Increased Intramuscular Fat Content Research Articles

Mulberry Leaf Dietary Supplementation Can Improve the Lipo-Nutritional Quality of Pork and Regulate Gut Microbiota in Pigs: A Comprehensive Multi-Omics Analysis.

Mulberry leaves, a common traditional Chinese medicine, represent a potential nutritional strategy to improve the fat profile, also known as the lipo-nutrition, of pork. However, the effects of mulberry leaves on pork lipo-nutrition and the microorganisms and metabolites in the porcine gut remain unclear. In this study, multi-omics analysis was employed in a Yuxi black pig animal model to explore the possible regulatory mechanism of mulberry leaves on pork quality. Sixty Yuxi black pigs were divided into two groups: the control group (n = 15) was fed a standard diet, and the experimental group (n = 45) was fed a diet supplemented with 8% mulberry leaves. Experiments were performed in three replicates (n = 15 per replicate); the two diets were ensured to be nutritionally balanced, and the feeding period was 120 days. The results showed that pigs receiving the diet supplemented with mulberry leaves had significantly reduced backfat thickness (p < 0.05) and increased intramuscular fat (IMF) content (p < 0.05) compared with pigs receiving the standard diet. Lipidomics analysis showed that mulberry leaves improved the lipid profile composition and increased the proportion of triglycerides (TGs). Interestingly, the IMF content was positively correlated with acyl C18:2 and negatively correlated with C18:1 of differential TGs. In addition, the cecal microbiological analysis showed that mulberry leaves could increase the abundance of bacteria such as UCG-005, Muribaculaceae_norank, Prevotellaceae_NK3B31_group, and Limosilactobacillus. Simultaneously, the relative levels of L-tyrosine-ethyl ester, oleic acid methyl ester, 21-deoxycortisol, N-acetyldihydrosphingosine, and mulberrin were increased. Furthermore, we found that mulberry leaf supplementation significantly increased the mRNA expression of lipoprotein lipase, fatty acid-binding protein 4, and peroxisome proliferators-activated receptor γ in muscle (p < 0.01). Mulberry leaf supplementation significantly increased the mRNA expression of diacylglycerol acyltransferase 1 (p < 0.05) while significantly decreasing the expression of acetyl CoA carboxylase in backfat (p < 0.05). Furthermore, mulberry leaf supplementation significantly upregulated the mRNA expression of hormone-sensitive triglyceride lipase and peroxisome proliferator-activated receptor α (p < 0.05) in backfat. In addition, mulberry leaf supplementation led to increased serum leptin and adiponectin (p < 0.01). Collectively, this omic profile is consistent with an increased ratio of IMF to backfat in the pig model.

Potential of different strategies to increase intramuscular fat deposition in sheep: A meta-analysis study

We evaluated the potential of different strategies to increase intramuscular fat (IMF) deposition in sheep meat through meta-analytical methods. Additionally, this study aimed to investigate the interrelationship among diet composition, performance, carcass traits, meat quality, marbling score and IMF in sheep. The dataset was composed by 102 peer-reviewed publications. The strategies to increase IMF deposition in sheep meat were evaluated by examining the weighted mean difference (WMD) between control treatment and increased-IMF treatment (beta-agonist; glycerin; essential oil; vitamin E; lipids; tannins; feeding system and sex class). The interplay between factors such as dietary composition, performance, carcass and meat quality traits highlights how the intensification of production systems, characterized by a high grain content in the diet and shorter finishing periods, reduces IMF content of meat. The IMF content was greater in females (WMD = 0.52%; P<.0001) and castrated males (WMD = 0.53%; P = 0.001) compared to intact males. Lambs finished in feedlots exhibited a 19.23% higher IMF content (WMD = 0.74%; P <.0001) compared to those finished in pasture systems. The inclusion of lipids sources to the diets increased in IMF content (WMD = 0.11%; P = 0.008), while tannins sources decrease in IMF (WMD = −0.07%; P = 0.029). Marbling score did not prove to be an adequate indicator of IMF deposition in sheep meat, potentially due to biases in subjective marbling assessments. In conclusion, our findings suggest that the most effective strategy for enhancing IMF in lambs involves utilizing female or castrated males rather than intact males followed by finishing lambs on high concentrate diets in a feedlot. Genetics did not impact IMF in the evaluated studies while other dietary strategies to alter IMF deposition had mixed effects on IMF deposition. Tannin marginally decreased IMF, vitamin E had no effect, and lipid supplementation had varied effects on IMF deposition depending on the lipid source.

Activation of skeletal ChREBP-mediated de novo lipogenesis increases intramuscular fat content in chickens

The intracellular lipids in muscle cells of farm animals play a crucial role in determining the overall intramuscular fat (IMF) content, which has a positive impact on meat quality. However, the mechanisms underlying the deposition of lipids in muscle cells of farm animals are not yet fully understood. The purpose of this study was to determine the roles of carbohydrate-response element binding protein (ChREBP) and fructose in IMF deposition of chickens. For virus-mediated ChREBP overexpression in tibialis anterior (TA) muscle of chickens, seven 5-d-old male yellow-feather chickens were used. At 10 d after virus injection, the chickens were slaughtered to obtain TA muscles for analysis. For fructose administration trial, sixty 9-wk-old male yellow-feather chickens were randomly divided into 2 groups, with 6 replicates per group and 5 chickens per replicate. The chickens were fed either a basal diet or a basal diet supplemented with 10% fructose (purity ≥ 99%). At 4 wk later, the chickens were slaughtered, and breast and thigh muscles were collected for analysis. The results showed that the skeletal ChREBP mRNA levels were positively associated with IMF content in multiple species, including the chickens, pigs, and mice (P < 0.05). ChREBP overexpression increased lipid accumulation in both muscle cells in vitro and the TA muscles of mice and chickens in vivo (P < 0.05), by activation of the de novo lipogenesis (DNL) pathway. Moreover, activation of ChREBP by dietary fructose administration also resulted in increased IMF content in mice and notably chickens (P < 0.05). Furthermore, the lipidomics analysis revealed that ChREBP activation altered the lipid composition of chicken IMF and tented to improve the flavor profile of the meat. In conclusion, this study found that ChREBP plays a pivotal role in mediating the deposition of fat in chicken muscles in response to fructose-rich diets, which provides a novel strategy for improving meat quality in the livestock industry.

Effects of lactic acid bacteria on protein metabolism of Sunit lamb

To investigate the effect of adding lactic acid bacteria (LAB) to Sunit lambs’ diet on their protein metabolism, 18 3-month-old Sunit sheep were randomly divided into two groups (Group C (non-feeding of LAB) and Group L (feeding of LAB)) for a 90 d feeding trial. After the animals were slaughtered, we measured several key factors, including basal indices, amino acid composition, protein metabolism enzyme activity, and protein metabolism-related gene expression. There were nine replications of each group. The data show that LAB had a significant effect on the intramuscular fat (IMF) content (P<0.001). The composition of amino acids in the serum and mutton was improved by the addition of LAB. The addition of LAB led to a significant increase in the expression of genes related to AKT serine/threonine kinase 1 (Akt1), mammalian target of rapamycin (mTOR), p70 ribosomal protein S6 kinase (p70S6K1), and eukaryotic initiation factor 4E (eIF4E) protein synthesis (P<0.05), while the expression of all genes related to protein catabolism was reduced. Thus, dietary LAB can increase IMF content, improve amino acid composition, regulate protein metabolism in lambs, and provide a new way and theoretical basis for dietary management to improve meat quality in housed sheep.

Effects of dietary standardized ileal digestible lysine to net energy ratio and wheat level on growth performance, meat quality, intestinal microbiota and body metabolism of finishing pigs

Lowing lysine (Lys): energy ratio based on corn-soybean diets could increase intramuscular fat (IMF) content, the effectiveness of it in enhancing IMF content when corn is partially substituted by wheat is unclear. This study aimed to determine the effects of dietary wheat levels and standardized ileal digestible (SID) Lys: net energy (NE) ratio on growth performance and meat quality, alteration in gut microbiota and body metabolism, as well as its correlation with meat quality are revealed via combined microbiome and metabolomic methods. A total of 72 pigs were randomly divided into four groups and fed with high SID Lys:NE ratio (HR) diets containing 25% wheat (W25HR), low SID Lys:NE ratio (LR) diets containing 25% wheat (W25LR), HR diets containing 55% wheat (W55HR) or LR diets containing 55% wheat (W55LR). Increasing dietary wheat level impaired feed utilization during 65–90 kg phase (P < 0.05) and enhanced meat color values (P < 0.05) of longissimus dorsi (LD) in finishing pigs. Enhancing dietary wheat level decreased relative abundance of Lactobacillus and Coprococcus (P < 0.05), and inhibited microbial carbohydrate metabolism capacity (P < 0.05) in colon of finishing pigs. Changes in microbial composition and carbohydrate metabolism capacity caused by wheat level led to alteration in meat color. LR diets improved feed utilization (P < 0.05), affected amino acid and lipid metabolism, and increased IMF content in LD (P < 0.05). Reducing SID Lys:NE ratio changed the concentrations of PA, delta-tocopherol, L-arginine, AzA, BA, and L-carnitine at the 25% wheat level and ARA, SDA, Glu, fructose-6-phosphate, and isorhamnetin at the 55% wheat level in the serum (P < 0.05, VIP > 1), which could serve as key biomarkers for predicting meat quality. LR diets upregulated mRNA expression levels of CCAAT/enhancer binding protein (C/EBP) α (P < 0.05), C/EBPβ (P < 0.01), sterol regulatory element-binding transcription factor 1c, fatty acid synthase (FAS) (P < 0.05), while downregulated mRNA abundance of adipose triglyceride lipase (ATGL) (P < 0.05) in liver at the 25% wheat level. The mRNA expression levels of C/EBPβ (P < 0.01), FAS, acetyl-coA carboxylase and fatty acid binding protein 1 (P < 0.05) were higher in the W55LR than W55HR groups, whereas mRNA abundance of ATGL was lower (P < 0.05). These results indicated that lowering SID Lys:NE ratio promoted lipogenesis, inhibited lipolysis and improved IMF deposition in LD via altering serum metabolism in different manner at two wheat level. LR diets containing 25% wheat was recommended to enhance the growth performance of finishing pigs, while concurrently achieving higher IMF content and improved meat color in the LD.

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.

Conjugated linoleic acid regulates adipocyte fatty acid binding protein expression via peroxisome proliferator-activated receptor α signaling pathway and increases intramuscular fat content.

Intramuscular fat (IMF) is correlated positively with meat tenderness, juiciness and taste that affected sensory meat quality. Conjugated linoleic acid (CLA) has been extensively researched to increase IMF content in animals, however, the regulatory mechanism remains unclear. Adipocyte fatty acid binding protein (A-FABP) gene has been proposed as candidates for IMF accretion. The purpose of this study is to explore the molecular regulatory pathways of CLA on intramuscular fat deposition. Here, our results by cell lines indicated that CLA treatment promoted the expression of A-FABP through activated the transcription factor of peroxisome proliferator-activated receptor α (PPARα). Moreover, in an animal model, we discovered that dietary supplemental with CLA significantly enhanced IMF deposition by up-regulating the mRNA and protein expression of PPARα and A-FABP in the muscle tissues of mice. In addition, our current study also demonstrated that dietary CLA increased mRNA expression of genes and enzymes involved in fatty acid synthesis and lipid metabolism the muscle tissues of mice. These findings suggest that CLA mainly increases the expression of A-FABP through PPARα signaling pathway and regulates the expression of genes and enzymes related to IMF deposition, thus increasing IMF content. These results contribute to better understanding the molecular mechanism of IMF accretion in animals for the improvement of meat quality.

SLC16A7 Promotes Triglyceride Deposition by De Novo Lipogenesis in Chicken Muscle Tissue

Triglyceride (TG) content in chicken muscle tissue signifies intramuscular fat (IMF) content, which is important for improving meat quality. However, the genetic basis of TG deposition in chicken is still unclear. Using 520 chickens from an artificially selected line with significantly increased IMF content and a control line, a genome-wide association study (GWAS) with TG content reports a region of 802 Kb located in chromosome 1. The XP-EHH and gene expression analysis together reveal that the solute carrier family 16 member A7 (SLC16A7) gene is the key candidate gene associated with TG content in chicken muscle tissue. Furthermore, the weighted gene co-expression network analysis (WGCNA) confirmed the regulatory effects of SLC16A7 on promoting TG deposition by de novo lipogenesis (DNL). Functional verification of SLC16A7 in vitro also supports this view, and reveals that this effect mainly occurs in myocytes. Our data highlight a potential IMF deposition pathway by DNL, induced by SLC16A7 in chicken myocytes. These findings will improve the understanding of IMF regulation in chicken and guide the formulation of breeding strategies for high-quality chicken.

Polymorphism of coupled indels in porcine TNNC2 alters its transcript splicing and is associated with meat quality traits.

The TNNC2 gene encodes the fast-skeletal C subunit of the troponin complex that plays a vital role in the regulation of striated muscle contraction and could be a candidate gene for pork quality. Here, we identified coupled insertion/deletion (indel) variants, a 17-bp insertion and an 11-bp deletion, in porcine TNNC2. The coupled indel variants provide an alternative splicing donor site and cause a 42-bp truncation in the first exon of TNNC2-201, leading to increased expression of TNNC2-201. Polymorphism of the two indel variants is associated with the average backfat thickness (p=3.16×10-3 ), pH value 24h post-slaughter (p=4.31×10-4 ), intramuscular fat (IMF) content (p=1.54×10-2 ), and myofiber cross-sectional area (p=2.86×10-2 ) of longissimus dorsi in a population of 425 Duroc (♂)×Luchuan (♀) pigs. In an independent population of 1,304 commercial hybrid pigs, we further confirmed that it is associated with the IMF content (p=1.75×10-4 ), pH value 45min post-slaughter (p=6.34×10-3 ), and drip loss (p=2.88×10-2 ) of the longissimus dorsi muscle. An increased frequency of the mutant allele is linked to increased IMF content, smaller myofibers, and a relatively moderate pH value. Furthermore, we detected a mutant allele frequency of 96.67% in Luchuan pigs and 86.67% in Tongcheng pigs, whereas the frequency was 0.91% in Duroc pigs, 2.04% in Landrace pigs, and 0% in Yorkshire and Pietrain pigs, indicating its opposing distributions in lean-type and Chinese local pig breeds. The present results establish coupled indel variants of TNNC2 as a novel molecular marker for meat quality improvement.

Effects of Polyunsaturated Fatty Acids Supplementation on the Meat Quality of Pigs: A Meta-Analysis

Polyunsaturated fatty acids (PUFAs) supplementation has been widely discussed as a strategy for improving meat quality in pig production, but the effects are inconsistent. This meta-analysis was performed to comprehensively evaluate its effects on the meat quality and growth performance of pigs. We searched the PubMed and the Web of Science databases (articles published from January 1, 2000 to October 16, 2020) and compared PUFAs-supplemented diets with control diets. We identified 1,670 studies, of which 14 (with data for 752 pigs) were included in our meta-analysis. The subgroup analysis was classified as PUFA source [conjugated linoleic acid (CLA) or linseed], concentration (high or low concentration), and initial stage (growing or finishing pigs). Our analysis found that PUFA supplementation increased the intramuscular fat (IMF) content (WMD = 0.467%, 95% CI: 0.312–0.621, p < 0.001), decreased the meat color L* (WMD = −0.636, 95% CI: −1.225 to −0.047, p = 0.034), and pH 24 h (WMD = −0.021, 95% CI: −0.032 to −0.009, p < 0.001) but had no influence on drip loss, meat color a* and b*, pH 45 min, and growth performance. CLA supplementation improved IMF content (WMD = 0.542%, 95% CI: 0.343–0.741, p < 0.001) and reduced meat color b* (WMD = −0.194, 95% CI: −0.344 to −0.044, p = 0.011). Linseed supplementation increased IMF content (WMD = 0.307%, 95% CI: 0.047–0.566, p = 0.021), decreased meat color L* (WMD = −1.740, 95% CI: −3.267 to −0.213, p = 0.026), and pH 24 h (WMD = 0.034, 95% CI: −0.049 to −0.018, p < 0.001). We discovered an increase on the IMF content in both high and low concentration PUFA supplementation (WMD = 0.461%, 95% CI: −0.344 to −0.044, p < 0.001; WMD = 0.456%, 95% CI: 0.276–0.635, p < 0.001). Furthermore, we also found the effects of PUFA supplementation on meat color L* and pH 24 h are concentration- and stage-dependent. PUFA supplementation can improve the meat quality of pigs, which mainly emerges in greatly increasing IMF content.

Effects of dietary nicotinic acid supplementation on meat quality, carcass characteristics, lipid metabolism, and tibia parameters of Wulong geese

The purpose of this study was to evaluate the effects of nicotinic acid (NA) supplementation on the meat quality, carcass characteristics, lipid metabolism, and tibia parameters in Wulong geese. A total of 360 twenty-nine-day-old Wulong geese were randomly divided into 6 treatments, and each treatment included 6 pens with 10 birds per pen. Birds were fed a basal diet supplemented with 0, 20, 40, 60, 80, or 100 mg/kg NA for 12 wk. Dietary NA supplementation linearly decreased L* value and increased pH and water-holding capacity in the breast muscle (P < 0.05). Increasing NA levels linearly and quadratically decreased shear force of breast muscle (P < 0.001). Dietary NA supplementation linearly reduced the thickness of subcutaneous fat plus the skin and percentage of abdominal fat, and enhanced the width of intermuscular fat band (P < 0.001). Dietary NA addition linearly and quadratically increased intramuscular fat (IMF) content (P ≤ 0.001). Increasing NA levels decreased serum total cholesterol and low-density lipoprotein cholesterol levels and increased serum lipase activity and hepatic mRNA expression of lipoprotein lipase in a linear manner (P < 0.05). There were linear and quadratic effects in serum triglycerides and high-density lipoprotein cholesterol (HDL-C) levels and malate dehydrogenase activity with the NA addition (P < 0.05). Feeding the NA-supplemented-diets linearly increased tibia length, circumference, fat-free dry weight, and ash content (P < 0.001). There were linear and quadratic increases in Ca and P contents with the NA supplementation (P < 0.05). According to the quadratic regression analyses fitted to shear force, IMF content, serum triglycerides and HDL-C levels, and tibial Ca and P contents, the optimal dietary NA supplementation was 80 to 90 mg/kg. In conclusion, NA addition enhanced meat quality and IMF content, regulated lipid metabolism, and increased tibia quality of Wulong geese. The dosage of 80 mg/kg NA in Wulong geese aged 5 to 16 wk was recommended.

Meat eating and nutritional quality of lambs sired by high and low muscle density rams

Intramuscular fat (IMF) content affects eating and nutritional quality of lamb meat. Muscle density measured by computer tomography is an in vivo proxy measure of IMF content that affects eating and nutritional quality of lamb meat. Lambs sired by high muscle density (HMD) or low muscle density (LMD) rams, selected for slaughter on commercial criteria were measured for meat quality and nutritional traits. A restricted maximum likelihood model was used to compare lamb traits. Additionally, regression analysis of sire estimated breeding value (EBV) for muscle density was performed for each meat quality trait. Muscle density EBV had a negative regression with IMF content (P < 0.001). For each unit increase in muscle density EBV, there was a significant decrease in loin (−1.69 mg/100 g fresh weight) and topside IMF (−0.03 mg/100 g fresh weight). Muscle density EBV had a negative regression with grouped saturated and monounsaturated fatty acids concentration (and monounsaturated proportion P < 0.001). Muscle density EBV had a negative regression with loin sensory traits tenderness, juiciness and overall liking and many novel tenderness sensory traits measured (P < 0.05). Selecting for LMD EBV increased IMF content and favourable meat eating quality traits. In contrast, sire muscle density EBV had a positive regression with loin polyunsaturated:saturated fat ratio and grouped polyunsaturated proportion traits (including total polyunsaturated proportion, total omega-6 (n-6) and total omega-3 (n-3) fatty acids (P < 0.001). This is explained by the fact that as sire muscle density EBV increases, polyunsaturated fatty acid proportion increases and the proportion of saturated and monounsaturated fatty acid content decreases. Muscle density EBV had a positive regression with shear force and the novel toughness sensory traits (P < 0.05). Selection for HMD EBV's increased shear force and toughness traits, which is unfavourable for the consumer. Low muscle density sired meat had higher meat colour traits chroma/saturation (+0.64, SD 2.30, P = 0.012), redness (+0.52, SD 1.91, P = 0.012) and yellowness (+0.31, SD 1.49, P = 0.08) compared to HMD sired meat. Selection for LMD could be used within a breeding programme to increase IMF content and enhance both meat colour and improve eating quality parameters.

Effects of carcass weight increase on meat quality and sensory properties of pork loin.

The objective of this study was to investigate the influence of increasing carcass weight (CW) on meat quality traits including meat color, water-holding capacity (WHC), tenderness, backfat thickness and intramuscular fat (IMF) content of pork loin. A total of 96 pork carcasses (48 LYD [Landrace × Yorkshire × Duroc] barrows and gilts) were selected at a commercial slaughterhouse. Each gender had commercial CW (≤ 90 kg), heavy CW (91–100 kg) and very heavy CW (> 100 kg) (16 carcasses from each CW group). Loin cuts (Longissimus lumborum) were excised to investigate meat color (CIE L*a*b*), drip loss, cooking loss, released water, Warner-Bratzler shear force (WBSF), and IMF content. Backfat thickness and IMF content of pork loin samples were significantly (p < 0.05) increased with increasing CW, although there was no significant difference in ultimate pH (pHu). CIE a* increased significantly (p < 0.05) with increasing CW, while there were no significant differences in CIE L* or CIE b* among CW groups. Although all WHC measures showed no significant differences among CW groups, WBSF increased significantly (p < 0.01) with increasing CW. Sensory flavor score was significantly increased while panel score for tenderness was decreased significantly (p < 0.001) with increasing CW. Consequently, CW had a positive correlation with flavor but negative correlation with tenderness. These results indicate that the increased IMF content improves flavor, juiciness and palatability, although tenderness deteriorates with increasing CW.

Reduced protein diets increase intramuscular fat of psoas major, a red muscle, in lean and fatty pig genotypes

The present study aims to assess the effects of pig’s genotype (lean v. fatty) and dietary protein level (control v. reduced) on intramuscular fat (IMF) content, fatty acid composition and fibre profile of psoas major, a representative red muscle in pig’s carcass scarcely studied relative to white longissimus lumborum. The experiment was conducted on 40 intact male pigs (20 Alentejana purebred and 20 Large White×Landrace×Pietrain crossbred) from 60 to 93 kg of live weight. Pigs were divided and allocated to four dietary groups: control protein diet equilibrated for lysine (17.5% of CP and 0.7% of lysine) and reduced protein diet (RPD) not equilibrated for lysine (13.1% of crude protein and 0.4% of lysine) within a 2×2 factorial arrangement (two genotypes and two diets). Alentejana purebred had higher IMF content (15.7%) and monounsaturated fatty acids (MUFA) (8.9%), whereas crossbred pigs had higher PM weight (46.3%) and polyunsaturated fatty acids (PUFA) (20.1%). The genotype also affected colour with higher lightness (15.1%) and yellowness (33.8%) and lower redness (9.9%) scores in crossbred pigs. In line with this, fatty pigs displayed more oxidative fibres (29.5%), whilst lean pigs had more glycolytic (54.4%). Relative to fatty acids, RPD increased MUFA (5.2%) and SFA (3.2%) but decreased PUFA (14.8%). Ultimately, RPD increased IMF content (15.7%) in the red muscle under study, with no impact on glycolytic to oxidative fibre type transformation.

Increased expression of thyroid hormone responsive protein (THRSP) is the result but not the cause of higher intramuscular fat content in cattle.

Thyroid hormone responsive protein (THRSP) is known to be involved in lipogenic processes in rodents. In cattle, THRSP could be a potential molecular marker for intramuscular fat (IMF) deposition since mRNA abundance was frequently found to be increased in skeletal muscle with high IMF content compared to those with low IMF. The aim of this study was to elucidate the background of this differential expression and to evaluate the role of THRSP as candidate for increased IMF content in cattle. By combination of mRNA and protein analyses, we could demonstrate that THRSP is present mainly in nuclei of adipose tissue, in intramuscular fat cells and associated cells, and in cells of the portal triad of liver, whereas muscle cells did not express THRSP. Cell culture analyses revealed furthermore that THRSP is expressed in mature adipocytes rather than in early stages of adipogenesis. Collectively, our data support the putative role of THRSP as transcriptional regulator and demonstrate that an increased expression of THRSP in M. longissimus is a consequence of but not the reason for a higher number of intramuscular adipocytes in cattle with enhanced IMF deposition.

Effects of diets containing different concentrations of energy on growth performance and carcass traits of geese from 28 to 70 days of age

Supplementation of dietary energy could reduce daily feed intake, decrease the feed/gain ratio, and increase intramuscular fat content. Based on broken-line regression analysis, the optimal concentrations of dietary energy for Sichuan White geese from 28 to 70 d was 12.56 MJ AME/ kg DM for minimum ADFI and 13.09 MJ AME/kg DM for optimum FGR, respectively.

Association of H-FABP gene polymorphisms with intramuscular fat content in Three-yellow chickens and Hetian-black chickens.

BackgroundTo explore the relationship between the heart-type fatty acid binding protein (H-FABP) gene and intramuscular fat (IMF), a polymorphism of the second exon of the H-FABP gene was investigated in 60 Three-yellow chickens (TYCs) and 60 Hetian-black chickens (HTBCs).ResultsThe IMF contents of the cardiac, chest and leg muscles in HTBC were increased compared with TYC. Both TYC and HTBC populations exhibited Hardy-Weinberg Equilibrium (HWE) according to the χ2 test. Three variations of the two birds were detected, namely, G939A, G982A and C1014T. HTBCs with the TT genotypes exhibit increased IMF content in the chest muscles compared with the TC genotype. Thus, the G982A site could be considered a genetic marker for selecting increased IMF content in the chest muscles of HTBC. The correlation coefficients revealed that H-FABP mRNA expression was negatively correlated with the IMF content in the cardiac, chest and leg muscles of HTBC and in the cardiac and chest muscles of TYC. The relative mRNA expression of H-FABP was reduced in the cardiac and leg muscles of HTBC compared with TYC, but this difference was not observed at the protein level, as assessed by Western blot analysis.ConclusionsThese findings offer essential data that can be useful in the breeding program of HTBC and future research exploring the role of H-FABP in IMF deposition and regulation in chickens.

Effect of betaine and arginine in lysine-deficient diets on growth, carcass traits, and pork quality.

Forty entire male pigs from a commercial crossbreed (Duroc × Large White × Landrace) were used to investigate the individual or combined effects of betaine and Arg supplementation in Lys-deficient diets on growth performance, carcass traits, and pork quality. Pigs with 59.9 ± 1.65 kg BW were randomly assigned to 1 of 5 dietary treatments ( = 8). The 5 dietary treatments were normal Lys and CP diet (0.51% Lys and 16% CP; control), reduced Lys and CP diet (0.35% Lys and 13% CP), reduced Lys and CP diet with betaine supplementation (0.33%), reduced Lys and CP diet with Arg supplementation (1.5%), and reduced Lys and CP diet with betaine and Arg supplementation (0.33% betaine and 1.5% Arg). Pigs were slaughtered at 92.7 ± 2.54 kg BW. The Lys-deficient diets (-35% Lys) increased intramuscular fat (IMF) content by 25% ( = 0.041) and meat juiciness by 12% ( = 0.041) but had a negative effect on growth performance ( < 0.05) of pigs. In addition, Lys-deficient diets increased L* ( = 0.005) and b* ( = 0.010) muscle color parameters and perirenal fat deposition ( < 0.001) and decreased both HCW ( = 0.015) and loin weight ( = 0.023). Betaine and Arg supplementation of Lys-deficient diets had no effect on IMF content but increased ( < 0.05) overall pork acceptability. Arginine supplementation also increased ( = 0.003) meat tenderness. Differences in fatty acid composition of pork were not detected among dietary treatment groups. However, oleic acid was positively correlated ( < 0.05) with IMF content, juiciness, flavor, and overall acceptability of meat. Data confirm that dietary CP reduction enhances pork eating quality but negatively affects pigs' growth performance. Moreover, it is suggested that betaine and Arg supplementation of Lys-deficient diets does not further increase IMF content but improves some pork sensory traits, including overall acceptability.

Phenotypic Correlations of Backfat Thickness with Meatiness Traits, Intramuscular Fat, &lt;i&gt;Longissimus&lt;/i&gt; Muscle Cholesterol and Fatty Acid Composition in Pigs

The aim of the present study was to determine the phenotypic correlations of backfat thickness with meatiness traits and intramuscular fat, cholesterol and fatty acid composition in the longissimus muscle of pigs. For this study, 60 barrows and 60 gilts (Pietrain × Duroc boars and Polish Large White crossbred sows) were slaughtered at 100 kg bodyweight. Lean meat percentage (LMP), loin muscle area (LMA), backfat thickness measured at five locations and average backfat thickness (ABF), and intramuscular fat (IMF), cholesterol (CHLM) and fatty acid composition in the longissimus muscle were determined. Phenotypic correlations of individual backfat thickness measured at five locations and ABF with LMP, LMA and polyunsaturated fatty acids (PUFAs), including C18 :2n-6, were negative and moderate to high, while with monounsaturated fatty acids (MUFAs), including C16:1 and C18:1 were positive and very low. Correlations of individual backfat thickness and ABF with saturated fatty acids (SFAs) and C16:0 were positive (0.29 to 0.56), while for C18:0 were low (0.10 to 0.23). Correlations of IMF and CHLM with LMP, LMA and PUFAs, especially C18:2n-6, were negative and high, while with SFAs and MUFAs were positive and moderate to high. Correlation between IMF and CHLM was high (0.74). The results of the present study indicate that increased IMF content results a significant decrease in carcass meatiness (LMP and LMA) and of PUFAs content and an increase in backfat thickness and contents of SFAs, MUFAs and CHLM. Keywords: Intramuscular Chemical Compositions, Muscle, MUFA, PUFA, Swine

Dietary L-arginine supplementation affects the skeletal longissimus muscle proteome in finishing pigs.

Forty-eight Duroc x Landrace x Large White gilts were used to determine the relationship between proteome changes of longissimus muscle and intramuscular fat (IMF) content in arginine-supplemented pigs. Beginning at 60 kg BW, pigs were fed a corn- and soybean meal-based diet supplemented or not with 1% L-arginine until they reached a BW of 100 kg. Supplementation with 1% L-arginine did not affect the growth performance or carcass traits, while it increased IMF content by 32% (P < 0.01), it also decreased the drip loss at 48 h post-mortem and the b* meat color value at 24 h post-mortem; supplementation with 1% dietary L-arginine did not change the proportion of SFA and MUFA in muscle lipids. The proteome changes in longissimus muscle between the control and supplemented pigs showed that L-arginine significantly influenced the abundance of proteins related to energy metabolism, fiber type and structure. The increase in IMF content was positively correlated with the increased abundance of slow twitch troponin I (TNNI1) protein and negatively correlated with myosin heavy chain IIb (MyHC IIb) protein content. It is suggested that the proteome changes in longissimus muscle contributed to the greater IMF content in L-arginine supplemented pigs.