher in purebreds than in crossbreds, although some crossbred combinations showed higher FROH than other purebred combinations. Among the purebreds, the highest FROH values were observed in Mora Romagnola and Turopolje (0.50 and 0.46, respectively). FROH ranged from 0.04 to 0.16 in the crossbreds Alentejana × Large White and Alentejana × Iberian, respectively. Persistence of autozygosity was found in several genomic segments harboring regions where quantitative trait loci (QTLs) were found in the literature. The regions were enriched in QTLs involved in fatty acid metabolism and associated with performance traits. This simulation shows that autozygosity persists in most breed combinations of terminal crosses. Results suggest that a strategy for crossbreeding is implemented when leveraging autochthonous and cosmopolitan breeds to obtain most of the hybrid vigor.

Comparison of Growth Performance, Carcass Properties, Fatty Acid Profile, and Genes Involved in Fat Metabolism in Nanyang and Landrace Pigs

This study compared the growth, carcass properties, fatty acid profile, lipid-producing enzyme activity, and expression pattern of genes involved in fat metabolism in Nanyang and Landrace pigs. In the study, 32 Nanyang (22.16 ± 0.59 kg) and 32 Landrace barrows (21.37 ± 0.57 kg) were selected and divided into two groups, each with eight pens and four pigs per pen. The trial period lasted 90 days. The findings showed that the Nanyang pigs had lower average daily weight gain and lean percentage and higher average backfat thickness and lipogenic enzyme activities, including for acetyl-CoA carboxylase, glucose-6-phosphate dehydrogenase, malic enzyme, and fatty acid synthase, than the Landrace pigs. A total of 14 long-chain fatty acids were detected using HPLC-MS, in which it was found that the levels of C14:0, C18:1n-9, C20:1n-9, C20:4n-6, and MUFA were up-regulated and C18:2n-6, C18:3n-3, PUFA n6, n3/n6, and total PUFA were down-regulated in the Nanyang pigs. Moreover, the mRNA levels for genes involved in fat metabolism, ME1, FAS, and LPL, were higher and the expression of SREBP1 mRNA was lower in the Nanyang pigs. Our results suggest genetic differences between the pig breeds in terms of growth, carcass traits, lipogenic enzyme activities, fatty acid profile, and the mRNA expression of genes involved in fat metabolism in subcutaneous fat tissue, which may provide a basis for high-quality pork production. Further studies are needed to investigate the regulation of lipid metabolism.

Effects of Animal Diet and Processing Methods on the Quality Traits of Dry-Cured Ham Produced from Turopolje Pigs

The Turopolje pig (TP) is a local Croatian pig breed that almost became extinct in the second half of the 20th century. Today, the TP is still endangered, and a new conservation strategy based on products with higher added value is needed to preserve the breed. There is little information on the quality of TP meat products such as smoked and dry-cured ham, including the impact of natural feeds or processing innovations such as smoke reduction. This study, therefore, investigated the effects of the animal's diet (either conventionally fed or acorn-supplemented) and the processing method (standard or lightly smoked) on the quality traits of dry-cured TP ham. Twenty hams, evenly distributed among the treatments, were processed for 15 months and then analysed for physicochemical and textural traits, volatiles and sensory profile. The hams from acorn-supplemented pigs lost less weight during processing (p ≤ 0.05). Otherwise, the diet had no significant effect on most examined ham traits. The exceptions were protein content and the texture parameter hardness, which decreased (p ≤ 0.05), and the degree of proteolysis and colour parameters, which increased (p ≤ 0.05) as a result of acorn supplementation. However, these effects were generally small and varied between the inner (m. biceps femoris) and outer (m. semimembranosus) muscles. Furthermore, acorn supplementation was associated with less typical ham odour and lower sensory scores for sweetness and colour uniformity (p ≤ 0.05). The smoke reduction had no effect on the physicochemical and colour properties but resulted in a significant reduction (p ≤ 0.05) in the volatile phenolic compounds and an improved texture to the hams. This was reflected both in reduced (p ≤ 0.05) hardness, identified in the instrumental analysis, and in an increased (p ≤ 0.05) softness, solubility and moistness, identified in the sensory evaluation. To summarize, the quality of the TP ham under the conditions studied was only slightly affected by acorn supplementation, whereas reduced smoking had a more significant effect, which was mainly reflected in an improved texture.

Genomic architecture of carcass and pork traits and their association with immune capacity

Carcass and pork traits have traditionally been considered of prime importance in pig breeding programmes. However, the changing conditions in modern farming, coupled with antimicrobial resistance issues, are raising the importance of health and robustness-related traits. Here, we explore the genetic architecture of carcass and pork traits and their relationship with immunity phenotypes in a commercial Duroc pig population. A total of nine traits related to fatness, lean content and meat pH were measured at slaughter (∼190 d of age) in 378 pigs previously phenotyped (∼70 d of age) for 36 immunity-related traits, including plasma concentrations of immunoglobulins, acute-phase proteins, leukocytes subpopulations and phagocytosis. Our study showed medium to high heritabilities and strong genetic correlations between fatness, lean content and meat pH at 24 h postmortem. Genetic correlations were found between carcass and pork traits and white blood cells. pH showed strong positive genetic correlations with leukocytes and eosinophils, and strong negative genetic correlations with haemoglobin, haematocrit and cytotoxic T cell proportion. In addition, genome-wide association studies (GWASs) pointed out four significantly associated genomic regions for lean meat percentages in different muscles, ham fat, backfat thickness, and semimembranosus pH at 24 h. The functional annotation of genes located in these regions reported a total of 14 candidate genes, with BGN, DPP10, LEPR, LEPROT, PDE4B and SLC6A8 being the strongest candidates. After performing an expression GWAS for the expression of these genes in muscle, two signals were detected in cis for the BGN and SLC6A8 genes. Our results indicate a genetic relationship between carcass fatness, lean content and meat pH with a variety of immunity-related traits that should be considered to improve immunocompetence without impairing production traits.

A meta-analysis of genetic and phenotypic diversity of European local pig breeds reveals genomic regions associated with breed differentiation for production traits

BACKGROUND

Intense selection of modern pig breeds has resulted in genetic improvement of production traits while the performance of local pig breeds has remained lower. As local pig breeds have been bred in extensive systems, they have adapted to specific environmental conditions, resulting in a rich genotypic and phenotypic diversity. This study is based on European local pig breeds that have been genetically characterized using DNA-pool sequencing data and phenotypically characterized using breed level phenotypes related to stature, fatness, growth, and reproductive performance traits. These data were analyzed using a dedicated approach to detect signatures of selection linked to phenotypic traits in order to uncover potential candidate genes that may underlie adaptation to specific environments.

RESULTS

Analysis of the genetic data of European pig breeds revealed four main axes of genetic variation represented by the Iberian and three modern breeds (i.e. Large White, Landrace, and Duroc). In addition, breeds clustered according to their geographical origin, for example French Gascon and Basque breeds, Italian Apulo Calabrese and Casertana breeds, Spanish Iberian, and Portuguese Alentejano breeds. Principal component analysis of the phenotypic data distinguished the larger and leaner breeds with better growth potential and reproductive performance from the smaller and fatter breeds with low growth and reproductive efficiency. Linking the signatures of selection with phenotype identified 16 significant genomic regions associated with stature, 24 with fatness, 2 with growth, and 192 with reproduction. Among them, several regions contained candidate genes with possible biological effects on stature, fatness, growth, and reproductive performance traits. For example, strong associations were found for stature in two regions containing, respectively, the ANXA4 and ANTXR1 genes, for fatness in a region containing the DNMT3A and POMC genes and for reproductive performance in a region containing the HSD17B7 gene.

CONCLUSIONS

In this study on European local pig breeds, we used a dedicated approach for detecting signatures of selection that were supported by phenotypic data at the breed level to identify potential candidate genes that may have adapted to different living environments and production systems.

Effects of Supplementing Growing-Finishing Crossbred Pigs with Glycerin, Vitamin C and Niacinamide on Carcass Characteristics and Meat Quality

The objective of this study was to determine the influence of supplementing the diet of growing-finishing pigs with glycerin and/or a mixture of vitamin C and niacinamide on carcass traits and pork quality. Eighty-four weaned piglets with an initial average body weight of 20.35 ± 2.14 kg were assigned, at random, to four groups for a 103-day feeding experiment: control; glycerin-supplemented group; vitamin C and niacinamide-supplemented group; and glycerin, vitamin C and niacinamide-supplemented group. At the end of the experiment, three pigs/group were randomly selected and slaughtered, and samples were collected for analysis. The results indicated that supplementing crossbred pigs with glycerin, vitamin C and niacinamide simultaneously increased the redness (a*) value (p < 0.05), glycerol content (p < 0.01) and myristoleic acid content (p < 0.01) in the longissimus dorsi and tended to increase the level of flavor amino acids, linoleic acid, linolenic acid and erucic acid, as well as the percentage and density of type I myofibers in the longissimus dorsi and the semimembranosus muscle. Glycerin had an influence (p < 0.01) on the erucic acid content in the longissimus dorsi and the semimembranosus muscle, and vitamin C and niacinamide had an interaction effect (p < 0.05) on the redness (a*) value of the longissimus dorsi. Glycerin, vitamin C and niacinamide supplementation in the diet of crossbred pigs improved the color, flavor and nutritional value of pork, which contributed to an increased intent to purchase this product.

Effects of lysine concentration of the diet on growth performance and meat quality in finishing pigs with high slaughter weights

The present study aimed to investigate the feasibility of using a diet low in lysine content as a means for increasing the intramuscular fat (IMF) content and pork muscle quality of finishing pigs. Thirty-two crossbred gilts and barrows weighing approximately 80 kg were fed either a low-lysine diet (0.60%; Low-lys) or a control diet (0.80% lysine; Med-lys) under a 2 × 2 factorial arrangement of treatments. The animals were slaughtered at a 132-kg body weight (BW) on average, followed by physicochemical analyses and sensory evaluation on Longissimus lumborum (LL) and Semitendinosus (ST) muscles. The average daily gain (ADG) did not differ between the Med-lys and Low-lys groups. However, ADG exhibited a tendency of sex × diet interaction (p = 0.09), being greater for barrows vs. gilts on the Low-lys diet (p < 0.05), but not on the Med-lys diet. Backfat thickness adjusted for 132-kg BW also exhibited the interaction; it was greater for the Low-lys vs. Med-lys group within gilts but tended to be less for the former in barrows (p = 0.08). The IMF content was not influenced by the diet or sex in either LL or ST. The a*, b*, and Warner-Bratzler Shear Force values and fatty acid composition were influenced by the sex or diet in either or both of the muscles, but the treatment effects did not apparently influence the meat quality. Sensory scores for the flavor, juiciness, tenderness, umami, and palatability of cooked muscle were not influenced by the diet in either LL or ST. When the LL and ST data were pooled, scores for those sensory attributes were positively correlated with the IMF content, which was associated with overall greater IMF contents and greater sensory scores for ST vs. LL. Collectively, the Low-lysine diet seemingly elicited the intended lysine deficiency in gilts as indicated by the increased BFT due to the diet. However, the Low-lys diet was not effective for increasing the IMF deposition or eating quality of the pork muscle of finishing pigs slaughtered at high BW probably because its lysine content was not low enough to elicit either outcome.

Integrative Analysis of Transcriptomic and Lipidomic Profiles Reveals a Differential Subcutaneous Adipose Tissue Mechanism among Ningxiang Pig and Berkshires, and Their Offspring

Adipose tissue composition contributes greatly to the quality and nutritional value of meat. Transcriptomic and lipidomic techniques were used to investigate the molecular mechanisms of the differences in fat deposition in Ningxiang pigs, Berkshires and F1 offspring. Transcriptomic analysis identified 680, 592, and 380 DEGs in comparisons of Ningxiang pigs vs. Berkshires, Berkshires vs. F1 offspring, and Ningxiang pigs vs. F1 offspring. The lipidomic analysis screened 423, 252, and 50 SCLs in comparisons of Ningxiang pigs vs. Berkshires, Berkshires vs. F1 offspring, and Ningxiang pigs vs. F1 offspring. Lycine, serine, and the threonine metabolism pathway, fatty acid biosynthesis and metabolism-related pathways were significantly enriched in comparisons of Berkshires vs. Ningxiang pigs and Berkshires vs. F1 offspring. The DEGs (PHGDH, LOC110256000) and the SCLs (phosphatidylserines) may have a great impact on the glycine, serine, and the threonine metabolism pathway. Moreover, the DEGs (FASN, ACACA, CBR4, SCD, ELOV6, HACD2, CYP3A46, CYP2B22, GPX1, and GPX3) and the SCLs (palmitoleic acid, linoleic acid, arachidonic acid, and icosadienoic acid) play important roles in the fatty acid biosynthesis and metabolism of fatty acids. Thus, the difference in fat deposition among Ningxiang pig, Berkshires, and F1 offspring may be caused by differences in the expression patterns of key genes in multiple enriched KEGG pathways. This research revealed multiple lipids that are potentially available biological indicators and screened key genes that are potential targets for molecular design breeding. The research also explored the molecular mechanisms of the difference in fat deposition among Ningxiang pig, Berkshires, and F1 pigs, and provided an insight into selection for backfat thickness and the fat composition of adipose tissue for future breeding strategies.

Comparison between Berkshire and crossbreed on meat quality, and investigation of the relationship with fatty acid composition and meat quality

This study aimed to compare meat quality traits between Berkshire and crossbreed (Landrace × Yorkshire × Duroc), and to investigate the relationship between meat quality traits and fatty acid composition. 20 Berkshire and 20 crossbreed pigs were used to compare pork loin quality and to determine the relationship between measured variables. 23 variables were measured including proximate composition, pH, drip loss and cooking loss, Warner-Bratzler shear force, and fatty acid composition. Berkshire had higher moisture content, pH, water-holding capacity, saturated fatty acids, and redness than the crossbreed pig (p < 0.05). The fat content and polyunsaturated fatty acid were low (p < 0.05) in Berkshire. Correlation analysis showed a negatively correlation between moisture and fat content, and a positively correlation between saturated fatty acid and fat content. Moreover, saturated fatty acid and polyunsaturated fatty acid were negatively correlated. As a result of factor analysis and partial least square regression, saturated fatty acid and polyunsaturated fatty acid were estimated to be the main factors affecting quality characteristics of pork. Pig breed is associated with differences in meat quality, and fatty acid composition can have an effect on meat quality parameters.

Postmortem Metabolism and Pork Quality Development Are Affected by Electrical Stimulation across Three Genetic Lines

Variations in postmortem metabolism in muscle impact pork quality development. Curiously, some genetic lines are more refractile to adverse pork quality development than others and may regulate energy metabolism differently. The aim of this study was to challenge pork carcasses from different genetic populations with electrical stimulation (ES) to determine how postmortem metabolism varies with genetic line and explore control points that reside in glycolysis in dying muscle. Three genetic populations (GP) were subjected to ES (100 V or 200 V, 13 pulses, 2 s on/2 s off) at 15- or 25-min post-exsanguination, or no stimulation (NS). Genetic population affected relative muscle relative abundance of different myosin heavy chains, glycogen, G6P, and lactate concentrations. Genetic lines responded similarly to ES, but a comparison of ES treatment groups revealed a trend for an interaction between voltage, time of ES, and time postmortem. Higher voltage accelerated pH decline at 20 min up to 60 min postmortem. Trends in color and firmness scores and L* values were consistent with pH and metabolite data. These data show that genetic populations respond differently to postmortem perturbation by altering glycolytic flux and suggest differences in postmortem glycolysis may be partially responsible for differences in meat quality between genetic populations, though not entirely.

Transcriptome changes during osteogenesis of porcine mesenchymal stem cells derived from different types of synovial membranes and genetic background

Synovial membrane mesenchymal stem cells (SMSCs) often serve as in vitro model for bone disease, but the molecular mechanisms driving osteogenesis in SMSCs from different donor cells of various sources and breeds remain unclear. In this study, porcine SMSCs isolated from adipose synovium (FP) and fibrous synovium (FS) of Angeln Saddleback (AS) and German Landrace (DL) were used to discover the signaling network change after osteogenic induction. During osteogenic differentiation, mineral deposition was first observed at day 14 and further increased until day 21. Transcriptional changes between day 1 and day 21 were enriched in several signaling pathways, including Wnt, PI3K-Akt, and TGF-beta pathway. Certain pathways related to osteogenesis, including osteoblast differentiation, regulation of bone mineralization, and BMP signaling pathway, were enriched at late time points, as confirmed by the osteogenic markers ALPL, COL1A1, and NANOG. A fraction of differentially expressed genes (DEGs) were found between FP and FS, while DEGs between AS and DL increased during the differentiation phase until day 7 and then decreased from day 14 to day 21. These genes are involved in several important signaling pathways, including TGF-beta, Wnt, and lipid-related signaling pathways, suggesting that SMSCs from these two breeds have different osteogenic capabilities.

A Comparative Study on the Carcass and Meat Chemical Composition, and Lipid-Metabolism-Related Gene Expression in Korean Hanwoo and Brindle Chikso Cattle

The objective of this study was to elucidate the effect of cattle breed on carcass and meat chemical composition, fatty acid profiles, and lipid-metabolism-related genes. For this study, same-age Hanwoo and Chikso steers (n = 6 per breed) reared under identical conditions were used. Immediately after slaughter, muscle tissues were collected for analysis of mRNA expression. At 24 h post-mortem, the carcasses were assessed for carcass traits (marbling score, meat yield, etc.), and meat quality and fatty acid profiles in the longissimus lumborum (LL) and semimembranosus (SM) muscles. The results showed that no differences in the slaughter weight, dressing rate, back-fat thickness, trimmed fat, and total meat yield occurred between the two breeds (p > 0.05). However, Hanwoo cattle had a higher marbling score, intramuscular fat (IMF) content, and expression level of lipid-metabolism-related genes such as lipoprotein lipase, peroxisome proliferator-activated receptor gamma, and fatty acid binding protein 4, compared with Chikso (p < 0.05). Contrastingly, Chikso had a higher total unsaturated fatty acid content and expression level of stearoyl CoA desaturase 1 (p < 0.05). It may be said that the difference in the expression levels of lipid-metabolism-related genes could be the molecular factors underlying IMF deposition and fatty acid profile differences in the beef from the two breeds.

Transcriptome, proteome and metabolome analysis provide insights on fat deposition and meat quality in pig

Intramuscular fat (IMF) content, which is an important determinant of meat quality characteristics such as tenderness, juiciness and flavor, has long been a research hotspot. Chinese local pig breeds are famous for their excellent meat quality which is mainly reflected in the high IMF content, strong hydraulic system and et al. However, there are few analysis of meat quality by omics methods. In our study, we identified 12 different fatty acids, 6 different amino acids, 1,262 differentially expression genes (DEGs), 140 differentially abundant proteins (DAPs) and 169 differentially accumulated metabolites (DAMs) (p < 0.05) with metabolome, transcriptome, and proteome. It has been found that DEGs, DAPs and DAMs were enriched in the Wnt signaling pathway, PI3K-Akt signaling pathway, Rap1 signaling pathway, and Ras signaling pathway which were related to meat quality. Moreover, our Weighted genes co-expression network construction (WGCNA) showed RapGEF1 was the key gene related to IMF content and the RT-qPCR analysis was used to perform validation of the significant genes. In summary, our study provided both fundamental data and new insights to further uncover the secret of pig IMF content.

Differences in Muscle Lipogenic Gene Expression, Carcass Traits and Fat Deposition among Three Iberian Pig Strains Finished in Two Different Feeding Systems

The Iberian pig breed includes several well-differentiated strains. The present study evaluated carcass traits, fat deposition and muscle expression of important lipogenic genes (SCD, ME1, ACACA, FASN, EGR1, ACOX and ACLY) using 65 male pigs of 3 Iberian strains (20 Lampiño, 23 Torbiscal, and 22 Retinto) finished either in a conventional, concentrate-based system (CF) or in montanera (MF), a traditional free-range system with acorn feeding. Torbiscal had the highest ham, Longissimus thoracis and prime cuts yields, and the thinnest subcutaneous adipose tissue (SAT). Retinto had the highest monounsaturated fatty acids (MUFA) and percentage of intramuscular fat (IMF), while Lampiño had the greatest content of saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA), atherogenic (AI) and thrombogenic (TI) indexes in SAT. Conventionally finished pigs had the highest ham, L. thoracis and prime cuts yields, and SFA. Montanera-finished animals had the highest PUFA and MUFA contents, and the lowest AI, TI and n6/n3 ratio in SAT. In relation to gene expression, Retinto had the greatest SCD, FASN and ACLY levels. Most studied genes were overexpressed in CF pigs. In conclusion, MF pigs had healthier fat than CF pigs, and Retinto had the healthiest fat and the greatest lipogenic trend in muscle, supported by IMF and lipogenic gene expression.

Pork Fat and Meat: A Balance between Consumer Expectations and Nutrient Composition of Four Pig Breeds

Food fat content is one of the most controversial factors from a consumer's point of view. Aim: (1) The trends in consumer attitudes towards pork and the fat and meat compositions in Duroc and Altai meat breeds and Livny and Mangalitsa meat and fat breeds were studied. (2) Methods: Netnographic studies were used to assess Russian consumer purchasing behavior. Protein, moisture, fat, backfat fatty acid content from pigs, longissimus muscles, and backfat from (A) Altai, (L) Livny, and (M) Russian Mangalitsa breeds were compared with those from (D) Russian Duroc. Raman spectroscopy and histology were applied to the backfat analysis. (3) Results: The attitude of Russian consumers to fatty pork is contradictory: consumers note its high fat content as a negative factor, but the presence of fat and intramuscular fat is welcomed because consumers positively associate them with better taste, tenderness, flavor, and juiciness. The fat of the 'lean' D pigs did not show a "healthy" fatty acid ratio, while the n-3 PUFA/n-6 PUFA ratio in the fat of the M pigs was the best, with significant amounts of short-chain fatty acids. The highest UFA content, particularly omega 3 and omega 6 PUFA, was found in the backfat of A pigs with a minimum SFA content. The backfat of L pigs was characterized by a larger size of the adipocytes; the highest monounsaturated and medium chain fatty acid contents and the lowest short-chain fatty acid content; the ratio of omega 3 to omega 6 was 0.07, and the atherogenicity index in L backfat was close to that of D, despite the fact that D pigs are a meat type, while L pigs are a meat and fat type. On the contrary, the thrombogenicity index in L backfat was even lower than the D one. (4) Conclusions: Pork from local breeds can be recommended for functional food production. The requirement to change the promotion strategy for local pork consumption from the position of dietary diversity and health is stated.

RNA-seq transcriptome profiling of pigs' liver in response to diet with different sources of fatty acids

Pigs (Sus scrofa) are an animal model for metabolic diseases in humans. Pork is an important source of fatty acids (FAs) in the human diet, as it is one of the most consumed meats worldwide. The effects of dietary inclusion of oils such as canola, fish, and soybean oils on pig gene expression are mostly unknown. Our objective was to evaluate FA composition, identify changes in gene expression in the liver of male pigs fed diets enriched with different FA profiles, and identify impacted metabolic pathways and gene networks to enlighten the biological mechanisms' variation. Large White male pigs were randomly allocated to one of three diets with 18 pigs in each; all diets comprised a base of corn and soybean meal to which either 3% of soybean oil (SOY), 3% canola oil (CO), or 3% fish oil (FO) was added for a 98-day trial during the growing and finishing phases. RNA sequencing was performed on the liver samples of each animal by Illumina technology for differential gene expression analyses, using the R package DESeq2. The diets modified the FA profile, mainly in relation to polyunsaturated and saturated FAs. Comparing SOY vs. FO, 143 differentially expressed genes (DEGs) were identified as being associated with metabolism, metabolic and neurodegenerative disease pathways, inflammatory processes, and immune response networks. Comparing CO vs. SOY, 148 DEGs were identified, with pathways related to FA oxidation, regulation of lipid metabolism, and metabolic and neurodegenerative diseases. Our results help explain the behavior of genes with differential expression in metabolic pathways resulting from feeding different types of oils in pig diets.

Comprehensive Analysis of the lncRNA-miRNA-mRNA Regulatory Network for Intramuscular Fat in Pigs

Intramuscular fat (IMF) is an essential trait closely related to meat quality. The IMF trait is a complex quantitative trait that is regulated by multiple genes. In order to better understand the process of IMF and explore the key factors affecting IMF deposition, we identified differentially expressed mRNA, miRNA, and lncRNA in the longissimus dorsi muscle (LD) between Songliao Black (SL) pigs and Landrace pigs. We obtained 606 differentially expressed genes (DEGs), 55 differentially expressed miRNAs (DEMs), and 30 differentially expressed lncRNAs (DELs) between the SL pig and Landrace pig. Enrichment results from GO and KEGG indicate that DEGs are involved in fatty acid metabolism and some pathways related to glycogen synthesis. We constructed an lncRNA-miRNA-mRNA interaction network with 18 DELs, 11 DEMs, and 42 DEGs. Finally, the research suggests that ARID5B, CPT1B, ACSL1, LPIN1, HSP90AA1, IRS1, IRS2, PIK3CA, PIK3CB, and PLIN2 may be the key genes affecting IMF deposition. The LncRNAs MSTRG.19948.1, MSTRG.13120.1, MSTRG.20210.1, and MSTRG.10023.1, and the miRNAs ssc-miRNA-429 and ssc-miRNA-7-1, may play a regulatory role in IMF deposition through their respective target genes. Our research provides a reference for further understanding the regulatory mechanism of IMF.

miR-34a Regulates Lipid Droplet Deposition in 3T3-L1 and C2C12 Cells by Targeting LEF1

Intramuscular fat (IMF) content plays a key role in improving the flavor and palatability of pork. The IMF content varies between species, breeds, and individuals of the same breed. Hence, it is necessary to elucidate the mechanisms of IMF deposition to improve pork quality. Herein, the IMF content in the longissimus dorsi muscles of 29 Laiwu pigs was detected and divided into two groups, the H group (IMF > 12%) and the L group (IMF < 5%). RNA sequencing analysis showed 24 differentially expressed (DE) miRNA, and GO and KEGG analysis demonstrated that the DE miRNAs were significantly enriched in lipid metabolic process, lipid storage, Wnt, mTOR, and PPAR signaling pathways. miR-34a was found to be increased in the H group and 3T3-L1-derived adipocytes, while Lef1 was decreased. Luciferase reporter assays demonstrated that Lef1 was a potential target of miR-34a. Mechanism analysis revealed that miR-34a could increase lipid droplet deposition in 3T3-L1 and C2C12 cells by dampening the suppressive function of Lef1 on the transcription of adipogenic markers (i.e., Pparg, Cebpa, Fabp4, and Plin1). Moreover, overexpression of miR-34a could enhance the lipid deposition in the co-culture system of 3T3-L1 and C2C12 cells as well as in C2C12 cells cultured with conditioned medium from the progress of adipocyte differentiation. Taken together, our study indicated that miR-34a was an important positive modulator in the regulation of fatty metabolism and fat deposition by inhibiting the suppressive function of Lef1. These results might provide insight for the exploration of potential strategies to promote intramuscular fat deposition in livestock.

Comparison of the meat quality and fatty acid profile of muscles in finishing Xiangcun Black pigs fed varied dietary energy levels

To study the effects of dietary energy level on the meat quality of different muscles in finishing pigs, 400 Xiangcun Black pigs (BW = 79.55 ± 4.77 kg) were randomly assigned to 5 treatments with varied calculated digestive energy (DE) at 3,050, 3,100, 3,150, 3,200 and 3,250 kcal/kg, respectively. Each treatment had 8 replicates with 10 pigs per replicate. Meat quality, amino acid and fatty acid composition were tested in this study. No differences in average daily gain, average daily feed intake or feed-to-gain ratio (P > 0.05) were observed among dietary treatments. Glycogen concentrations of longissimus dorsi (LD) muscle in DE3150 was higher than those in other groups (P < 0.05). The crude fat concentration of biceps femoris (BF) muscle in DE3250 tended to be higher than that in DE3150 and DE3100 groups (P < 0.05). Pigs in DE3250 and DE3200 had higher fiber density and smaller cross-sectional area of BF muscle than those in DE3150 (P < 0.05). Pigs in DE3150 had the highest Cu concentration in LD muscle compared with those in DE3200, DE3250 (P < 0.05). The C16:1 proportion of LD muscle was lower (P < 0.01) and C20:1 was higher (P < 0.05) in DE3050 than that in the other dietary treatments. The C18:3n6 and C20:3n6 proportions of BF muscle in DE3150 were higher than those in DE 3050, DE3200 and DE3250 (P < 0.05). For LD muscle, mRNA expressions of type I and IIa MyHC in group DE3150 were higher than other treatments (P < 0.01). The LD muscle in DE3150 expressed higher PPARd than in other groups (P < 0.01). Pigs in DE3100 expressed higher FOX1 than in DE3200 and DE3250 (P < 0.05). Sterol-regulatory element binding proteins (SREBPa) mRNA expression decreased linearly when dietary energy level increased in BF muscle (P < 0.01). In conclusion, a 200 kcal/kg decrease in digestible energy for 4 consecutive weeks did not affect growth performance of Xiangcun Black pigs. Furthermore, LD and BF muscle respond differently to dietary energy level, and meat quality was improved by the medium energy level during the finishing phase.

Pig adipose tissue of two different breeds and locations: morphology and Raman studies

According to the recent data, there are 4–5-local pig breeds left in Russia by now. Livni is among them. This breed is characterized by high fat content. Back fat has been analyzed earlier. We aimed to assess fat morphometrics from other localizations in pigs. Sacral, axillary, and perirenal fat samples from 6-month-old Duroc and Livni pig breeds were analyzed using morphological and Raman-based techniques. Livni adipocytes were characterized by dense packing with a polyhedron-like structure. In Duroc fat, they were more rounded (spherical). A “two-phase” cell disperse was identified in all samples. Fat cells in Livni pigs were bigger than those in the Duroc breed: 70–102%; 15–18 and 26% for sacral, axillary, and perirenal locations. Differences in the intensity of the Raman signal between the samples were found: in the samples of subcutaneous adipose tissue, more intense peaks were observed, which are responsible for unsaturation; the samples of Livni axillary fat were characterized by greater unsaturation than sacral fat. Livni and Duroc adipocytes differ from each other in form and size and the difference depends on location. Pork fat from local breeds is expected to have potentially more health protecting (for animals) and health promoting (for consumers) properties.

Assessing Genetic Diversity and Searching for Selection Signatures by Comparison between the Indigenous Livni and Duroc Breeds in Local Livestock of the Central Region of Russia

Indigenous pig breeds are mainly associated with the adaptive capacity that is necessary to respond adequately to climate change, food security, and livelihood needs, and natural resources conservation. Livni pigs are an indigenous fat-type breed farmed in a single farm in the Orel region and located in the Central European part of the Russian Federation. To determine the genomic regions and genes that are affected by artificial selection, we conducted the comparative study of two pig breeds with different breeding histories and breeding objectives, i.e., the native fat-type Livni and meat-type Duroc breeds using the Porcine GGP HD BeadChip, which contains ~80,000 SNPs. To check the Livni pigs for possible admixture, the Landrace and the Large White breeds were included into the study of genetic diversity as these breeds participated in the formation of the Livni pigs. We observed the highest level of genetic diversity in Livni pigs compared to commercial breeds (UHE = 0.409 vs. 0.319–0.359, p < 0.001; AR = 1.995 vs. 1.894–1.964, p < 0.001). A slight excess of heterozygotes was found in all of the breeds. We identified 291 candidate genes, which were localized within the regions under putative selection, including 22 and 228 genes, which were specific for Livni and Duroc breeds, respectively, and 41 genes common for both breeds. A detailed analysis of the molecular functions identified the genes, which were related to the formation of meat and fat traits, and adaptation to environmental stress, including extreme temperatures, which were different between breeds. Our research results are useful for conservation and sustainable breeding of Livni breed, which shows a high level of genetic diversity. This makes Livni one of the valuable national pig genetic resources.

Effect of guanidine acetic acid on meat quality, muscle amino acids, and fatty acids in Tibetan pigs

This study investigated the effects of guanidine acetic acid (GAA) supplementation on growth performance, carcass traits, and meat quality in Tibetan pigs. A total of 18 male Tibetan pigs (21.35 ± 0.99 kg) were randomly assigned to the control (basal diet) and GAA (basal diet + 800 mg/kg GAA) groups for 125 days. Growth performance, carcass traits, and meat quality in pigs, and the chemical composition of Longissimus thoracis (LT) were not altered by GAA. In LT, compared to the control group, dietary GAA increased the superoxide dismutase activity, transcripts of stearoyl CoA desaturase (SCD) and fatty acid synthase (FAS), and contents of glutamate, glutamine, C24:0, C20:3n-6, C20:4n-6, and polyunsaturated fatty acids (P < 0.05), but it decreased the malondialdehyde content (P < 0.001). In back fat, dietary GAA reduced the transcript of peroxisome proliferator-activated receptor γ (PPARγ) and the contents of C10:0, C12:0, C14:0, and C16:0 (P < 0.05), whereas it increased the contents of C22:0, C20:1, C22:1, C24:1, C20:2, C20:3n-3, and C22:2 (P < 0.05). These findings will provide a basis for high-quality Tibetan pork production.

SINE Insertion May Act as a Repressor to Affect the Expression of Pig LEPROT and Growth Traits

Retrotransposon is an important component of the mammalian genome. Previous studies have shown that the expression of protein-coding genes was affected by the insertion of retrotransposon into the proximal genes, and the phenotype variations would be related to the retrotransposon insertion polymorphisms (RIPs). In this study, leptin (LEP), leptin receptor (LEPR), and leptin receptor overlapping transcript (LEPROT), which play important roles in the regulation of fat synthesis and body weight, were screened to search for the RIPs and their effect on phenotype and gene expression, as well as to further study the function of the insertion. The results showed that three RIPs located in intron 1 of LEPROT and intron 2 and 21 of LEPR were identified, and they were all SINEA1, which was one type of retrotransposon. The SINE insertion at the LEPROT was the dominant allele in native pig breeds. The age of 100 kg body weight of SINE+/+ Large White individuals was significantly higher than those of SINE+/− and SINE−/− individuals (p < 0.05). The LEPROT gene expression in the liver and suet of 30-day-old SINE−/− Sujiang piglets were significantly higher than those of SINE+/+ and SINE+/− piglets (p < 0.01). The dual-luciferase reporter gene assay showed that SINE insertion in PK15 and 3T3-L1 cells significantly reduced the promoter activity of the LEPROT gene (p < 0.01). Therefore, SINE insertion can be a repressor to reduce the expression of LEPROT and could be a useful molecular marker for assisted selection of growth traits in pig breeding.

Age Evolution of Lipid Accretion Rate in Boars Selected for Lean Meat and Duroc Barrows

Fatty acid (FA) deposition in growing–fattening pigs is mainly based on endogenous lipid synthesis, but also direct FA incorporation from the diet. To evaluate the direct fat incorporation rates and the endogenous desaturation action of the stearoyl-CoA desaturase (SCD) enzyme, a deuterium (D)-labeled saturated FA (d35-C18:0) was added to the diet. Sixteen three-way (3W) crossbred boars, and thirty-two purebred Duroc barrows homozygous for the SCD single nucleotide polymorphism rs80912566 (16 CC/16 TT), were used. Half of the animals of each genotype belonged to the growing and fattening phases. The fractional incorporation rate (FIR) of dietary fat in growing pigs was generally higher in adipose tissues, whereas in fattening pigs it was higher in the liver. Duroc pigs exhibited lower FIRs than 3W pigs, suggesting lower rates of endogenous synthesis by 3W pigs. Real fractional unsaturation rates (FURs) increased with age by the higher FIRs in 3W pigs and the de novo synthesis pathway in Duroc genotypes. Moreover, pigs carrying the SCD_T allele showed more enhanced oleic acid biosynthesis than Duroc CC pigs. In conclusion, suitable feeding protocols should be designed for each pig type to optimize production traits, considering that the metabolic pathway of FA for its deposition may differ.

Instrumental and Sensory Analyses of Salami from Autochthonous and Conventional Pig Breeds

Typical salami produced from Mora Romagnola (MR), an autochthonous pig breed extensively farmed within a geographically confined Italian area, are food products of commercial interest. This investigation aimed to highlight elements for the recognition and authentication of such typical salami. Five MR salami were analyzed using a sensory and instrumental approach, and the results were compared with those from eight salami made from a conventional pig breed. The sensory profiles were defined through attributes such as seasoning, pepper, garlic, fermented etc.; no differences in the products ascribable to the pig breed were highlighted. By analyzing volatile compounds, 33 molecules were detected; significant differences were found among samples, probably related to processing methods. Color differences between MR and conventional salami were identified by an electronic eye. According to instrumental texture analysis, large variability among the MR samples was detected, probably related to different types of salami (recipe, casing, size, ripening). Correlations were found among the sensory results, volatile compounds, and textural properties of the samples. Most differences do not appear to be specifically related to MR breed; only red color intensity evaluated by an electronic eye showed a correlation with breed, i.e., MR salami. This study highlights the large variability among the salami analyzed.

Effects of age on subcutaneous adipose tissue proteins in Chinese indigenous Ningxiang pig by TMT-labeled quantitative proteomics

Adipose tissue not only affects meat quality and animal productivity, but also participates in inflammation and immunity. Ningxiang pig is famous for their excellent meat quality, disease resistance and tolerance of roughage. It is not yet well known how proteins in adipose tissue is dynamically regulated during the growth of Ningxiang pig. This report studies the proteomic changes in subcutaneous adipose tissue in Ningxiang pigs to gain a better understanding of the molecular mechanism of fat development during the growth period. By TMT-labeled quantitative proteomic analysis of subcutaneous adipose tissue of 9 purebred Ningxiang pigs of different ages, we identified 2533 unique proteins and 716 differentially abundant proteins (DAPs), of which more than half of the DAPs were concentrated in the 90d-210d period. Retrograde endocannabinoid signaling was only significantly enriched in DAPs of N90d vs N30d, Alcoholism and Graft-versus-host disease were only significantly enriched in DAPs of N210d vs N90d. Proteins related to dilated cardiomyopathy was found to be an important pathway in fat development and lipid metabolism. A variety of novel DAPs involved in maintaining mitochondrial function and cell viability, such as NDUFS6, SDHB, COX5A, ATP5D and TNNT1, which play a role in controlling the prediction networks, may indirectly regulate the development and functional maintenance of adipocytes. SIGNIFICANCE: These age-dependent DAPs discovered in this study may help expand the understanding of the molecular mechanisms of the development, function maintenance and transformation of adipose tissue in Ningxiang pig for developing new strategies for improving meat quality and pig breeding in the future.

Identification of Potential Candidate Genes From Co-Expression Module Analysis During Preadipocyte Differentiation in Landrace Pig

Preadipocyte differentiation plays an important role in lipid deposition and affects fattening efficiency in pigs. In the present study, preadipocytes isolated from the subcutaneous adipose tissue of three Landrace piglets were induced into mature adipocytes in vitro. Gene clusters associated with fat deposition were investigated using RNA sequencing data at four time points during preadipocyte differentiation. Twenty-seven co-expression modules were subsequently constructed using weighted gene co-expression network analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed three modules (blue, magenta, and brown) as being the most critical during preadipocyte differentiation. Based on these data and our previous differentially expressed gene analysis, angiopoietin-like 4 (ANGPTL4) was identified as a key regulator of preadipocyte differentiation and lipid metabolism. After inhibition of ANGPTL4, the expression of adipogenesis-related genes was reduced, except for that of lipoprotein lipase (LPL), which was negatively regulated by ANGPTL4 during preadipocyte differentiation. Our findings provide a new perspective to understand the mechanism of fat deposition.

Carcass Composition and Physicochemical Characteristics of Meat from Pork Chains Based on Native and Hybrid Pigs

The purpose of the research was to investigate the carcass composition, meat quality and chemical composition of pigs from two pork chains for the production of traditional dry/cured products in Croatia. The trial involved 24 Black Slavonian barrows reared outdoors (NAT chain) and 24 PIC hybrid barrows kept under industrial conditions (INT chain); all animals were raised to 160 kg of live weight. After slaughter, carcass and meat quality traits were measured and samples for chemical composition were taken. After that, a full dissection of the carcasses was performed. The pigs from the INT pork chain had leaner carcasses, higher bone percentages, and lower fatness levels than the NAT carcasses. Pigs from the NAT chain exhibited a more desirable meat quality. No differences were found in moisture, and samples from the INT chain exhibited higher collagen and protein percentage. Muscles from the NAT chain had higher IMF and MUFA levels, and the SFA content was lower than in INT pork. Despite the superior carcass traits of the pigs from the INT chain, pigs from the NAT chain demonstrated better suitability for the production of dry/cured products.

Genes Related to Fat Metabolism in Pigs and Intramuscular Fat Content of Pork: A Focus on Nutrigenetics and Nutrigenomics

Simple Summary

The intramuscular fat (IMF) or marbling is an essential pork sensory quality that influences the preference of the consumers and premiums for pork. IMF is the streak of visible fat intermixed with the lean within a muscle fibre and determines sensorial qualities of pork such as flavour, tenderness and juiciness. Fat metabolism and IMF development are controlled by dietary nutrients, genes, and their metabolic pathways in the pig. Nutrigenetics explains how the genetic make-up of an individual pig influences the pig’s response to dietary nutrient intake. Differently, nutrigenomics is the analysis of how the entire genome of an individual pig is affected by dietary nutrient intake. The knowledge of nutrigenetics and nutrigenomics, when harmonized, is a powerful tool in estimating nutrient requirements for swine and programming dietary nutrient supply according to an individual pig’s genetic make-up. The current paper aimed to highlight the roles of nutrigenetics and nutrigenomics in elucidating the underlying mechanisms of fat metabolism and IMF deposition in pigs. This knowledge is essential in redefining nutritional intervention for swine production and the improvement of some economically important traits such as growth performance, backfat thickness, IMF accretion, disease resistance etc., in animals.

Abstract

Fat metabolism and intramuscular fat (IMF) are qualitative traits in pigs whose development are influenced by several genes and metabolic pathways. Nutrigenetics and nutrigenomics offer prospects in estimating nutrients required by a pig. Application of these emerging fields in nutritional science provides an opportunity for matching nutrients based on the genetic make-up of the pig for trait improvements. Today, integration of high throughput “omics” technologies into nutritional genomic research has revealed many quantitative trait loci (QTLs) and single nucleotide polymorphisms (SNPs) for the mutation(s) of key genes directly or indirectly involved in fat metabolism and IMF deposition in pigs. Nutrient–gene interaction and the underlying molecular mechanisms involved in fatty acid synthesis and marbling in pigs is difficult to unravel. While existing knowledge on QTLs and SNPs of genes related to fat metabolism and IMF development is yet to be harmonized, the scientific explanations behind the nature of the existing correlation between the nutrients, the genes and the environment remain unclear, being inconclusive or lacking precision. This paper aimed to: (1) discuss nutrigenetics, nutrigenomics and epigenetic mechanisms controlling fat metabolism and IMF accretion in pigs; (2) highlight the potentials of these concepts in pig nutritional programming and research.

Combining computer vision score and conventional meat quality traits to estimate the intramuscular fat content using machine learning in pigs

Intramuscular fat content (IMF%) is an important factor that affects the quality of pork. The traditional testing method (Soxhlet extraction) is accurate; however, it has a long preprocessing time. In this study, a total of 1481 photographs of 200 pigs' loin muscles were used to obtain a computer vision score (IIMF %). Then, actual IMF%, meat color, marbling score, pH value, and drip loss of 200 pigs were measured. Stepwise regression (SR) and gradient boosting machine (GBM) were used to construct the estimation model of IMF%. The results showed that the correlation coefficients between IMF% and IIMF%, marbling score, backfat thickness, percentage of moisture (POM), and pH value were 0.68, 0.64, 0.48, 0.45, and 0.25, respectively. The model accuracies of SR and GBM base on residuals distribution were 0.875 and 0.89, respectively. This study presents a method for estimating IMF% using computer vision technology and meat quality traits.

The Effect of Rearing Conditions on Carcass Traits, Meat Quality and the Compositions of Fatty Acid and Amino Acid of LTL in Heigai Pigs

Simple Summary

People’s demand for meat consumption has transformed from quantity to quality. The rearing condition is one of the factors affecting meat quality. However, the effects of different rearing conditions on the production of Chinese indigenous pig breeds are still barely understood. In this study, Heigai pigs (a Chinese indigenous pig breed) were raised in the indoor feeding farm and the grazing farm to investigate the effects of different rearing conditions on carcass traits, meat quality and the compositions of fatty acid and amino acid. Grazing farm pigs tended to increase shear force, while significantly increasing the saturated fatty acid ratio and decreasing the unsaturated fatty acid ratio to alter the composition of fatty acids of longissimus thoracis et lumborum. The present study provides an experimental reference for regulating the production of superior meat quality pork of Chinese local breed pigs.

Abstract

The present study evaluates the influence of captivity and grazing rearing conditions on the carcass traits, meat quality and fatty acid profiles of Heigai pigs. Ten Heigai pigs with market weight were randomly selected from both the indoor feeding farm and outdoor grazing farm groups (FF and GF; five pigs per group) for measuring production performance. The results showed that the shear force of longissimus thoracis et lumborum (LTL) in the GF group tended to increase (p = 0.06), and triglyceride and cholesterol contents in LTL and psoas major muscle (PMM) of the GF group significantly increased and decreased, respectively (p < 0.05). The proportion of saturated fatty acids (SFA) was significantly increased (p < 0.05) in the GF group. Meanwhile, the ratios of unsaturated fatty acid (UFA), polyunsaturated fatty acid (PUFA), monounsaturated fatty acid (MUFA) and the content of flavor amino acid of the LTL in the GF group were significantly decreased (p < 0.05). The GF upregulated the expression of MyHC-IIb and lipogenic genes, such as GLUT4 and LPL (p < 0.05), in LTL and PMM, but downregulated the expression of MyHC-I, MyHC-IIa, PPARγ and leptin (p < 0.05). In conclusion, these results suggested that the different rearing conditions can alter the meat qualities by mediating the muscle fiber type and lipid metabolism of Heigai pigs.

Review: Pork quality attributes from farm to fork. Part I. Carcass and fresh meat

This work considers all factors along the production chain from farm to fork influencing the quality of fresh pork and processed products. Pork quality is multidimensional and comprises various attributes: commercial value of carcasses, meat organoleptic, nutritional, technological (i.e. suitability for processing and storage) properties, convenience, and societal image. The latter denotes cultural, ethical (including animal welfare) and environmental dimensions related to pork production, including geographical origin, all of which influence societal perceptions for pork. This review covers the impact of production factors, slaughter methods, carcass processing, and post mortem ageing on fresh meat quality. The impact on pork quality from some of these factors are now well documented and clearly established (e.g. genetics and pork technological attributes; diet and lipid profile; preslaughter and slaughter conditions and pork technological or organoleptic attributes…). Gaps in scientific knowledge are also identified, including the need for a better understanding of regulatory pathways for oxidative stress in vivo and post mortem that can contribute to optimise pork organoleptic and nutritional attributes and its suitability for processing and storage. This review highlights the strong interactions between primary production factors on pork quality attributes. Interactions are particularly marked in alternative production systems, in which synergies between factors can lead to specific quality characteristics that can be used to market pork at a premium as branded products. There are also antagonisms between quality attributes, namely between carcass commercial value and pork technological and organoleptic properties, between nutritional attributes and processing and storage suitability of fat tissues, between societal image and pork technological attributes in outdoor production systems, and between societal image (better welfare) and organoleptic attributes (risk for boar taint) in entire male production. Further research is needed to better understand the effects of some specific production factors and their interactions on quality attributes. A holistic approach with the use of multicriteria analyses can help to work out the trade-offs between pork quality attributes and between stakeholders (farmer, slaughterhouse or processing plant, consumers, citizens …) whose priorities may differ.

Effects of Different Levels of Inclusion of Apulo-Calabrese Pig Meat on Microbiological, Physicochemical and Rheological Parameters of Salami during Ripening

This study focused on the characterization of salami produced with meat from different pig breeds. The aim consisted in evaluating the added value of the inclusion of Apulo-Calabrese meat in the production of salami, which was characterized by production until the end of maturation (1, 30, 60, and 120 days). The experimental design involved three types of salami, two of which were produced by partial inclusion of 50 and 75% of the Italian breed pork meat (S50 and S75, respectively). Physicochemical (pH, a_w, fatty acid analysis, and malondialdehyde concentration), rheological parameters (texture analyses and color measurement), and bacterial biodiversity were evaluated. Results showed that the partial inclusion of Apulo-Calabrese meat influences the fatty acid profile of final products, which were characterized by a higher percentage of monounsaturated fatty acids compared to traditional salami; however, due to the high content of unsaturated fatty acids, S50 and S75 showed higher values of secondary lipid oxidation up to the 120th day. The linoleic and palmitic acid content significantly affected hardness and brightness. Overall, the ripening process was able to control the microbiological profile and the S50 formulation appeared as a suitable choice that could satisfy consumers for nutritional expectations and sensory profiles.

Determination of the Heterogeneity of Intramuscular Fat and Visceral Adipose Tissue From Dezhou Donkey by Lipidomics and Transcriptomics Profiling

Intramuscular fat (IMF) and visceral adipose tissue (VAT) are both lipids, but have significantly different deposition processes. Furthermore, the heterogeneity of lipid molecular characteristics and mechanisms is unclear. Accordingly, this study used non-targeted lipidomics and transcriptomics to analyze the lipid profiles and metabolism of longissimus dorsi muscle (LDM) and VAT from donkeys. A total of 1,146 and 1,134 lipids belonging to 18 subclasses were identified in LDM and VAT, respectively, with LDM having higher glycerophospholipid (GP) and lower glycerolipid (GL) contents. Polyunsaturated fatty acids (PUFAs) were distributed preferentially at the sn-1 positions in triglycerides (TGs), and sn-2 positions in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The percentage PUFA content in TGs was significantly lower in LDM than in VAT, while the opposite trend was observed for PUFAs in PC and PE. A total of 110 different lipid molecules (72 downregulated and 38 upregulated) were identified in LDM compared with VAT, of which 11 were considered potential lipid markers. These different lipids were involved in 17 metabolic pathways, including GL and GP metabolisms. Of the 578 differentially expressed genes screened, 311 were downregulated and 267 were upregulated in LDM compared with VAT. Enriched ontology analysis of the differentially expressed genes mainly involved sphingolipid signaling pathways, and GP, GL, and sphingolipid metabolisms. Overall, lipidomics and transcriptomics indicated differences in lipid profiles and metabolism in LDM and VAT, providing new perspectives for the study of heterogeneity in IMF and VAT.

RNF20 affects porcine adipocyte differentiation via regulation of mitotic clonal expansion

Objectives

RNF20 is recognized as a main E3 ligase for monoubiquitination of histone H2B at lysine 120 (H2Bub). The critical role of RNF20 and H2Bub in various molecular events, such as DNA replication, RNA transcription, and DNA damage response, has been widely investigated and documented. However, its role in porcine adipogenesis remains unknown. In this study, we aimed to clarify the effect of RNF20 on porcine preadipocyte differentiation.

Materials and Methods

Backfat tissues from fat‐type pigs (Bama and Meishan) and lean‐type pigs (Yorkshire and Landrace) were collected to detect the expression level of RNF20. Preadipocytes were isolated from Bama piglets and induced to differentiation. Small interfering RNAs were applied to deplete RNF20. Oil Red O staining, quantitative real‐time PCR, RNA‐seq, Western blot analysis, and EdU assays were performed to study the regulatory mechanism of RNF20 during adipogenesis.

Results

We found that the expression levels of RNF20 and H2Bub were significantly higher in backfat tissues from fat‐type pigs than in those from lean‐type pigs. Consistently, the significantly induced expression of RNF20 and H2Bub was also observed in porcine differentiated adipocytes. In addition, knockdown of RNF20 greatly inhibited porcine adipogenesis, as evidenced by dramatically decreased lipid droplet formation and lower expression levels of adipogenic transcription masters in RNF20 knockdown cells. Mechanistically, the depletion of RNF20 decreases the cell proliferation and the level of p‐C/EBPβ via the Ras‐Raf‐MEK1/2‐ERK1/2 cascade pathway at the mitotic clonal expansion phase and therefore suppresses cell differentiation.

Conclusions

Our results demonstrate that RNF20 is required for porcine preadipocyte differentiation.

Feeding Crude Glycerin to Finishing Iberian Crossbred Pigs: Effects on Growth Performance, Nutrient Digestibility, and Blood Parameters

A total of 192 Iberian × Duroc pigs kept under intensive conditions were used to investigate the effects of feeding crude glycerin on growth performance, nutrient digestibility, and blood parameters. Animals were blocked by initial body weight (96.0 ± 11.3 kg) and allotted to pens (16 pigs per pen). Pens were assigned randomly to one of three dietary treatments (four pens per treatment). Dietary treatments contained 0, 5, or 10% of crude glycerin proportionally substituting for wheat (G0, G5, and G10, respectively). Diets were formulated to be isoenergetic and isoaminoacidic. No significant effect of crude glycerin was observed on average daily gain, average feed intake, or feed conversion ratio. The apparent total tract digestibility of dry matter, organic matter, and crude protein was no different between treatments. Total serum protein, albumin, glucose, insulin, and IGF-1 were not affected by glycerin inclusion. In conclusion, crude glycerin up to 100 g/kg can be included in the diets of finishing Iberian crossbred pigs without any negative effect on growth performance, digestibility, or serum metabolic parameters.

Comparative characterization of lipids and volatile compounds of Beijing Heiliu and Laiwu Chinese black pork as markers

Chinese black pork is preferred by consumers due to its unique organoleptic characteristics, which are closely related to lipids and volatiles. The primary aim of this study was to reveal key lipids and volatiles for the differentiation of Duroc × (Landrace × Yorkshire) (DLY), and Beijing Heiliu and Laiwu black (BHLB) pork. Here, lipid and volatile profiles were comprehensively characterized and compared using untargeted lipidomic and volatilomic analysis. The BHLB pork showed higher intramuscular fat content (p < 0.05). The content of total monounsaturated fatty acids, along with C16:1, C17:1, C18:1, and C20:1, was higher in BHLB pork compared with DLY pork (p < 0.05). Lipidomic analysis showed that DLY and BHLB pork significantly differed in lipids at the class and molecular levels. The BHLB pork had significantly more triglyceride and less lysophosphatidylcholine compared with DLY pork (p < 0.05). In positive and negative modes, 34 and 21 potential lipid markers, respectively, were selected for the discrimination of DLY and BHLB pork. In addition, volatilomic analysis showed that DLY and BHLB pork were well distinguished, and 13 volatiles were considered as potential discriminatory markers. Our findings provide a comprehensive lipidomic and volatilomic profiles characteristic of BHLB pork and will hopefully provide an important basis for the effective identification of Chinese black pork.

Evolution of viscera and muscle fractional protein synthesis rate in lean meat selected hybrids and castrated Duroc pigs fed under moderate crude protein restriction

Differences in producing performance and organoleptic meat characteristics among pig genotypes and/or producing types are widely known. These parameters are also subjected to the animal's development, feeding and management. Detailed knowledge of the effects of production phase (PP), pig producing type (PT), dietary protein availability and their interactions on nutrient digestibility, nitrogen balance and protein metabolism is essential information to improve precision feeding techniques. The experiment was a 2 (PP) × 2 (PT) × 2 (diet) factorial design conducted with 32 male pigs, 16 entire F2 pigs progeny of Pietrain sires and Duroc × Landrace dams, and 16 castrated purebred Durocs belonging to two production phases (growing: 29.5 ± 3.19 v. fattening: 88.6 ± 6.26 kg BW), and assigned to one of two dietary CP levels, either standard (SP: 17% in growing and 15% in fattening) or low (LP: 15% in growing and 13% in fattening). Viscera and muscle fractional protein synthesis rates (FSRs; %/day) were conducted through a single infusion of 15% L-[ring-²H₅]-phenylalanine, with subsequent blood sampling from 12 to 40 min, and sample collection of liver, duodenum, biceps femoris and longissimus dorsi skeletal muscles after sacrifice. Fattening animals acquired a greater feed ingestion capacity, average daily gain (P < 0.01) and apparent ileal digestibility, whereas growing pigs showed higher FSRs in both viscera (duodenum and liver) and in longissimus dorsi. F2 pigs showed higher average daily gain, nitrogen retention rates and FSR in liver and longissimus dorsi (P < 0.01). Nevertheless, apparent ileal digestibility in all essential amino acids was lower in F2 compared with Duroc pigs (P < 0.05). Protein metabolism was barely influenced by dietary CP content, although animals fed LP registered the lowest apparent ileal digestibility for CP and also for most of the essential amino acids compared with SP-fed pigs. This information may reveal differences in amino acid requirements between both PTs, with Duroc pigs receiving excess of dietary amino acids.

Genomic Regions and Candidate Genes Linked to Capped Hock in Pig

Capped hock affects the exterior of pedigree pigs, making them unsalable and resulting in a negative impact on the efficiency of pig-breeding centers. The purpose of this paper was to carry out pilot studies aimed at finding genomic regions and genes linked to the capped hock in pigs. The studies were carried out on Landrace pigs (n = 75) and Duroc pigs (n = 70). To identify genomic regions linked to capped hock in pigs, we used smoothing FST statistics. Genotyping was performed with GeneSeek^® GGP Porcine HD Genomic Profiler v1 (Illumina Inc, San Diego, CA, USA). The research results showed 70 SNPs linked to capped hock in Landrace (38 SNPs) and Duroc (32 SNPs). The identified regions overlapped with QTLs related with health traits (blood parameters) and meat and carcass traits (fatness). In total, 31 genes were identified (i.e., 17 genes in Landrace, 14 genes in Durocs). Three genes appeared in both the Landrace and Duroc groups, including A2ML1 (SSC5), ROBO2 (SSC13), and MSI1 (SSC14). We identified genomic regions directly or indirectly linked to capped hock, which thus might contribute to identifying genetic variants and using them as genetic markers in pig breeding.

Transcriptomic Profiling of Skeletal Muscle Reveals Candidate Genes Influencing Muscle Growth and Associated Lipid Composition in Portuguese Local Pig Breeds

Simple Summary

Screening and interpretation of differentially expressed genes and associated biological pathways was conducted among experimental groups with divergent phenotypes providing valuable information about the metabolic events occurring and identification of candidate genes with major regulation roles. This comparative transcriptomic analysis includes the first RNA-seq analysis of the Longissimus lumborum muscle tissue from two Portuguese autochthonous pig breeds with different genetic backgrounds, Alentejano and Bísaro. Moreover, a complementary candidate gene approach was employed to analyse, by real time qPCR, the expression profile of relevant genes involved in lipid metabolism, and therefore with potential impacts on meat composition. This study contributes to explaining the biological basis of phenotypical differences occurring between breeds, particularly the ones related to meat quality traits that affect consumer interest.

Abstract

Gene expression is one of the main factors to influence meat quality by modulating fatty acid metabolism, composition, and deposition rates in muscle tissue. This study aimed to explore the transcriptomics of the Longissimus lumborum muscle in two local pig breeds with distinct genetic background using next-generation sequencing technology and Real-Time qPCR. RNA-seq yielded 49 differentially expressed genes between breeds, 34 overexpressed in the Alentejano (AL) and 15 in the Bísaro (BI) breed. Specific slow type myosin heavy chain components were associated with AL (MYH7) and BI (MYH3) pigs, while an overexpression of MAP3K14 in AL may be associated with their lower loin proportion, induced insulin resistance, and increased inflammatory response via NFkB activation. Overexpression of RUFY1 in AL pigs may explain the higher intramuscular (IMF) content via higher GLUT4 recruitment and consequently higher glucose uptake that can be stored as fat. Several candidate genes for lipid metabolism, excluded in the RNA-seq analysis due to low counts, such as ACLY, ADIPOQ, ELOVL6, LEP and ME1 were identified by qPCR as main gene factors defining the processes that influence meat composition and quality. These results agree with the fatter profile of the AL pig breed and adiponectin resistance can be postulated as responsible for the overexpression of MAP3K14′s coding product NIK, failing to restore insulin sensitivity.

Rice bran oil emulgel as a pork back fat alternate for semi-dried fish sausage

The objective of this study was to investigate the effects of rice bran oil emulsion filled gels (EG) substitution for pork back fat on the characteristics of Chinese style semi-dried tilapia sausage (CFS). EG prepared using different gelling agents and processing conditions were used as pork back fat alternate in the CFS. From the results, physical, chemical and microstructural qualities of CFS were governed by the type of EG incorporated. Regarding the overall quality, CFS formulated with carrageenan-EG was classified as an optimal formula. CFS added with carrageenan-EG showed a superior oxidative stability, color preservation, and water holding capacity compared to the control during vacuum packaged storage at room temperature for 20 days. Thiobarbituric acid reactive substances (TBARS) and microbial quality of both formulae remained in the acceptable level (TBARS < 1 mg/kg and total plate count < 4 log CFU/g) throughout the storage. Therefore, the carrageenan based EG substitution for pork back fat is a promising avenue for the production of the CFS where a high saturated animal fat was substituted by vegetable oil.