This study investigated the impact of dietary tryptophan levels on carcass traits, meat quality, flavor profiles and antioxidant capacity in finishing pigs under large-scale farming conditions. Approximately 400 finishing pigs were randomly allocated to four groups, each with four replicate pens. The pigs received diets containing either the recommended level of tryptophan or an increased level of tryptophan by 15%, 35%, or 55%, for a period of 31 days. The results showed that dietary tryptophan had no significant influence on growth performance or carcass traits. While meeting the tryptophan requirements, increasing dietary tryptophan levels by 35% reduced the b* value and shear force of pork. Moreover, a 35% increase in tryptophan levels weakened the fruity, green, fatty and fresh flavor profiles, as indicated by decreased levels of key volatile flavor compounds (VOCs). These included the fruity-associated 6-methyl-5-hepten-2-one and (E,E)-3,5-octadien-2-one, the fresh and fruity-related hexanoic acid methyl ester and ethyl 2-ethylhexanoate, as well as the green and fatty odor-contributing nonanal. Notably, increasing dietary tryptophan levels increased antioxidant capacity and tryptophan metabolite content, particularly nicotinamide, which were associated with changes in key VOCs. This study deepens our understanding of how dietary tryptophan levels affect pork flavor and provides valuable insights for improving pork quality through nutritional regulation.

Pterostilbene (PTS), a more bioavailable analog of resveratrol (RES), is a promising natural metabolic regulator for improving metabolic health. The metabolic regulatory benefits of RES are believed to be associated with SIRT1 activation. However, the direct activation of SIRT1 by RES was proven to be an in vitro artifact. Here, we demonstrate that PTS is a more potent metabolic regulator than RES. More significantly, we have identified estrogen receptor α (ERα) as the intermediate signaling mediating SIRT1 expression by both RES and PTS. First, RES and PTS function as ERα agonists to stimulate Sirt1 transcription. Second, RES and PTS act as stabilizers of ERα-SIRT1 interaction, blocking ubiquitination and thereby enhancing their protein stability. Third, RES and PTS promote ERα deacetylation, subsequently increasing ERα transactivation. Finally, skeletal muscle-specific ERα knockout attenuates the metabolic regulatory benefits of PTS. Together, our study demonstrates that PTS is a more potent metabolic regulator than RES by activating the ERα/SIRT1 signaling.

Supplementation with Lactobacillus strains attracts intense interest for its potential in regulating fat accumulation in both humans and animals. However, the functional disparities among Lactobacillus strains remain poorly understood. This study examined the impact of dietary supplementation with Lactobacillus reuteri (L. reuteri) and Lactobacillus johnsonii (L. johnsonii) on lipid metabolism, carcass traits, and meat quality in heavy finishing pigs. A total of 288 finishing pigs (equal numbers of castrated barrows and gilts; initial body weight = 109.88 ± 1.58 kg) were randomly allocated to 3 dietary treatments with 6 replicate pens and 16 pigs per pen. Pigs were fed a basal diet (CON), or the basal diet supplemented with L. reuteri or L. johnsonii at a daily dose of 5 × 1010 CFU per pig, respectively, over a 42-d experimental period. The experimental results demonstrated that compared with CON, both probiotic strains significantly decreased serum levels of cortisol and pro-inflammatory factors including TNF-α, IL-1β and IL-17, while significantly elevating the levels of anti-inflammatory factor IL-4 and total antioxidant capacity (T-AOC) (P < 0.05), and reduced the concentration of saturated fatty acids in Longissimus thoracis (LT) (P = 0.014). L. johnsonii supplementation significantly reduced backfat thickness at the 10th-rib (P = 0.040) and last-rib backfat (P = 0.025), significantly increased fat-free lean index (P = 0.015), and significantly decreased adipocyte size in subcutaneous adipose tissue (P < 0.001), accompanied by the activation of the AMPK/PPARγ signaling pathway. Compared with CON, L. reuteri supplementation significantly reduced the shear force (P = 0.043) and intramuscular fat (IMF) content (P = 0.026) of LT muscle of finishing pigs and significantly increased free valine, methionine, and isoleucine concentrations in fresh meat (P < 0.05). In conclusion, the two strains of Lactobacillus exhibited distinct characteristics. Specifically, L. johnsonii primarily promoted lipid catabolism while simultaneously suppressing lipid anabolism by activating the AMPK/PPARγ signaling pathway, leading to a reduction in backfat thickness. In contrast, L. reuteri exhibited stronger focus on improving meat quality traits, such as tenderness and amino acid composition. This study offers a valuable insight into the specific application of probiotics in high-quality pork production.

BACKGROUND:L-malic acid (MA) consumption in sows during late gestation could improve glucose metabolism and increase myogenin expression in the skeletal muscle of the offspring. OBJECTIVES:This study aimed to investigate the impact of maternal MA intake during the critical period of skeletal muscle development on muscle development and metabolic traits in offspring. METHODS:At day 30 of gestation, 45 Landrace × Yorkshire sows were divided into 3 groups and received either a corn-soybean basal diet (control) or the basal diet supplemented with 1% or 2% MA complex. Sows' serum was collected at day 50 and 90 of gestation. Levels of inflammation markers and myokines were measured in piglet serum at birth and at weaning (21 day of age). The longissimus dorsi muscle was also collected to assess skeletal muscle growth and development. Statistical analyses included t-tests, 1-way or 2-way analysis of variance. RESULTS:Dietary MA supplementation reduced inflammation and oxidative stress in sows. MA increased serum insulin-like growth factor 1 by 18.51% (P < 0.01) and decreased transforming growth factor β1 concentrations by 42.77% (P < 0.01) in sows, particularly at day 50 of gestation. Notably, maternal MA reduced inflammation and altered myokine secretion. It also increased paired box 7 expression in piglet skeletal muscle by 74.29% at day 1 (P < 0.05), and induced muscle fiber-type transition at day 21. This is evidenced by increased slow myosin heavy chain protein concentrations (P < 0.05) and decreased myosin heavy chain-IIx messenger ribonucleic acid (RNA) concentrations (P < 0.05). RNA-sequential analysis revealed that maternal MA consumption affected the expression of genes involved in amino acid and fatty acid metabolism in the skeletal muscle of piglets at day 1, while inhibiting the Hippo signaling pathway. CONCLUSIONS:These findings suggest that maternal MA consumption is a potential strategy for remodeling skeletal muscle function and improving metabolic health in offspring. This porcine model will provide translational insights into maternal nutrition interventions for human skeletal muscle development.

To explore the effects of dietary lysine level (DLLs) on growth performance, carcass traits, meat quality and flavor characteristics in finishing pigs under large-scale commercial farming conditions, approximately 450 Duroc × Landrace × Yorkshire crossbred finishing pigs (initial body weight: 103.65 ± 4.28 kg) were randomly assigned to four treatment groups in this study. Each group consisted of four replicate pens, with 25~30 pigs per pen. The Lys100 group received a diet formulated according to the NRC (2012) standard. The standardized ileal digestible lysine (SID Lys) levels in the diets for the Lys115, Lys130 and Lys145 groups were set at 115%, 130% and 145% of the level in the Lys100 group, respectively. The trial lasted for 31 days. The results showed that increasing DLLs by 15%, 30% or 45%, while safeguarding the lysine requirement and maintaining the ideal ratios of other essential amino acids to lysine, had no negative impact on growth performance or meat quality. For carcass traits, increasing lysine levels in diets linearly increased loin eye area (p = 0.018) and tended to reduce backfat thickness at the 10th rib (p = 0.096). Methionine and glycine contents in the longissimus thoracis (LT) muscle linearly increased with an increase in DLLs (p = 0.014 and 0.073, respectively). Furthermore, increasing lysine levels by 45% significantly increased the percentage of volatile flavor compounds (VOCs) belonging to nitrogen compounds (p = 0.040), ethers (p = 0.026) and aldehydes (p = 0.040), as well as increased contents of key VOCs, such as (E)-2-Nonenal (p = 0.005), (E)-2-Octenal (p = 0.005) and 1-Octen-3-one (p = 0.008), contributing to enhanced sweet, fruity, fatty and waxy flavor profiles. According to various indexes, better carcass traits and pork flavor could be achieved by increasing lysine levels by 45% in diets based on the recommended value for finishing pigs.

BACKGROUND:Skeletal muscle is essential for exercise and maintaining metabolic homeostasis. Myo-inositol (INS), the main isomer of inositol, has been shown to enhance glucose metabolism and skeletal muscle growth in fish. However, its effect on skeletal muscle development in mammals remains unclear. OBJECTIVES:This research seeks to investigate the positive impacts of maternal INS intake during gestation on skeletal muscle development in the offspring using pig models. METHODS:Random allocation was performed to distribute 45 parity-matched Landrace × Yorkshire sows across 3 treatment arms: control, 0.15% INS, and 0.3% INS supplementation groups from D30 of pregnancy until farrowing. The levels of inflammation and oxidative stress in the serum (n = 8) and the composition of the gut microbiota (n = 6) of pregnant sows were evaluated. On postnatal day 1, 6 male piglets (n = 6) were selected from each of 6 litters in the control group and the 0.3% INS group. The mRNA and protein levels of key genes involved in skeletal muscle development and fiber-type composition were measured. RNA-seq analysis was then performed using the skeletal muscle of piglets. Data were analyzed using 1-way analysis of variance followed by Tukey's multiple comparison test or an unpaired 2-tailed Student's t-test. RESULTS:Dietary INS supplementation reduced inflammatory markers on D50 of pregnancy, alleviated oxidative stress in sows, and decreased the number of piglets with low birth weight by ∼60% (P = 0.01). On D50 of pregnancy, dietary supplementation with 0.3% INS reduced the relative abundance of Firmicutes from 72.92% to 60.17%, while increasing the abundance of beneficial fecal microbes in sows, such as Bacteroidetes, Fibrobacterota, Unclassified_f_Lachnospiraceae, and Prevotellaceae_NK3B31_group. Notably, maternal 0.3% INS intake increased paired box 7 protein level by 88.90% (P = 0.05) and induced muscle-fiber type transition from glycolytic to oxidative fibers in the skeletal muscle of piglets at postnatal day 1. This was evidenced by a 50.95% increase in the mRNA level of myosin heavy chain (MyHC) Ⅱa (P < 0.05) and a 55.50% decrease in the protein level of fast MyHC (P < 0.01). Transcriptomic analysis further revealed that maternal intake of 0.3% INS regulated signaling pathways associated with skeletal muscle development, such as mitogen-activated protein kinase, Notch, and Wnt. CONCLUSIONS:INS intake was beneficial for the inflammatory and oxidative status of pregnant sows and further improved skeletal muscle development characteristics in the offspring.

This study aimed to investigate the effects of dietary valine/isoleucine (V/I) ratio and slaughter weight on the profile of pork flavor precursors. Metabolomics and volatilomic profiling were performed on meat harvested from a 2 × 2 factorial feeding study. Thirty-six Duroc × Landrace × Yorkshire castrated male pigs with around 75 kg body weight (BW) were randomly allocated to two dietary treatments, involving V/I (1.23 and 2.60 at 75 to 100 kg BW, 1.24 and 2.39 at 100 to 135 kg BW for the normal dietary valine/isoleucine ratio defined N [V/I] and high dietary valine/isoleucine ratio defined H [V/I], respectively) and two slaughter weights (lower weight [LW] 100 kg and higher weight [HW] 130 kg). Each group consisted of six replicates of three pigs per replicate. The trial lasted for 63 d. Dietary V/I significantly affected several metabolic pathways in muscle, including alanine, aspartate and glutamate metabolism, fructose and mannose metabolism, and amino sugar and nucleotide sugar metabolism. On the other hand, contents of acylcarnitine (ACar; P < 0.001) and lysophosphatidylethanolamine (LPE; P = 0.036) were significantly higher in the meat of the HW pigs than those of the LW pigs. Among 48 volatile organic compounds (VOCs) identified in pork, the concentrations of seven VOCs were altered by dietary V/I, that of 17 VOCs by slaughter weight, and acetoin and 1-heptanol by both factors (P < 0.05). In addition, increased dietary V/I altered 53 hydrophilic compounds and 10 VOCs in LW pigs, and altered 39 hydrophilic compounds and six VOCs in HW pigs (P < 0.05). In conclusion, the increased dietary V/I significantly altered flavor precursors of pork, but this effect decreased as the slaughter weight increased.

Background A deterioration in the meat quality of broilers has attracted much more attention in recent years. L-malic acid (MA) is evidenced to decrease meat drip loss in broilers, but the underlying molecular mechanisms are still unclear. It’s also not sure whether the outputs obtained under experimental conditions can be obtained in a commercial condition. Here, we investigated the effects and mechanisms of dietary MA supplementation on chicken meat drip loss at large-scale rearing. Results Results showed that the growth performance and drip loss were improved by MA supplementation. Meat metabolome revealed that L-2-aminoadipic acid, β-aminoisobutyric acid, eicosapentaenoic acid, and nicotinamide, as well as amino acid metabolism pathways connected to the improvements of meat quality by MA addition. The transcriptome analysis further indicated that the effect of MA on drip loss was also related to the proper immune response, evidenced by the enhanced B cell receptor signaling pathway, NF-κB signaling pathway, TNF signaling pathway, and IL-17 signaling pathway. Conclusions We provided evidence that MA decreased chicken meat drip loss under commercial conditions. Metabolome and transcriptome revealed a comprehensive understanding of the underlying mechanisms. Together, MA could be used as a promising dietary supplement for enhancing the water-holding capacity of chicken meat.

Laminarin mainly consists of fucoidan, a unique, naturally active sulfate polysaccharide. Laminarin is known for its outstanding multiple bioactives, but its role in lactation remains largely unknown. Therefore, this study aimed to explore the influence of maternal intake of laminarin on lactation and infant health in a porcine model. A total of 20 sows of parity 6.85 ± 0.88 with similar comprehensive scores were randomly allocated to two dietary treatments to receive a basal diet with/without supplementary laminarin. We showed that maternal intake of laminarin improved the antioxidant capacity and intestinal barrier function of the offspring, alleviated the inflammatory response, and facilitated infant growth and health. Mechanistically, maternal consumption of laminarin significantly modified the metabolite profiles of colostrum and milk. We also demonstrated in a vitro study that coniferyl aldehyde, a representative differential milk metabolite, enhanced antioxidant capacity and tight junction protein expression levels in intestinal epithelial cells. In summary, maternal intake of laminarin facilitated offspring health and growth by fortifying milk metabolites.

Pork is an affordable protein source with higher nutrient density. In recent years, meat quality in pigs is getting increasing attention, which has a direct impact on the economic value of pork. Dietary amino acids play a key role in pig production, not only regulating pig growth and health, but also contributing significantly to meat quality. In this review, we discuss the effect of skeletal muscle composition on meat quality. Importantly, we summarize the levels of essential amino acids (EAAs), such as lysine, methionine, threonine, tryptophan and branched-chain amino acids (BCAAs), in diets for finishing pigs to improve meat quality. The beneficial effects of flavor amino acids on meat quality, including flavor production, muscle fiber-type composition and intramuscular fat deposition, are further systematically summarized. We also focus on the impact of dietary amino acid levels on environmental benefits, although research in this area is still limited. Considering that the previously established EAA requirements are based on the principle of maximizing growth rate and feed conversion, this review will provide new insights into the effects of dietary amino acids on aspects of meat quality and highlight the current gaps to promote future research.

Background Excessive backfat deposition lowering carcass grade is a major concern in the pig industry, especially in most breeds of obese type pigs. The mechanisms involved in adipogenesis and fat accumulation in pigs remain unclear. Lysine 2-hydroxyisobutyrylation (Khib), is a novel protein post-translational modification (PTM), which play an important role in transcription, energy metabolism and metastasis of cancer cells, but its role in adipogenesis and fat accumulation has not been shown. Results In this study, we first analyzed the modification levels of acetylation (Kac), Khib, crotonylation (Kcr) and succinylation (Ksu) of fibro-adipogenic progenitors (FAPs), myogenic precursors (Myo) and mesenchymal stem cells (MSCs) with varied differentiation potential, and found that only Khib modification in FAPs was significantly higher than that in MSCs. Consistently, in parallel with its regulatory enzymes lysine acetyltransferase 5 (KAT5) and histone deacetylase 2 (HDAC2) protein levels, the Khib levels increased quadratically (P < 0.01) during adipogenic differentiation of FAPs. KAT5 knockdown in FAPs inhibited adipogenic differentiation, while HDAC2 knockdown enhanced adipogenic differentiation. We also demonstrated that Khib modification favored to adipogenic differentiation and fat accumulation by comparing Khib levels in FAPs and backfat tissues both derived from obese-type pigs (Laiwu pigs) and lean-type pigs (Duroc pigs), respectively. Accordingly, the expression patterns of KAT5 and HDAC2 matched well to the degree of backfat accumulation in obese- and lean-type pigs. Conclusions From the perspective of protein translational modification, we are the first to reveal the role of Khib in adipogenesis and fat deposition in pigs, and provided new clues for the improvement of fat accumulation and distribution as expected via genetic selection and nutritional strategy in obese-type pigs.

Myoblast differentiation plays a vital role in skeletal muscle regeneration. However, the protein-coding genes controlling this process remain incompletely understood. Here, we showed that chloride intracellular channel 5 (CLIC5) exerts a critical role in mediating myogenesis and skeletal muscle regeneration. Deletion of CLIC5 in skeletal muscle leads to reduced muscle weight and decreases the number and differentiation potential of satellite cells. In vitro, CLIC5 consistently inhibits myoblast proliferation while promoting myotube formation. CLIC5 promotes myogenic differentiation by activating the canonical Wnt/β-catenin signaling pathway in a biglycan (BGN)-dependent manner. CLIC5 deletion impairs muscle regeneration. Paired box gene 7 (Pax7) expression and the activity of BGN-mediated canonical Wnt/β-catenin signaling are reduced in CLIC5-deficient mice. Conversely, increasing CLIC5 levels in skeletal muscles enhances muscle regeneration capacity. In conclusion, our findings underscore CLIC5 as a pivotal regulator of myogenesis and skeletal muscle regeneration, functioning through interaction with BGN to activate the canonical Wnt/β-catenin signaling pathway.

Fetus loss in early pregnancy is of major concern to both humans and animals, and this issue is largely influenced by embryo implantation. Chenodeoxycholic acid (CDCA), a primary bile acid, contributes to metabolic improvements and protects against intrahepatic cholestasis of pregnancy. However, the effect of CDCA on embryo implantation during early pregnancy has not been investigated. The present study demonstrated that CDCA administration during early pregnancy improved embryo implantation in sows and rats, thereby improving the pregnancy outcomes of sows. CDCA significantly reduced inflammation, oxidative stress, and insulin resistance. The metabolomics analysis indicated significant differences in the fecal metabolome, especially regarding the level of secondary bile acids, between the control and CDCA-treated sows. CDCA also influenced the serum metabolite profiles in sows, and the serum L-Histidine level was significantly correlated with the abundance of 19 differential fecal metabolites. Importantly, L-Histidine administration improved embryo implantation and metabolic health in rats during early pregnancy. Moreover, CDCA administration during early pregnancy also led to long-term metabolic improvements in sows. Our data indicated that CDCA improved embryo implantation by alleviating inflammation and oxidative stress, improving insulin sensitivity, and modulating the interaction between the gut microbiota and host metabolites. Therefore, CDCA intervention is a potential therapeutic strategy regarding embryo loss during pregnancy.

In this study, we explored the role of protein transcriptional modification (PTM) in the adipogenesis and fat accumulation of intramuscular adipocytes. Intramuscular fat (IMF) is mainly stored in adipocytes interspersed in the perimysial space or within fascicles, and its content is a key factor attributing to meat quality in farm animals, especially in terms of tenderness, flavor and juiciness. The early stage from the fetus to the neonate is crucial for skeletal muscle development involving myogenesis, adipogenesis, and fibrogenesis, and is susceptible to environmental factors. Previous studies have been subjected to explore the molecular mechanism involved in IMF development. However, it was obscured by muscular background of IMF adipocytes. Therefore, we investigated PTM dynamics from three aspects: 1) first analyzed PTM levels of lysine acetylation (Kac), 2-hydroxyisobutyrylation (Khib), crotonylation (Kcr) and succinylation (Ksu) in three distinct differentiation potenctial primary stem cells, including myogenic precursor cells (MPCs), fibro-adipogenic progenitors (FAPs) and MSCs isolated from neonatal longissimus dorsi muscle of pigs within 3-d of age; 2) Comparing the Khib levels of proliferative and differentiated FAPs; and 3) Exploring the role of Khib modification in the adipose tissue of obese- and lean-types of pigs. We found that only Khib level in FAPs was significantly greater than MSCs. During adipogenic differentiation of FAPs, the modification level of Khib was significantly increased quadratically in parallel with protein levels of acylation regulatory enzymes KAT5 (writer) and HDAC2 (Eraser). In comparison of Khib levels in FAPs in proliferation and in differentiation and Khib levels in backfat tissues from obese pigs (Laiwu pigs) and lean pigs (Duroc pigs), we also demonstrated that Khib modification level was positive correlated with adipogenic differentiation and fat accumulation. Accordingly, the expression patterns of KAT5 and HDAC2 were parallel to the degree of lipid accumulation in the backfat adipose tissue of finishing pigs. Furthermore, we showed that KAT5 knockdown in FAPs inhibited adipogenic differentiation, while HDAC2 knockdown enhanced adipogenic differentiation of FAPs. By employing C3H10T1/2 cells, we identified EON1 involved in Khib modification in regulation of adipo gesis and fat accumulation with analysis of Liquid chromatography-tandem mass spectrometry (LC-MS/MS) using the Tandem Mass Tag (TMT Through conditional loss- and gain-of-function mutations, we further demonstrated that khib modification of ENO1 is necessary for preadipocyte differentiation and subsequent fat accumulation by mediating cellular glycolysis. In conclusion, we are the first to reveal the role of Khib modification in adipogenesis and fat deposition in pigs, and provided new clues for the improvement of fat accumulation and distribution via genetic selection and nutritional strategy in pigs.

Intramuscular fat (IMF) content influences various meat quality traits, including tenderness, flavor, juiciness and nutritional value. This study aimed to investigate the effects of dietary inositol supplementation on meat quality, metabolic profiles, and gut microbiota composition of finishing pigs. A total of 144 finishing pigs (initial body weight 70.41 ± 0.78 kg) were randomly divided into control, 0.075%, 0.15%, and 0.3% inositol groups. The data showed that inositol increased backfat thickness at the 6th to 7th rib and 10th rib, IMF content, and improved tenderness (P ≤ 0.05, n = 8). Paralleling an increase in fat deposition, 0.3% inositol also increased the protein level of PPARγ in the subcutaneous fat (P ≤ 0.05) and longissimus thoracis (LT) muscle (P = 0.062). Inositol elevated the content of amino acids in LT muscle and enhanced amino acid metabolism of finishing pigs, including lysine degradation, tyrosine metabolism, and arginine and proline metabolism. The 16S ribosomal RNA (rRNA) sequencing showed that 0.3% inositol supplementation altered the profiles of microbes in the colon, particularly decreasing the abundance of Firmicutes (P < 0.01) and increasing the abundance of Bacteroidota (P ≤ 0.05). Correlation analysis showed that differential microbes had strong correlation with differential metabolites in serum, including amino acids. In conclusion, this study demonstrated that dietary inositol supplementation could effectively improve IMF content and tenderness of pork, enhance amino acid metabolism, and regulate gut microbiota composition of finishing pigs.

The world is facing a global nutrition crisis, as evidenced by the rising incidence of metabolic disorders such as obesity, insulin resistance and chronic inflammation. Skeletal muscle is the largest tissue in humans and plays an important role in movement and host metabolism. Muscle fibre formation occurs mainly during the embryonic stage. Therefore, maternal lifestyle, especially nutrition and exercise during pregnancy, has a critical influence on foetal skeletal muscle development and the subsequent metabolic health of the offspring. In this review, the influence of maternal obesity, malnutrition and micronutrient intake on foetal skeletal muscle development is systematically summarized. We also aim to describe how maternal exercise shapes foetal muscle development and metabolic health in the offspring. The role of maternal gut microbiota and its metabolites on foetal muscle development is further discussed, although this field is still in its 'infancy'. This review will provide new insights to reduce the global crisis of metabolic disorders and highlight current gaps to promote further research.

Skeletal muscle comprises a large, heterogeneous assortment of cell populations that interact to maintain muscle homeostasis, but little is known about the mechanism that controls myogenic development in response to artificial selection. Different pig (Sus scrofa) breeds exhibit distinct muscle phenotypes resulting from domestication and selective breeding. Using unbiased single-cell transcriptomic sequencing analysis (scRNA-seq), the impact of artificial selection on cell profiles is investigated in neonatal skeletal muscle of pigs. This work provides panoramic muscle-resident cell profiles and identifies novel and breed-specific cells, mapping them on pseudotime trajectories. Artificial selection has elicited significant changes in muscle-resident cell profiles, while conserving signs of generational environmental challenges. These results suggest that fibro-adipogenic progenitors serve as a cellular interaction hub and that specific transcription factors identified here may serve as candidate target regulons for the pursuit of a specific muscle phenotype. Furthermore, a cross-species comparison of humans, mice, and pigs illustrates the conservation and divergence of mammalian muscle ontology. The findings of this study reveal shifts in cellular heterogeneity, novel cell subpopulations, and their interactions that may greatly facilitate the understanding of the mechanism underlying divergent muscle phenotypes arising from artificial selection.

Background Maternal nutrition is essential in keeping a highly efficient production system in the pig industry. Laminarin has been shown to improve antioxidant capacity, reduce the inflammatory response, and favor the homeostasis of intestinal microbiota. However, the effect of dietary supplementation of laminarin on the reproductive performance of sows and the growth of suckling offspring remains unknown. Methods A total of 40 Landrace × Yorkshire multiparous sows on d 85 of gestation, similar in age, body weight (BW), parity and reproductive performance, were randomly divided into four dietary treatments with 10 sows per treatment, receiving a control diet (basal pregnancy or lactating diets) and a basal diet supplemented with 0.025%, 0.05% and 0.10% laminarin, respectively. The experiment lasted from d 85 of gestation to d 21 of lactation. Results Laminarin supplementation linearly increased number born alive per litter ( P = 0.03), average daily feed intake (ADFI, P < 0.01), and total milk yield of sows during the lactation of 1–21 d ( P = 0.02). Furthermore, maternal laminarin supplementation increased the average daily gain (ADG) of piglets while tending to reduce the culling and death rate before weaning. In addition, alterations to the composition of colostrum and milk, as well as to serum inflammatory cytokines and immunoglobulins of sows were observed. The fecal microbiota profile of sows supported the improvement of reproductive performance in sows and the growth performance in suckling offspring. Conclusions Dietary supplementation of laminarin during late pregnancy and lactation could significantly improve reproductive performance of sows and growth performance of piglets. Graphical Abstract

The quality of pork determines consumers' purchase intention, which directly affects the economic value of pork. Minimizing the proportion of inferior pork and producing high quality pork are the ultimate goals of the pig industry. Muscle energy metabolism, serving as a regulative hub in organism energy expenditure and storage as a fat deposit, is compatible with myofiber type composition, affecting meat color, intramuscular fat content, tenderness, pH values and drip loss. Increasing data illustrate that dietary nutrients and bioactive ingredients affect muscle energy metabolism, white adipose browning and fat distribution, and myofiber type composition in humans, and rodents. Recently, some studies have shown that modulating muscle energy metabolism and lipid accumulation through nutritional approaches could effectively improve meat quality. This article reviews the progress and development in this field, and specifically discusses the impacts of dietary supply of amino acids, lipids, and gut microbiota as well as maternal nutrition on skeletal muscle energy metabolism, lipid accumulation and meat quality of pigs, so as to provide comprehensive overview with respect to effective avenues for improving meat quality.

The normal function of skeletal muscle and adipose tissue ensures whole-body glucose homeostasis. Ca 2+ release channel inositol 1,4,5-trisphosphate receptor 1 (IP3R1) plays a vital role in regulating diet-induced obesity and disorders, but its functions in peripheral tissue regulating glucose homeostasis remain unexplored. In this study, mice with Ip3r1 specific knockout in skeletal muscle or adipocytes were used for investigating the mediatory role of IP3R1 on whole-body glucose homeostasis under normal or high-fat diet. We reported that IP3R1 expression levels were increased in the white adipose tissue and skeletal muscle of diet-induced obese mice. Ip3r1 knockout in skeletal muscle improved glucose tolerance and insulin sensitivity of mice on a normal chow diet, but worsened insulin resistance in diet-induced obese mice. These changes were associated with the reduced muscle weight and compromised Akt signaling activation. Importantly, Ip3r1 deletion in adipocytes protected mice from diet-induced obesity and glucose intolerance, mainly due to the enhanced lipolysis and AMPK signaling pathway in the visceral fat. In conclusion, our study demonstrates that IP3R1 in skeletal muscle and adipocytes exerts divergent effects on systemic glucose homeostasis, and characterizes adipocyte IP3R1 as a promising target for treating obesity and type 2 diabetes.