Current feeding strategies to improve pork intramuscular fat content and its nutritional quality

Whole-Transcriptome Analysis Sheds Light on the Biological Contexts of Intramuscular Fat Deposition in Ningxiang Pigs

The quality of pork is significantly impacted by intramuscular fat (IMF). However, the regulatory mechanism of IMF depositions remains unclear. We performed whole-transcriptome sequencing of the longissimus dorsi muscle (IMF) from the high (5.1 ± 0.08) and low (2.9 ± 0.51) IMF groups (%) to elucidate potential mechanisms. In summary, 285 differentially expressed genes (DEGs), 14 differentially expressed miRNAs (DEMIs), 83 differentially expressed lncRNAs (DELs), and 79 differentially expressed circRNAs (DECs) were identified. DEGs were widely associated with IMF deposition and liposome differentiation. Furthermore, competing endogenous RNA (ceRNA) regulatory networks were constructed through co-differential expression analyses, which included circRNA-miRNA-mRNA (containing 6 DEMIs, 6 DEGs, 47 DECs) and lncRNA-miRNA-mRNA (containing 6 DEMIs, 6 DEGs, 36 DELs) regulatory networks. The circRNAs sus-TRPM7_0005, sus-MTUS1_0004, the lncRNAs SMSTRG.4269.1, and MSTRG.7983.2 regulate the expression of six lipid metabolism-related target genes, including PLCB1, BAD, and GADD45G, through the binding sites of 2-4068, miR-7134-3p, and miR-190a. For instance, MSTRG.4269.1 regulates its targets PLCB1 and BAD via miRNA 2_4068. Meanwhile, sus-TRPM7_0005 controls its target LRP5 through ssc-miR-7134-3P. These findings indicate molecular regulatory networks that could potentially be applied for the marker-assisted selection of IMF to enhance pork quality.

Coculture with porcine luteal cells during in vitro porcine oocyte maturation affects lipid content, cortical reaction and zona pellucida ultrastructure

CONTEXT

In pigs, in vitro fertilisation (IVF) is associated with high polyspermy rates, and for this reason, in vitro embryo production (IVP) is still an inefficient biotechnology. Coculture with somatic cells is an alternative to improve suboptimal in vitro maturation (IVM) conditions.

AIM

This study was conducted to test a coculture system of porcine luteal cells (PLC) and cumulus-oocyte complexes (COC) to improve oocyte metabolism.

METHODS

COC were matured in vitro with PLC. Oocyte lipid content, mitochondrial activity, zona pellucida (ZP) digestibility and pore size, cortical reaction and in vitro embryo development were assessed.

KEY RESULTS

Coculture reduced cytoplasmic lipid content in the oocyte cytoplasm without increasing mitochondrial activity. Although ZP digestibility and ZP pore number were not different between culture systems, ZP pores were smaller in the coculture. Coculture impacted the distribution of cortical granules as they were found immediately under the oolemma, and more of them had released their content in the ZP. Coculture with porcine luteal cells during IVM increased monospermic penetration and embryo development after IVF.

CONCLUSIONS

The coculture of COC with PLC affects the metabolism of the oocyte and benefits monospermic penetration and embryo development.

IMPLICATIONS

The coculture system with PLC could be an alternative for the conventional maturation medium in pigs.

Effect of dietary fat on proximal composition, sensorial analysis and shelf life of a traditional Spanish cooked pork product "Lomo de Sajonia" from Iberian pork

This study aims to evaluate the effect of different dietary fat sources on the quality of a Spanish-cooked meat product Lomo de Sajonia (LSA) and its shelf-life. Forty loins were selected from Iberian pigs fed four dietary treatments containing pork fat (G-1), Greedy-Grass Olive® (GGO) (enriched oleic-acid oil) (G-2), G-2 and high oleic sunflower (G-3), and G-3 plus a mixture of commercial organic acids (Bioll®) (G-4). Loins were manufactured to obtain LSA, and the quality and sensorial attributes were assessed. The shelf life was established according to microbial count and sensorial analysis, which was packed in a modified atmosphere and stored under retail conditions. All meat quality parameters of LSA remained stable in all groups, except fat content and overall liking, which showed the highest values for G-2 LSA. Regarding the shelf life, sensorial attributes remained acceptable in all groups during storage time, while a delay in microbial growth was recorded for the LSA of G-3. According to the results, including GGO in Iberian pig diets could enhance LSA traits, possibly linked to increased assimilation compared with conventional fat sources. However, adding organic acids to the diet did not have the expected effect on improving the shelf life of the LSA.

Performance and meat quality in pigs fed hydrolysable tannins from Tara spinosa

This study aimed to assess the effect of dietary tara (Tara spinosa (Feuillée ex Molina) Britton & Rose) hydrolysable tannins on performance and meat quality of finishing pigs. Twenty barrows (crossbred PIC × Piétrain; age: 125 ± 5 d; bodyweight: 60.8 ± 3.89 kg) were randomly assigned to two groups and fed ad libitum for 7 weeks a control diet (CON) or a diet supplemented with 10 g/kg of tara tannins (TAT), respectively. No differences (P > 0.10) on growth performance and carcass traits were observed between the two groups. Meat fatty acid profile was not affected (P > 0.10) by the diet, but the content of C22:5 n-3 tended to be lower (P = 0.079) in TAT pork. Dietary tannins tended to reduce (P = 0.095) meat cholesterol. The diet had no effect (P > 0.10) on fat-soluble antioxidant vitamins, hydrophilic antioxidant capacity, catalase activity, and glutathione peroxidase activity. Superoxide dismutase activity tended to be lower (P = 0.087) in TAT meat than in CON meat. Dietary tannins did not affect (P > 0.10) backfat and meat color development during 6 days of refrigerated storage, but TAT meat tended to be darker (P = 0.082). Meat from pigs fed tara tannins showed lower (P = 0.028) hydroperoxides content and a tendency toward lower conjugated dienes (P = 0.079) and malondialdehyde (P = 0.084) contents. Also, dietary tannins delayed lipid oxidation in meat subjected to oxidative challenges such as catalysis and cooking (P < 0.05). The positive effect of dietary tara hydrolysable tannins on lipid oxidation was likely due to their antioxidant and anti-inflammatory capacity, but it may have been mitigated by the high α-tocopherol content in meat.

Combined application of high-throughput sequencing and LC-MS-based lipidomics in the evaluation of microorganisms and lipidomics of restructured ham of different salted substitution

The optimization of processed meats through salt replacement using KCl and k-lactate may reduce the risk of chronic diseases through reduction in dietary sodium. The objective of this study was to investigate the changes and relationships between microbial and lipid metabolism during the fermentation of restructured duck ham with different salt substitutions. Lactobacillus and Staphylococcus were found to be the dominant bacterial species in the 30 % KCl + 70 % NaCl (w/w) and 25 % k-lactate + 75 % NaCl (w/w). The LefSe analysis showed that different biomarkers were present in different ham groups, and the PLS-DA showed that triglycerides (GL) and glycerophospholipids (GP) were the two classes with the highest abundance. Besides, the KEGG pathway analysis revealed that glycerophospholipid metabolism and triglyceride metabolism were also the main metabolic pathways. According to the correlation study, Staphylococcus, Halomonas, and Lactobacillus were mostly linked to the important metabolic pathways in restructured ham. Our findings serve as a foundation for quality assurance and product enhancement for low-salt restructured ham.

Circular RNA transcriptome across multiple tissues reveal skeletal muscle-specific circPSME4 regulating myogenesis

There are significant differences in meat production, growth rate and other traits between Western commercial pigs and Chinese local pigs. Comparative transcriptome approaches have identified many coding and non-coding candidate genes associated various traits. However, the expression and function of circular RNAs (circRNAs) in different pig tissues are largely unknown. In this study, we conducted a comprehensive analysis of the genome-wide circRNA expression profile across ten tissues in Luchuan (a Chinese local breed) and Duroc (a Western commercial breed) pigs. We identified a total of 56,254 circRNAs, of which 42.9 % were not previously annotated. We found that 33.7 % of these circRNAs were differentially expressed. Enrichment analysis revealed that differentially expressed circRNAs might contribute to the phenotypic differentiation between Luchuan and Duroc pigs. We identified 538 tissue-specific circRNAs, most of which were specifically expressed in the brain and skeletal muscle. Competitive endogenous RNA network analysis suggested that skeletal muscle-specific circPSME4 was co-expressed with MYOD1 and targeted by ssc-miR-181d-3p. Functional analysis revealed that circPSME4 knockdown could promote the proliferation and differentiation of myoblasts. Together, our findings provide valuable resources of circRNAs for animal breeding and biomedical research. We demonstrated that circPSME4 is a novel regulator of skeletal muscle development.

Dietary Ulva lactuca and CAZyme supplementation improve serum biochemical profile and hepatic composition of weaned piglets

Ulva lactuca is a seaweed with antinutritional cell wall for monogastrics. Carbohydrate-Active enZymes (CAZymes) supplementation can potentially cause its disruption. This study evaluates four diets: Ctrl-control diet; UL-control + 7% U. lactuca (wild caught, powdered form); ULR-UL + 0.005% Rovabio^® Excel AP; ULU-UL + 0.01% ulvan lyase on piglets' haematologic and serologic profiles, hepatic lipids and minerals. White blood cells and lymphocytes reached the highest values in piglets fed UL compared to control, and to control and ULR; respectively (P < 0.05). IgG levels were boosted by seaweed incorporation compared to control (P = 0.015). The glycaemic homeostasis was assured by the seaweed inclusion. Dietary seaweed decreased serum lipids (P < 0.001), with the exception of ULU, due to HDL-cholesterol increase (P < 0.001). Cortisol was decreased in ULR and ULU (P < 0.001). No systemic inflammation was observed (P > 0.05). While hepatic n-3 PUFA increased in piglets fed with seaweed diets due to increment of beneficial 22:5n-3 and 22:6n-3 fatty acids (P < 0.05), the opposite occurred for n-6 PUFA, PUFA/SFA and n-6/n-3 ratios (P < 0.05). Hepatic pigments were unchanged (P > 0.05). ULR reduced α-tocopherol levels (P = 0.036) and increased serum potassium levels (P < 0.001) compared to control. Seaweed contributed to overcome piglets' weaning stress, with some benefits of including CAZyme supplementation.

Improving Fatty Acid Profile in Native Breed Pigs Using Dietary Strategies: A Review

Meat from native-bred animals is growing in popularity worldwide due to consumers' perception of its higher quality than meat from industrial farms. The improvement in indigenous pork has been related to increased intramuscular and unsaturated fat and a reduced saturated fat content resulting in a healthy product with enhanced sensorial attributes. This manuscript aims to provide an overview offering useful information about the fat content and the fatty acid profile of different autochthonous pork. Fat content and fatty acid profile are greater in native than in industrial pig breeds, even though certain factors, such as genetics, nutrition, farming system, age, or slaughter weight, may influence these variations. Among that, studies on dietary strategies to improve these parameters have been evaluated. According to the results obtained, many natural ingredients could have a positive effect on the lipid profile when added to indigenous pigs' diets. This fact may promote autochthonous pork intake. Nevertheless, there is a wide range of potential natural ingredients to be added to the indigenous pig diet that needs to be evaluated.

Physicochemical, microbiological, and sensory characteristics of "Sui Wu'u" traditional pork products from Bajawa, West Flores, Indonesia

Background and Aim

Sui Wu'u is a traditional meat preservation product from Bajawa, a region in East Nusa Tenggara. It is made by mixing pork with salt and corn flour, which is then stored in a bamboo container (tuku) for months. After 6 months of storage, this study examined the physicochemical, microbiological, and sensory properties of Sui Wu'u.

Materials and Methods

Sui Wu'u products were prepared using the traditional recipe from the Bajawa community. Fresh pork (pork belly and backfat), corn flour, and salt were purchased from local/traditional markets at proportions of 65%, 30%, and 5%, respectively. The physicochemical, amino acid, fatty acid profile, microbiological, and sensory properties of Sui Wu'u were evaluated after being stored for 6 months in a bamboo container (tuku).

Results

The results indicated that these Sui Wu'u were mainly characterized by high-fat levels, followed by protein. The pH value, salt content, moisture content, and water activity were 4.72%, 1.72%, 6.11%, and 0.62%, respectively. Minerals (K, P, Se, and Zn) and vitamin B6, as well as amino acids, such as leucine, phenylalanine, lysine (essential amino acids), glycine, proline, glutamic acid, and alanine (non-essential amino acids), are present in Sui Wu'u. The fatty acid profile was dominated by monounsaturated fatty acids (MUFA) (21.69%), saturated fatty acids (SFA) (17.78%), and polyunsaturated fatty acids (PUFA) (5.36%). Monounsaturated fatty acids, oleic acid (C18:1n9) was the most abundant fatty acid in Sui Wu'u, followed by palmitic acid SFA (C16:0); MUFA stearic acid (C18:0); and PUFA linoleic (C18:2n-6). The microbiological characteristics of Sui Wu'u showed no detectable microorganisms (<10 CFU/g) for Salmonella, total E. coli and total Staphylococcus, and average values of 4.4 × 105 CFU/g for total microbes, which were still below the maximum limit of microbial contamination according to the regulations of the Food and Drug Supervisory Agency of the Republic of Indonesia. The sensory assessment indicated that panelists highly preferred (rated as very like) Sui Wu'u for all sensory attributes.

Conclusion

The physicochemical, microbiological, and sensory characteristics of Sui Wu'u after 6 months of storage indicated that it still provides essential nutrients for the body and is quite safe for consumption. The stability of Sui Wu'u's shelf life can be attributed to the appropriate combination of pork, salt, corn flour, bamboo packaging (tuku), and storage temperature. The high-fat content in Sui Wu'u can be reduced by increasing the proportion of lean meat. Ensuring strict sanitation during the manufacturing process, using high-quality pork, salt, corn flour, and proper packaging with bamboo can further improve the safety of Sui Wu'u for consumption.

Mutation c.-379 C>T in DGAT1 affects intramyocellular lipid content by altering MYOD1 binding affinity

Intramuscular fat (IMF) is one of the most important indexes of pork taste quality. Diacylglycerol acyltransferase 1 (DGAT1), belonging to the acyl-coenzyme A: DGAT enzymes family, is a rate-limiting enzyme responsible for the final step of triglyceride (TG) synthesis. It is involved in TG storage in skeletal muscle; however, the underlying mechanism is not well understood. This study aimed to uncover functional mutations that can influence DGAT1 expression and consequently affect IMF deposition in pork. Two experimental groups containing individuals with high and low IMF content (6.23 ± 0.20 vs. 1.25 ± 0.05, p < 0.01) were formed from 260 Duroc × Large White × Yorkshire (D × L × Y) cross-bred pigs. A novel SNP c.-379 C>T was uncovered in the DGAT1 gene using comparative sequencing with pool DNA of high- and low-IMF groups. The IMF content of CT genotype individuals (3.19 ± 0.11%) was higher than that of CC genotype individuals (2.86 ± 0.11%) when analyzing 260 D × L × Y pigs (p < 0.05). The DGAT1 expression levels revealed a significant positive correlation with IMF content (r = 0.33, p < 0.01). Luciferase assay revealed that the DGAT1 promoter with the c.-379 T allele has a higher transcription activity than that bearing the C allele in C2C12 myoblast cells, but not in 3T3-L1 pre-adipocytes. Online prediction followed by chromatin immunoprecipitation-polymerase chain reaction assay confirmed that myogenic determination factor 1 (MYOD1) binds to the DGAT1 promoter with the c.-379 C allele but not the T allele. In vitro experiments demonstrated that MYOD1 represses DGAT1 transcription and lipogenesis. As a muscle-specific transcription factor, MYOD1 can inhibit the transcription of DGAT1 with the c.-379 C allele in muscle cells. However, in the absence of MYOD1 binding to the mutated DGAT1 promoter with the c.-379 T allele, DGAT1 expresses at a higher level in the muscle cells of the c.-379 T genotype, leading to more intramyocellular lipid accumulation than in the muscle cells of the c.-379 C genotype. The SNP c.-379 C>T in the promoter region of the DGAT1 gene provides a promising molecular marker for improving pork IMF content without affecting other fat depots.

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.

Effects of low protein diet with a balanced amino acid pattern on growth performance, meat quality and cecal microflora of finishing pigs

BACKGROUND

The present study aimed to investigate the effects of low protein diets balanced with four amino acids on growth performance, meat quality and cecal microflora of finishing pigs. Fifty-four healthy hybrid barrows (Duroc × Landrace × Yorkshire) with an average body weight of 70.12 ± 4.03 kg were randomly assigned to one of the three dietary treatments with six replicate pens per treatment (three barrows per pen). The three dietary treatments included a normal protein diet (NP), a low protein diet (LP) and a very low protein diet (VLP).

RESULTS

The average daily gain, average daily feed intake and feed conversion ratio of pigs were not significantly changed with the LP and VLP diets compared to the NP diet (P > 0.05). The water holding capacity and shear force of longissimus dorsi muscle were decreased, whereas the intramuscular fat content of the longissimus dorsi muscle was increased (P < 0.05) in pigs fed with the LP and VLP diets compared to the NP diet. The contents of saturated fatty acids in muscle were decreased (P < 0.05), whereas the content of polyunsaturated fatty acids in muscle was increased (P < 0.01) with the VLP diet compared to the NP diet. The contents of histamine, spermidine, spermine and tyramine of muscle were decreased with the VLP diet compared to the NP diet (P < 0.05). The relative abundance of Turicibacter, Terrisporobacter, Clostridium_sensu_stricto_1 and UCG-005 was higher (P < 0.05), whereas the relative abundance of Lactobacillus and Streptococcus was lower (P < 0.05) in pigs fed with the LP and VLP diets compared to the NP diet. Based on the correlation of cecal microbiota and cecal biogenic amine, the contents of tyramine, spermidine and histamine were negatively correlated with the abundance of Terrisporobacter (P < 0.01) and the content of histamine was positively correlated with the abundance of Lactobacillus (P < 0.01).

CONCLUSION

Balanced with four essential amino acids, the VLP diet with crude protein levels decreased by > 4% increased the intramuscular fat content, changed the fatty acid and amino acid composition of longissimus dorsi muscle and the profile of cecum microbiota, and reduced the content of cecum bioamine, with no negative effect on the growth performance of pigs. © 2022 Society of Chemical Industry.

Key circRNAs from goat: discovery, integrated regulatory network and their putative roles in the differentiation of intramuscular adipocytes

BACKGROUND

The procession of preadipocytes differentiation into mature adipocytes involves multiple cellular and signal transduction pathways. Recently. a seirces of noncoding RNAs (ncRNAs), including circular RNAs (circRNAs) were proved to play important roles in regulating differentiation of adipocytes.

RESULT

In this study, we aimed to identificate the potential circRNAs in the early and late stages of goat intramuscular adipocytes differentiation. Using bioinformatics methods to predict their biological functions and map the circRNA-miRNA interaction network. Over 104 million clean reads in goat intramuscular preadipocytes and adipocytes were mapped, of which16 circRNAs were differentially expressed (DE-circRNAs). Furthermore, we used real-time fluorescent quantitative PCR (qRT-PCR) technology to randomly detect the expression levels of 8 circRNAs among the DE-circRNAs, and our result verifies the accuracy of the RNA-seq data. From the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the DE-circRNAs, two circRNAs, circ_0005870 and circ_0000946, were found in Focal adhesion and PI3K-Akt signaling pathway. Then we draw the circRNA-miRNA interaction network and obtained the miRNAs that possibly interact with circ_0005870 and circ_0000946. Using TargetScan, miRTarBase and miR-TCDS online databases, we further obtained the mRNAs that may interact with the miRNAs, and generated the final circRNA-miRNA-mRNA interaction network. Combined with the following GO (Gene Ontology) and KEGG enrichment analysis, we obtained 5 key mRNAs related to adipocyte differentiation in our interaction network, which are FOXO3(forkhead box O3), PPP2CA (protein phosphatase 2 catalytic subunit alpha), EEIF4E (eukaryotic translation initiation factor 4), CDK6 (cyclin dependent kinase 6) and ACVR1 (activin A receptor type 1).

CONCLUSIONS

By using Illumina HiSeq and online databases, we generated the final circRNA-miRNA-mRNA interaction network that have valuable functions in adipocyte differentiation. Our work serves as a valuable genomic resource for in-depth exploration of the molecular mechanism of ncRNAs interaction network regulating adipocyte differentiation.

Long-Term Dietary Supplementation with Betaine Improves Growth Performance, Meat Quality and Intramuscular Fat Deposition in Growing-Finishing Pigs

This study was designed to investigate the effects of dietary betaine supplementation on growth performance, meat quality and muscle lipid metabolism of growing-finishing pigs. Thirty-six crossbred pigs weighing 24.68 ± 0.97 kg were randomly allotted into two treatments consisting of a basal diet supplemented with 0 or 1200 mg/kg betaine. Each treatment included six replications of three pigs per pen. Following 119 days of feeding trial, dietary betaine supplementation significantly enhanced average daily gain (ADG) (p < 0.05) and tended to improve average daily feed intake (ADFI) (p = 0.08) and decreased the feed intake to gain ratio (F/G) (p = 0.09) in pigs during 100~125 kg. Furthermore, a tendency to increase ADG (p = 0.09) and finial body weight (p = 0.09) of pigs over the whole period was observed in the betaine diet group. Betaine supplementation significantly increased a*_{45 min} and marbling and decreased b*_{24 h} and cooking loss in longissimus lumborum (p < 0.05), tended to increase intramuscular fat (IMF) content (p = 0.08), however had no significant influence on carcass characteristics (p > 0.05). Betaine supplementation influenced the lipid metabolism of pigs, evidenced by a lower serum concentration of low-density lipoprotein cholesterol (p < 0.05), an up-regulation of mRNA abundance of fatty acid synthase and acetyl-CoA carboxylase (p < 0.05), and a down-regulation of mRNA abundance of lipolysis-related genes, including the silent information regulators of transcription 1 (p = 0.08), peroxisome proliferator-activated receptorα (p < 0.05), peroxisome proliferator-activated receptor gamma coactivator-1α (p = 0.07) and carnitine palmitoyl transferase 1 (p < 0.05) in longissimus lumborum. Moreover, betaine markedly improved the expression of microRNA-181a (miR-181a) (p < 0.05) and tended to enhance miR-370 (p = 0.08). Overall, betaine supplementation at 1200 mg/kg could increase the growth performance of growing-finishing pigs. Furthermore, betaine had a trend to improve meat quality and IMF content via increasing lipogenesis and down-regulating the abundance of genes associated with lipolysis, respectively, which was associated with the regulation of miR-181a and miR-370 expression by betaine.

Differences in histomorphology and expression of key lipid regulated genes of four adipose tissues from Tibetan pigs

Tibetan pigs, an indigenous pig breed in China, have high overall fat deposition and flavorful and tasty meat. They are thus good models for studying adipogenesis. Few studies have been conducted focusing on expression of lipid regulated genes in different adipose tissues of Tibetan pigs. Therefore, we compared the difference of histomorphology and expression level of lipid regulated genes through qPCR and western blot in subcutaneous fat, perirenal fat, omental adipose tissue, and inguinal fat of Tibetan pigs. Our results showed that the area of subcutaneous adipocytes in Tibetan pigs was smaller, while the other three adipose tissues (perirenal fat, greater omentum fat, inguinal fat) had cell areas of similar size. The gene expression of FABP4, FASN, FABP3, and ME1 in subcutaneous fat was significantly higher than that in perirenal fat. Furthermore, the protein expression of FABP4 was significantly lower in subcutaneous fat than in perirenal fat (p < 0.05), and the expression of FASN was higher in greater omentum fat than in subcutaneous fat (p = 0.084). The difference in adipocyte cell size and expression of lipid-regulated genes in adipose tissues from the various parts of the pig body is likely due to the different cellular lipid metabolic processes. Specially, FABP4 and FASN may be involved in the regulation of fat deposition in different adipose tissues of Tibetan pigs.

Low-protein diets supplemented with glycine improves pig growth performance and meat quality: An untargeted metabolomic analysis

For the purpose to improve meat quality, pigs were fed a normal diet (ND), a low protein diet (LPD) and a LPD supplemented with glycine (LPDG). Chemical and metabolomic analyses showed that LPD increased IMF deposition and the activities of GPa and PK, but decreased glycogen content, the activities of CS and CcO, and the abundance of acetyl-CoA, tyrosine and its metabolites in muscle. LPDG promoted muscle fiber transition from type II to type I, increased the synthesis of multiple nonessential amino acids, and pantothenic acid in muscle, which should contributed to the improved meat quality and growth rate. This study provides some new insight into the mechanism of diet induced alteration of animal growth performance and meat quality. In addition, the study shows that dietary supplementation of glycine to LPD could be used to improved meat quality without impairment of animal growth.

The comprehensive detection of miRNA and circRNA in the regulation of intramuscular and subcutaneous adipose tissue of Laiwu pig

circRNAs, as miRNA sponges, participate in many important biological processes. However, it remains unclear whether circRNAs can regulate lipid metabolism. This study aimed to explore the competing endogenouse RNA (ceRNA) regulatory network that affects the difference between intramuscular fat (IMF) and subcutaneous fat (SCF) deposition, and to screen key circRNAs and their regulatory genes. In this experiment, we identified 265 differentially expressed circRNAs, of which 187 up-regulated circRNA and 78 down-regulated circRNA in IMF. Subsequently, we annotated the function of DEcircRNA's host genes, and found that DEcircRNA's host genes were mainly involved in GO terms (including cellular response to fatty acids, lysophosphatidic acid acyltransferase activity, R-SMAD binding, etc.) and signaling pathways (fatty acid biosynthesis, Citrate cycle, TGF- β Signal pathway) related to adipogenesis, differentiation and lipid metabolism. By constructing a circRNA-miRNA network, we screened out DEcircRNA that can competitively bind to more miRNAs as key circRNAs (circRNA_06424 and circRNA_08840). Through the functional annotation of indirect target genes and protein network analysis, we found that circRNA_06424 affects the expression of PPARD, MMP9, UBA7 and other indirect target genes by competitively binding to miRNAs such as ssc-miR-339-5p, ssc-miR-744 and ssc-miR-328, and participates in PPAR signaling pathway, Wnt signaling pathway, unsaturated fatty acid and other signaling pathways, resulting in the difference of fat deposition between IMF and SCF. This study provide a theoretical basis for further research investigating the differences of lipid metabolism in different adipose tissues, providing potential therapeutic targets for ectopic fat deposition and lipid metabolism diseases.

Effect of dietary magnolia bark extract supplementation in finishing pigs on the oxidative stability of meat

BACKGROUND

Magnolia bark extract (MBE) is a natural supplement with antioxidant, anti-inflammatory, and antimicrobial activities. Its properties suggest that the dietary supplementation in livestock could improve the quality of products. Therefore, the aim of this study was to investigate, for the first time, the effect of dietary MBE supplementation (0.33 mg/kg) in finishing pigs on the oxidative stability of meat. Oxidative stability is of paramount importance for pork, as it affects storage, retail, and consumer acceptance. For the purpose, the fatty acid profile, cholesterol, fat-soluble vitamins, antioxidant enzymes (catalase, glutathione peroxidase, and superoxide dismutase), non-enzymatic antioxidant capacity (TEAC, FRAP, and Folin-Ciocalteu assays), color stability, and lipid stability of pork were assessed.

RESULTS

Concerning carcass characteristics, dietary MBE did not affect cold carcass yield, but reduced (P = 0.040) the chilling weight loss. The meat from pigs fed MBE had a lower (P = 0.031) lightness index than the control meat. No effect on intramuscular fat, cholesterol, and fatty acid profile was observed. Dietary MBE did not affect the content of vitamin E (α-tocopherol and γ-tocopherol) in pork, whereas it reduced (P = 0.021) the retinol content. The catalase activity was 18% higher (P = 0.008) in the meat from pigs fed MBE compared with the control group. The MBE supplementation reduced (P = 0.039) by 30% the thiobarbituric acid reactive substances (TBARS) in raw pork over 6 d of aerobic refrigerated storage. Instead, no effect on lipid oxidation was observed in cooked pork. Last, the meat from pigs fed MBE reduced Fe³⁺-ascorbate catalyzed lipid oxidation in muscle homogenates, with a lower (P = 0.034) TBARS value than the control group after 60 min of incubation.

CONCLUSIONS

Dietary MBE supplementation in finishing pigs delayed the lipid oxidation in raw meat. This effect was combined with an increased catalase concentration. These results suggest that dietary MBE could have implications for improving the shelf-life of pork.

Effect of Concentration of Flaxseed (Linum usitatissimum) and Duration of Administration on Fatty Acid Profile, and Oxidative Stability of Pork Meat

Flaxseed is a common ingredient used for livestock feed. The aim of this work was to study the effect of a diet supplemented with flaxseed at 5% and 10% concentrations in the intervals of 3 and 6 weeks prior slaughter on fatty acid profile and oxidative stability of pork meat. Meat samples were collected after slaughter from each animal (five groups, n = 6). Samples of the musculus longissimus dorsi (MLD) and the musculus gluteobiceps (MGB) were selected. Chemical composition, fatty acid profile and oxidative stability during the storage of meat under chilling conditions (4 °C, 7 days) was analyzed. The addition of flaxseed significantly affected the composition of fatty acid profile and the shelf life of the produced meat. The fat content was changed in the experimental groups with 10% flaxseed supplementation (10.84% in MGB and 9.56% MLD) versus the control group. Despite the different concentrations of flaxseed, the best EPA/AA ratio was observed in the experimental groups fed with flaxseed supplementation for 3 weeks. The worst oxidative stability of meat samples (p < 0.05) was recorded in the experimental groups with the addition of flaxseed for 6 weeks, which was related to higher PUFA content in samples of the experimental groups and higher susceptibility of PUFAs to lipid oxidation. The oxidative stability of meat in the experimental group fed 5% flaxseed supplementation for 3 weeks was not affected.

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

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

Intramuscular Fat Selection in Rabbits Modifies the Fatty Acid Composition of Muscle and Liver Tissues

Simple Summary

Intramuscular fat content improves the juiciness, tenderness, and flavor of meat, but it can also affect its nutritional quality. A divergent selection experiment for intramuscular fat content was performed on rabbits for 10 generations to study the metabolism of the selected and correlated traits. The direct response to selection and the correlated responses in the meat fatty acid content, in the liver fat and its fatty acid content, and in plasma metabolic markers related to liver metabolism were studied. Increasing intramuscular fat content led to higher fat deposition in the carcass, but not in the liver. The fatty acid contents of Longissimus thoracis et lumborum muscle and liver were modified after selection, for which the microbiome composition also played an important role. A higher concentration of plasma lipids was found in the low-IMF line, probably due to a lower uptake by the muscle and adipose tissue.

Abstract

This study was conducted on two rabbit lines divergently selected for intramuscular fat (IMF) content in the Longissimus thoracis et lumborum (LTL) muscle. The aim was to estimate the direct response to selection for IMF after 10 generations, and the correlated responses in carcass quality traits, meat fatty acid content, liver fat and its fatty acid content, and in plasma metabolic markers related to liver metabolism. Selection for IMF content was successful, showing a direct response equivalent to 3.8 SD of the trait after 10 generations. The high-IMF line (H) showed a greater dissectible fat percentage than the low-IMF line (L), with a relevant difference (D_H-L = 0.63%, P_r = 1). No difference was found in liver fat content (D_H-L = −0.04, P₀ = 0.62). The fatty acid content of both LTL muscle and liver was modified after selection. The LTL muscle had greater saturated (SFA; D_H-L = 5.05, P_r = 1) and monounsaturated fatty acids (MUFA; D_H-L = 5.04, P_r = 1) contents in the H line than in the L line. No relevant difference was found in polyunsaturated fatty acids content (PUFA; P_r = 0.05); however, greater amounts of C18:2n6 (D_H-L = 3.03, P_r = 1) and C18:3n3 (D_H-L = 0.56, P_r = 1) were found in the H than in the L line. The liver presented greater MUFA (D_H-L = 1.46) and lower PUFA (D_H-L = −1.46) contents in the H than in the L line, but the difference was only relevant for MUFA (P_r = 0.86). The odd-chain saturated fatty acids C15:0 and C17:0 were more abundant in the liver of the L line than in the liver of the H line (D_H-L = −0.04, P_r = 0.98 for C15:0; D_H-L = −0.09, P_r = 0.92 for C17:0). Greater concentrations of plasma triglycerides (D_H-L = −34) and cholesterol (D_H-L = −3.85) were found in the L than in the H line, together with greater plasma concentration of bile acids (D_H-L = −2.13). Nonetheless, the difference was only relevant for triglycerides (P_r = 0.98).

Influence of Feeding Weaned Piglets with Laminaria digitata on the Quality and Nutritional Value of Meat

Laminaria digitata is a novel feedstuff that can be used in pig diets to replace conventional feedstuffs. However, its resilient cell wall can prevent the monogastric digestive system from accessing intracellular nutrients. Carbohydrate-active enzyme (CAZyme) supplementation is a putative solution for this problem, degrading the cell wall during digestion. The objective of this work was to evaluate the effect of 10% L. digitata feed inclusion and CAZyme supplementation on the meat quality and nutritional value of weaned piglets. Forty weaned piglets were randomly allocated to four experimental groups (n = 10): control, LA (10% L. digitata, replacing the control diet), LAR (LA + CAZyme (0.005% Rovabio® Excel AP)) and LAL (LA + CAZyme (0.01% alginate lyase)) and the trial lasted for two weeks. The diets had no effect on any zootechnical parameters measured (p > 0.05) and meat quality traits, except for the pH measured 24 h post-mortem, which was higher in LAL compared to LA (p = 0.016). Piglets fed with seaweed had a significantly lower n-6/n-3 PUFA ratio compared to control, to which the higher accumulation of C20:5n-3 (p = 0.001) and C18:4n-3 (p < 0.0001) contributed. In addition, meat of seaweed-fed piglets was enriched with bromine (Br, p < 0.001) and iodine (I, p < 0.001) and depicted a higher oxidative stability. This study demonstrates that the nutritional value of piglets’ meat could be improved by the dietary incorporation of L. digitata, regardless of CAZyme supplementation, without negatively affecting growth performance in the post-weaning stage.

Dietary calcium supplementation promotes the accumulation of intramuscular fat

BACKGROUND

In the livestock industry, intramuscular fat content is a key factor affecting meat quality. Many studies have shown that dietary calcium supplementation is closely related to lipid metabolism. However, few studies have examined the relationship between dietary calcium supplementation and intramuscular fat accumulation.

METHODS

Here, we used C2C12 cells, C57BL/6 mice (n = 8) and three-way cross-breeding pigs (Duroc×Landrace×Large white) (n = 10) to study the effect of calcium addition on intramuscular fat accumulation. In vitro, we used calcium chloride to adjust the calcium levels in the medium (2 mmol/L or 3 mmol/L). Then we measured various indicators. In vivo, calcium carbonate was used to regulate calcium levels in feeds (Mice: 0.5% calcium or 1.2% calcium) (Pigs: 0.9% calcium or 1.5% calcium). Then we tested the mice gastrocnemius muscle triglyceride content, pig longissimus dorsi muscle meat quality and lipidomics.

RESULTS

In vitro, calcium addition (3 mmol/L) had no significant effect on cell proliferation, but promoted the differentiation of C2C12 cells into slow-twitch fibers. Calcium supplementation increased triglyceride accumulation in C2C12 cells. Calcium addition increased the number of mitochondria and also increased the calcium level in the mitochondria and reduced the of key enzymes activity involved in β-oxidation such as acyl-coenzyme A dehydrogenase. Decreasing mitochondrial calcium level can alleviate lipid accumulation induced by calcium addition. In addition, calcium addition also reduced the glycolytic capacity and glycolytic conversion rate of C2C12 cells. In vivo, dietary calcium supplementation (1.2%) promoted the accumulation of triglycerides in the gastrocnemius muscle of mice. Dietary calcium supplementation (1.5%) had no effect on pig weight, but significantly improved the flesh color of the longissimus dorsi muscle, reduced the backfat thickness and increased intramuscular fat content in pigs. Besides, calcium addition had no effect on longissimus dorsi pH, electrical conductivity and shear force.

CONCLUSIONS

These results suggest that calcium addition promotes intramuscular fat accumulation by inhibiting the oxidation of fatty acids. These findings provide a new tool for increasing intramuscular fat content and an economical strategy for improving meat quality.

GOT1 regulates adipocyte differentiation by altering NADPH content

Objective

This study was performed to examine whether the porcine glutamic-oxaloacetic transaminase 1 (GOT1) gene has important functions in regulating adipocyte differentiation.

Methods

Porcine GOT1 knockout and overexpression vectors were constructed and transfected into the mouse adipogenic 3T3-L1 cells. Lipid droplets levels were measured after 8 days of differentiation. The mechanisms through which GOT1 participated in lipid deposition were examined by measuring the expression of malate dehydrogenase 1 (MDH1) and malic enzyme (ME1) and the cellular nicotinamide adenine dinucleotide phosphate (NADPH) content.

Results

GOT1 knockout significantly decreased lipid deposition in the 3T3-L1 cells (p< 0.01), whereas GOT1 overexpression significantly increased lipid accumulation (p<0.01). At the same time, GOT1 knockout significantly decreased the NADPH content and the expression of MDH1 and ME1 in the 3T3-L1 cells. Overexpression of GOT1 significantly increased the NADPH content and the expression of MDH1 and ME1, suggesting that GOT1 regulated adipocyte differentiation by altering the NADPH content.

Conclusion

The results preliminarily revealed the effector mechanisms of GOT1 in regulating adipose differentiation. Thus, a theoretical basis is provided for improving the quality of pork and studies on diseases associated with lipid metabolism.

Lipidomic and Transcriptomic Analysis of the Longissimus Muscle of Luchuan and Duroc Pigs

Meat is an essential food, and pork is the largest consumer meat product in China and the world. Intramuscular fat has always been the basis for people to select and judge meat products. Therefore, we selected the Duroc, a western lean pig breed, and the Luchuan, a Chinese obese pig breed, as models, and used the longissimus dorsi muscle for lipidomics testing and transcriptomics sequencing. The purpose of the study was to determine the differences in intramuscular fat between the two breeds and identify the reasons for the differences. We found that the intramuscular fat content of Luchuan pigs was significantly higher than that of Duroc pigs. The triglycerides and diglycerides related to flavor were higher in Luchuan pigs compared to Duroc pigs. This phenotype may be caused by the difference in the expression of key genes in the glycerolipid metabolism signaling pathway.

Study of meat quality and flavour in different cuts of Duroc-Bamei binary hybrid pigs

Background

Meat quality and flavour are important criteria for judging fresh pork and processed products. However, there have been few studies on meat quality and volatile flavour substances of different parts of binary hybrid pigs.

Objective

To study the differences in meat quality and volatile flavour substances between different cuts of pork, which could provide the basis for consumer decision‐making when purchasing pork.

Methods

Twenty Du‐Ba binary hybrid pigs (first filial [F1] generation) bred from Duroc and Bamei pigs were used. This study systematically compared and analysed the basic nutritional components, amino acid composition, fatty acid composition and flavour profiles of longissimus dorsi, rib muscle and tendon meat of four Du‐Ba binary hybrid pigs; all assays were repeated in triplicate.

Results

Crude protein, calcium and phosphorus content in tendon meat were higher than that in the longissimus dorsi. The intramuscular fat content of the rib muscle was higher than that in the longissimus dorsi and tendon meat (p < 0.05). The amino acid content was highest in the tendon meat. The levels of essential amino acids and flavour‐associated amino acids per kilogram of longissimus dorsi were higher than those in the rib muscle and tendon meat. Moreover, the content of aspartic acid, serine and cystine were higher in the longissimus dorsi than in the other two parts. The type of saturated fatty acids and the type and content of unsaturated fatty acids in tendon meat were higher than in the longissimus dorsi and rib muscle. The total content of volatile flavour compounds was higher in the longissimus dorsi than in the rib muscle and tendon meat.

Conclusion

The rib muscle contains high deposits of fat, and tendon meat has a relatively high nutritional value, while the longissimus dorsi has a stronger flavour.

Coculture of porcine cumulus–oocyte complexes with porcine luteal cells during IVM: effect on oocyte maturation and embryo development

Coculture with somatic cells is an alternative to improve suboptimal invitro culture conditions. In pigs, IVF is related to poor male pronuclear formation and high rates of polyspermy. The aim of this study was to assess the effect of a coculture system with porcine luteal cells (PLCs) on the IVM of porcine cumulus–oocyte complexes (COCs). Abattoir-derived ovaries were used to obtain PLCs and COCs. COCs were matured invitro in TCM-199 with or without the addition of human menopausal gonadotrophin (hMG; C+hMG and C-hMG respectively), in coculture with PLCs from passage 1 (PLC-1) and in PLC-1 conditioned medium (CM). In the coculture system, nuclear maturation rates were significantly higher than in the C-hMG and CM groups, but similar to rates in the C+hMG group. In cumulus cells, PLC-1 coculture decreased viability, early apoptosis and necrosis, and increased late apoptosis compared with C+hMG. PLC-1 coculture also decreased reactive oxygen species levels in cumulus cells. After IVF, monospermic penetration and IVF efficiency increased in the PLC-1 group compared with the C+hMG group. After invitro culture, higher blastocysts rates were observed in the PLC-1 group. This is the first report of a coculture system of COCs with PLCs. Our model could be an alternative for the conventional maturation medium plus gonadotrophins because of its lower rates of polyspermic penetration and higher blastocysts rates, key issues in porcine invitro embryo production.