Intramuscular Depots Research Articles

White Adipose Tissue Heterogeneity in the Single-Cell Era: From Mice and Humans to Cattle.

Adipose tissue is a major modulator of metabolic function by regulating energy storage and by acting as an endocrine organ through the secretion of adipokines. With the advantage of next-generation sequencing-based single-cell technologies, adipose tissue has been studied at single-cell resolution, thus providing unbiased insight into its molecular composition. Recent single-cell RNA sequencing studies in human and mouse models have dissected the transcriptional cellular heterogeneity of subcutaneous (SAT), visceral (VAT), and intramuscular (IMAT) white adipose tissue depots and revealed unique populations of adipose tissue progenitor cells, mature adipocytes, immune cell, vascular cells, and mesothelial cells that play direct roles on adipose tissue function and the development of metabolic disorders. In livestock species, especially in bovine, significant gaps of knowledge remain in elucidating the roles of adipose tissue cell types and depots on driving the pathogenesis of metabolic disorders and the distinct fat deposition in VAT, SAT, and IMAT in meat animals. This review summarizes the current knowledge on the transcriptional and functional cellular diversity of white adipose tissue revealed by single-cell approaches and highlights the depot-specific function of adipose tissue in different mammalian species, with a particular focus on recent findings and future implications in cattle.

Possible Mechanisms Linking Obesity, Steroidogenesis, and Skeletal Muscle Dysfunction.

Increasing evidence suggests that skeletal muscles may play a role in the pathogenesis of obesity and associated conditions due to their impact on insulin resistance and systemic inflammation. Skeletal muscles, as well as adipose tissue, are largely recognized as endocrine organs, producing biologically active substances, such as myokines and adipokines. They may have either beneficial or harmful effects on the organism and its functions, acting through the endocrine, paracrine, and autocrine pathways. Moreover, the collocation of adipose tissue and skeletal muscles, i.e., the amount of intramuscular, intermuscular, and visceral adipose depots, may be of major importance for metabolic health. Traditionally, the generalized and progressive loss of skeletal muscle mass and strength or physical function, named sarcopenia, has been thought to be associated with age. That is why most recently published papers are focused on the investigation of the effect of obesity on skeletal muscle function in older adults. However, accumulated data indicate that sarcopenia may arise in individuals with obesity at any age, so it seems important to clarify the possible mechanisms linking obesity and skeletal muscle dysfunction regardless of age. Since steroids, namely, glucocorticoids (GCs) and sex steroids, have a major impact on the amount and function of both adipose tissue and skeletal muscles, and are involved in the pathogenesis of obesity, in this review, we will also discuss the role of steroids in the interaction of these two metabolically active tissues in the course of obesity.

The relationship between the rumen microbiome and carcass merit in Angus steers.

The objective of this study was to explore the relationships between ruminal microbial populations from Angus steers that were divergent in carcass traits related to adipose accumulation. Twenty-four feedlot-finished Angus steers (age: 538 ± 21 d; body weight following lairage: 593.9 ± 43.7 kg) were slaughtered, and ruminal contents and carcass data were collected. Ruminal microbial deoxyribonucleic acid (DNA) extraction and 16S ribosomal ribonucleic acid (rRNA) gene sequencing were performed to determine microbial relative abundances, to estimate microbial diversity, and to predict microbial metabolic pathways. A variety of correlation analyses and one-way ANOVA were performed to investigate the relationships between the rumen microbiome and carcass traits. Marbling score (P = 0.001) and longissimus lipid content (P = 0.009) were positively correlated to Chao1 Richness Index, suggesting that increased intramuscular fat was associated with increased numbers of ruminal microbial species. The phyla Tenericutes and TM7 were negatively correlated (P ≤ 0.05) to marbling score and longissimus lipid content, indicating that lower abundances of these phyla may be associated with improvements in intramuscular fat content. Greater abundance of the bacterial family S24-7 was positively correlated (P = 0.002) to marbling score. Analysis by marbling classification revealed further linkages to microbial richness (P ≤ 0.063), diversity (P = 0.044), and S24-7 (P < 0.001) populations. Computational prediction of the microbial metabolic pathways revealed no differences (P ≥ 0.05) in metabolic pathway expression in rumen microbes between steers in the high- and low-marbling classes. Several phyla, families, and genera were positively correlated (P ≤ 0.05) to both rib fat thickness and yield grade. Collectively, our results suggest that microbial composition is associated to differing performance in carcass adipose traits. Overall, most of the bacterial taxa correlated to the intramuscular and subcutaneous fat depots did not overlap, suggesting the microbial population end products likely impacted adipose accumulation largely via separate adipogenic pathways of the host animal.

Investigation of the Fatty Acid Profile of the M. rhomboideus Derived from Bos indicus Cattle

ObjectivesResearch has shown the m. Rhomboideus (Rho) from purebred Bos indicus (BI) to be unique in its proximate chemical composition, indicated by increased lipid deposition. Thus, potential for the depostion of mono- (MUFA) and poly- unsaturated (PUFA) fatty acids exists. The objective of this study was to assess the fatty acid composition of the intramuscular (IMF) and subcutaneous (SQF) depots in the Rho from BI crossed cattle.Materials and MethodsThree replications of 4 USDA Choice (Ch) and 4 USDA Select (Se) Rho muscles were selected from the right half of split carcasses (N = 24). Selection parameters were &gt; 7.62-cm hump height, &gt; 7.62-cm width, &gt; 25.4-cm length, weight range: 2–4-kg. Muscles were removed from carcasses and vacuum packaged. After a 14-d aging period, Rho muscles were fabricated, 2.54-cm serially cut steaks (anterior to posterior), trimmed to 0.254-mm fat thickness. Steaks were assigned identification tags and designated for analysis. Rho steaks were used for proximate composition (n = 2), trained sensory analysis (n = 2), Warner-Bratzler shear force (WBS, n = 1), collagen content (n = 1), and fatty acid composition of IMF and SQF (n = 1). Steaks for trained sensory analysis were also used for color measurements and cook yield. Data were analyzed using a 2-sample t test. Sensory data were analyzed using a linear fit model with order as a random effect. All data analyzed using JMP v14.0.0. A predetermined significance level of P &lt; 0.05 was used.ResultsTotal MUFA, PUFA and saturated fatty acid (SFA) percentages of IMF were not significant (P &gt; 0.05) between Ch Rho muscles (43, 7.2, 47.1%, 0.89, respectively) and Se Rho muscles (43.0, 6.3, 50.7%, 0.86, respectively). Mean averages across both quality grades for total MUFA, PUFA, SFA, and MUFA:SFA (42.2, 6.8, 48.9%, 0.87, respectively) in Rho IMF were similar to reported FAC averages of Bos taurus (BT) longissimus dorsi IMF (47.8, 4.4, 47.8%, 1.0, respectively).Total MUFA percentage (49.1 vs. 45.4%) and MUFA:SFA ratio (1.1 vs. 0.9) were significantly higher (P &lt; 0.001) in Ch SQF compared to Se SQF. However, total PUFA percentage (4.3 vs. 3.7%) and SFA (50.3 vs. 47.0%) were significantly higher (P &lt; 0.02) in Se SQF compared to Ch SQF. Mean averages across both quality grade for total MUFA, PUFA, SFA, and MUFA:SFA (47.4, 4, 48.6%, 0.99, respectively) in SQF were similar to reported fatty acid averages of BT brisket SQF (56.8, 3, and 35.9%; 1.47, respectively).Protein content (19.4 vs. 18.6%) was higher (P &lt; 0.02) for Ch than Se Rho muscles. L* value (50.2 vs. 47.9) was larger (P &lt; 0.05) for Se. Ch Rho muscles contained greater amounts (P &lt; 0.001) of total, insoluble, and soluble collagen (21.8, 21.5, 0.3 mg/g, respectively) compared to Se Rho muscles (13.8, 13.7, 0.1 mg/g, respectively). Ch Rho muscles were more tender (P &lt; 0.001) as determined by WBS values (2.6 vs. 3.1 kg). Trained sensory analysis, pH, fat, moisture, a* and b* color values between quality grades were not different (P &gt; 0.05).ConclusionDifferences were not seen for fatty acid composition between Ch and Se Rho IMF fat. However, higher percentages of total PUFA were found in both Ch and Se Rho IMF compared to reported longissimus dorsi IMF. Additionally, Ch Rho SQF contained higher percentages of total MUFA. However, Se Rho SQF contained higher percentages of total PUFA and SFA. Higher percentages of SFA were found in both Ch and Se SQF compared to reported brisket SQF SFA values.

Investigation of the Fatty Acid Profile of the M. rhomboideus Derived from Bos indicus Cattle

ObjectivesResearch has shown the m. Rhomboideus (Rho) from purebred Bos indicus (BI) to be unique in its proximate chemical composition, indicated by increased lipid deposition. Thus, potential for the depostion of mono- (MUFA) and poly- unsaturated (PUFA) fatty acids exists. The objective of this study was to assess the fatty acid composition of the intramuscular (IMF) and subcutaneous (SQF) depots in the Rho from BI crossed cattle.Materials and MethodsThree replications of 4 USDA Choice (Ch) and 4 USDA Select (Se) Rho muscles were selected from the right half of split carcasses (N = 24). Selection parameters were > 7.62-cm hump height, > 7.62-cm width, > 25.4-cm length, weight range: 2–4-kg. Muscles were removed from carcasses and vacuum packaged. After a 14-d aging period, Rho muscles were fabricated, 2.54-cm serially cut steaks (anterior to posterior), trimmed to 0.254-mm fat thickness. Steaks were assigned identification tags and designated for analysis. Rho steaks were used for proximate composition (n = 2), trained sensory analysis (n = 2), Warner-Bratzler shear force (WBS, n = 1), collagen content (n = 1), and fatty acid composition of IMF and SQF (n = 1). Steaks for trained sensory analysis were also used for color measurements and cook yield. Data were analyzed using a 2-sample t test. Sensory data were analyzed using a linear fit model with order as a random effect. All data analyzed using JMP v14.0.0. A predetermined significance level of P < 0.05 was used.ResultsTotal MUFA, PUFA and saturated fatty acid (SFA) percentages of IMF were not significant (P > 0.05) between Ch Rho muscles (43, 7.2, 47.1%, 0.89, respectively) and Se Rho muscles (43.0, 6.3, 50.7%, 0.86, respectively). Mean averages across both quality grades for total MUFA, PUFA, SFA, and MUFA:SFA (42.2, 6.8, 48.9%, 0.87, respectively) in Rho IMF were similar to reported FAC averages of Bos taurus (BT) longissimus dorsi IMF (47.8, 4.4, 47.8%, 1.0, respectively).Total MUFA percentage (49.1 vs. 45.4%) and MUFA:SFA ratio (1.1 vs. 0.9) were significantly higher (P < 0.001) in Ch SQF compared to Se SQF. However, total PUFA percentage (4.3 vs. 3.7%) and SFA (50.3 vs. 47.0%) were significantly higher (P < 0.02) in Se SQF compared to Ch SQF. Mean averages across both quality grade for total MUFA, PUFA, SFA, and MUFA:SFA (47.4, 4, 48.6%, 0.99, respectively) in SQF were similar to reported fatty acid averages of BT brisket SQF (56.8, 3, and 35.9%; 1.47, respectively).Protein content (19.4 vs. 18.6%) was higher (P < 0.02) for Ch than Se Rho muscles. L* value (50.2 vs. 47.9) was larger (P < 0.05) for Se. Ch Rho muscles contained greater amounts (P < 0.001) of total, insoluble, and soluble collagen (21.8, 21.5, 0.3 mg/g, respectively) compared to Se Rho muscles (13.8, 13.7, 0.1 mg/g, respectively). Ch Rho muscles were more tender (P < 0.001) as determined by WBS values (2.6 vs. 3.1 kg). Trained sensory analysis, pH, fat, moisture, a* and b* color values between quality grades were not different (P > 0.05).ConclusionDifferences were not seen for fatty acid composition between Ch and Se Rho IMF fat. However, higher percentages of total PUFA were found in both Ch and Se Rho IMF compared to reported longissimus dorsi IMF. Additionally, Ch Rho SQF contained higher percentages of total MUFA. However, Se Rho SQF contained higher percentages of total PUFA and SFA. Higher percentages of SFA were found in both Ch and Se SQF compared to reported brisket SQF SFA values.

Rats and rabbits as pharmacokinetic screening tools for long acting intramuscular depots: case study with paliperidone palmitate suspension

Development of prodrug of 9-hydroxyrisperidone (paliperidone) long-acting intramuscular injection has enabled delivery over four-week time period with improved compliance.The key aim of this work was to establish a reliable preclinical model which may potentially serve as a screening tool for judging the pharmacokinetics of paliperidone formulation(s) prior to human clinical work.Sparse sampling composite study was used in rats, (Wistar/Sprague–Dawley (SD; n = 10)) and a serial blood sampling study design was used in rabbits (n = 4). Animals received intramuscular injection of paliperidone palmitate in the thigh muscle at dose of 16 (rats) and 4.5 mg/kg (rabbits). Samples were drawn in rats (retro-orbital sinus) and rabbits (central ear artery) and were analysed for paliperidone using liquid chromatography–mass spectrometry/ mass spectrometry (LC-MS/MS) assay. The plasma data was subjected to pharmacokinetic analysis.Following intramuscular injection of depot formulation in Wistar/SD rats and rabbits, absorption of paliperidone was slow and gradual with median value of time to reach maximum concentration (Tmax) occurring on day 7. The exposures (i.e. area under the curve (AUC; 0–28) days) were 18,597, 21,865 and 18,120 ng.h/mL, in Wistar, SD and rabbits, respectively. The clearance was slow and supported long half-life (8–10 days).Either one of the two models can serve as a research tool for establishing pharmacokinetics of paliperidone formulation(s).

Intramuscular and subcutaneous drug depot characterization of a long-acting cabotegravir nanoformulation by MALDI IMS

Recently, researchers have begun exploring the use of injectable long-acting antiretroviral drug formulations that could improve treatment adherence by offering HIV patients infrequent dosing regimens (≥monthly), which is an attractive alternative to the daily oral dosing that is currently required. These drug nanosuspensions can be injected into patients intramuscularly or subcutaneously to form dissolution-controlled drug depots that deliver therapeutic drug concentrations over extended periods. Despite the potential advantages of long-acting injectables for the treatment of chronic conditions such as HIV infection, the mechanisms driving the in vivo dissolution and absorption profiles of these formulations are not well understood.The objective of this study was to assess the tissue distribution of cabotegravir long-acting (CAB-LA), an injectable antiretroviral medication, in rat intramuscular and subcutaneous injection depots 14-days after a single dose. Tissue sections containing the depots were analyzed by MALDI imaging mass spectrometry (IMS) and the results were correlated with the tissue histology. The data generated by MALDI IMS revealed high levels of cabotegravir (CAB) localized to both the intramuscular and subcutaneous injection depots with diffuse lower relative intensity signals throughout the surrounding tissue. Additionally, targeted high spatial resolution (5 μm pixel dimensions) MALDI IMS experiments revealed a unique distribution for the dipotassium adduct of CAB that was highly localized to multinucleated giant cells (MGCs) surrounding the depot. These data support the premise that the inflammatory tissue response associated with injection of CAB-LA may play an important role in the dissolution, absorption, and systemic distribution of CAB from the injection depots.

197 Added Fat Fed with 30% Dried Distillers Grains with Solubles to Pigs Alters Fatty Acid Composition in Four Fat Depots but Does Not Change Carcass Composition or Quality.

High inclusion levels of unsaturated dietary fat sources negatively impacts pork fat quality. Thus, the objective of this study was to evaluate supplementing swine diets with saturated animal fats to improve the fatty acid profile of pork carcasses. Forty individually reared barrows (100 kg ± 3 kg, PIC C23 x 337) were randomly assigned to one of five treatments containing dried distillers grains with solubles and 3% added fat to determine the resulting carcass characteristics and fresh pork quality. The treatments included (1) a positive control containing a corn and soybean meal base with 3% choice white grease (PCON), (2) 30% high protein dried distillers grain and 3% choice white grease (HPDDG), or 30% DDGS with (3) no added fat (DDGS), (4) 3% choice white grease (DDGS + CWG), or (5) 3% butter oil (DDGS + BO). Postmortem carcass characteristics and quality attributes were not different between diets (P > 0.08) except the semimembranosus muscle from pigs fed HPDDGS had a more basic ultimate pH (P = 0.01) compared to all other treatments. Approximately 5x5 cm square fat samples were collected at the cranial tip of the jowl at the site of head removal, on the evisceration midline caudal to sternum, but anterior to mammary tissue, and the three quarter distance around the LM at the 10th rib. Subcutaneous back fat was separated into inner and outer layers. Intramuscular fat was collected via a composite sample of the 10th rib loin chop. Diet changed (P < 0.01) SFA, MUFA and PUFA in subcutaneous, intramuscular, belly and jowl fat depots. Both layers of subcutaneous fat and belly fat were the most saturated in pigs fed PCON diet (P < 0.01) and contained the greatest proportions of SFA and MUFA. Including 30% DDGS in the diet increased (P < 0.01) PUFA and decreased MUFA content in subcutaneous fat layers, jowl and belly fat. However, in IMF, 30% DDGS in the diet increased (P < 0.01) SFA and MUFA. Butter oil in the diet markedly increased (P < 0.01) CLA (18:9c11t isomer) in subcutaneous, jowl and belly fat. Although added fat in the diet altered fatty acid composition in multiple fat depots, adding additional saturated fat in the form of butter oil to the diet did not significantly improve other measures of carcass quality.

MicroRNA-27b Depletion Enhances Endotrophic and Intravascular Lipid Accumulation and Induces Adipocyte Hyperplasia in Zebrafish.

miR-27b has emerged as a regulatory hub in cholesterol and lipid metabolism, and as a potential therapeutic target for treating atherosclerosis and obesity. However, the impact of miR-27b on lipid levels in vivo remains to be determined. Zebrafish lipids are normally stored as triacylglycerols (TGs) and their main storage sites are visceral, intramuscular, and subcutaneous lipid depots, and not blood vessels and liver. In this study, we applied microRNA-sponge (miR-SP) technology and generated zebrafish expressing transgenic miR-27b-SP (C27bSPs), which disrupted endogenous miR-27b activity and induced intravascular lipid accumulation (hyperlipidemia) and the early onset of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Oil Red O staining predominantly increased in the blood vessels and livers of larvae and juvenile C27bSPs, indicating that miR-27b depletion functionally promoted lipid accumulation. C27bSPs also showed an increased weight gain with larger fat pads, resulting from adipocyte hyperplasia. Molecular analysis revealed that miR-27b depletion increased the expression of genes that are associated with lipogenesis and the endoplasmic reticulum (ER). Moreover, miR-27b-SP increased peroxisome proliferator-activated receptor γ (PPAR-γ), CCAAT enhancer binding protein-α (C/EBP-α, and sterol regulatory element binding transcription factor 1c (SREBP-1c) expression and contributed to lipogenesis and adipogenesis. Conclusion: Our results suggest that miR-27b-SP acts as a lipid enhancer by directly increasing the expression of several lipogenic/adipogenic transcriptional factors, resulting in increased lipogenesis and adipogenesis. In this study, miR-27b expression improved lipid metabolism in C27bSPs, which suggests that miR-27b is an important lipogenic factor in regulating early onset of hyperlipidemia and adipogenesis in zebrafish.

Differential Relationship Between Thigh and Calf Intramuscular Adipose Tissue Depots and Indices of Metabolic Health in Older Overweight and Obese Adults

IntroductionAccumulation of intramuscular adipose tissue (IMAT) is associated with insulin resistance, but there are limited data comparing the predictive ability of different IMAT stores with markers of metabolic health.PurposeThe purpose of this secondary analysis study was to investigate associations among thigh and calf IMAT stores and indices of metabolic health in older overweight and obese adults.MethodsSeventy‐three subjects (25 men, 48 women, age: 58 ± 11 y, BMI: 29.9 ± 4.9 kg/m2, mean ± SD) completed dietary interventions with (n=48) or without (n=25) energy restriction‐induced weight loss and thigh and calf compositions were assessed via magnetic resonance imaging. IMAT, IMAT volume to total tissue volume (TT) ratio, and IMAT to muscle tissue volume (MT) ratio were regressed separately against fasting serum glucose, insulin, homeostatic model assessment‐insulin resistance (HOMA‐IR), and lipid‐lipoprotein profile parameters. A multiple linear regression modeling procedure was performed on baseline (adjusted for age and sex) and change values (adjusted for age, sex, baseline dependent variable) and adjusted regression coefficients (β*) are reported. Significance level was set at p&lt;0.05 and all β* values herein meet significance.ResultsThigh IMAT is predictive of metabolic health parameters, while calf IMAT is not. Conversely, changes in calf IMAT from dietary intervention predict improvement of metabolic health indices, whereas thigh IMAT does not. Baseline thigh IMAT was associated with fasting serum insulin, HOMA‐IR, and serum triacylglycerol (TG). Baseline thigh IMAT:TT was associated with fasting serum glucose, insulin, HOMA‐IR, TG, total cholesterol (TC), and inversely associated with TC:HDL, while baseline thigh IMAT:MT was associated with TC and TG. There were no associations between baseline calf IMAT variables and metabolic health indices. No associations were detected between changes (Δ) in thigh IMAT and Δs in metabolic health indices. However, calf ΔIMAT was associated with Δ insulin, ΔHOMA‐IR, ΔTG, ΔTC and inversely associated with ΔTC:ΔHDL. Calf ΔIMAT:ΔMT was associated with Δ insulin, ΔHOMA‐IR, and ΔTC.ConclusionsThese data support the consensus that IMAT is associated with insulin resistance, and implicate IMAT to impact lipid‐lipoprotein profile. Further, improvement in metabolic health indices may be better predicted by changes in calf IMAT than by changes in thigh IMAT in older overweight and obese adults participating in weight loss and weight stability dietary interventions.Support or Funding InformationPurdue Center for Aging and Life Course; American Egg Board‐Egg Nutrition Center; National Dairy Council; NIH UL1TR001108; Purdue Ingestive Behavior Research Center

Simultaneous magnetic resonance imaging and pharmacokinetic analysis of intramuscular depots

The present pilot study introduces a method that might give novel insights in drug absorption processes from intramuscularly administered depots.An oily suspension or an aqueous solution of paracetamol (6mg/kg body mass), prednisolone or its hemisuccinate sodium salt for the aqueous solutions (10mg/kg body mass) or diclofenac (10mg/kg body mass) was injected into the muscle tissue of the hind leg of female Lewis-rats (n=47). For the oily suspensions the micronized particles were suspended in medium-chain triglycerides. The aqueous solutions were buffered to a pH of 7.4±0.5. Polyethylene glycol was added as a cosolvent in the formulations containing paracetamol (acetaminophen) and diclofenac and sodium chloride was added to the aqueous solutions of prednisolone hemisuccinate sodium to achieve nearly isotonic formulations. The formed depot was visualized by magnetic resonance imaging (MRI) and characterized with regard to volume and surface area. A 7T-small animal scanner was used and T1-weighted and T2-weighted sequences including a fat saturation were performed. Simultaneously blood samples were taken and the drugs were quantitatively analyzed.The water based solvent and the oily dispersion agent were visible in the MRI images without the use of contrast agents. Since a free hand injection mostly led to an application directly into the fascia, resulting in a fast removal of the depot, MRI-guided injection was conducted. Comparing pharmacokinetic data with MRI data it was observed that maximal blood levels occurred before the solvent and the dispersion agent were removed from the muscle tissue. Thus, the drug is not absorbed together with the depot. Furthermore, no correlation was found between the shape of the depot and the rate of absorption. Consequently, a higher surface area or volume of the depot did not result in a faster release or absorption of the drugs from the tested formulations. In contrast to the paracetamol and prednisolone formulations the formulations containing diclofenac led to a massive accumulation of interstitial fluid around the injection area being a sign for an acute local reaction. Histological analysis of the muscle tissue revealed a clear correspondence between the amount of interstitial fluid and the extent of infiltrating lymphocytes and granulocytes indicating a tissue response.In conclusion combining MRI with pharmacokinetic data is a suitable method to gain deeper insights into drug absorption processes from intramuscular depots. Furthermore, MRI offers a great possibility detecting local side effects caused by an intramuscularly applied dosage form. This might be very useful in preclinical phases during the development of new intramuscular formulations.

Association study between variability in the SCD gene and the fatty acid profile in perirenal and intramuscular fat deposits from Spanish goat populations

Despite the fact that goat meat is an important nutritive source throughout the world, aspects related to its characterization, and in particular genetic issues, have rarely been studied. Our objective was to assess the variability of the Stearoyl-CoA desaturase (SCD) gene in a sample of Spanish goat populations bred for both meat and dairy purposes and to look for possible associations between this genetic variability and the fatty acid composition in two fat deposits of industrial interest (perirenal and intramuscular). To do this, a goat population of 140 male suckling kids belonging to meat and dairy breeds was selected from farms in southern Spain. Four markers were detected in the SCD gene (SCD2, SCD3 172, SCD3 181, and SCD3 231) in the population, and significant associations were found between these markers and five individual fatty acids: C8:0, C11:0, C15:1, C16:1cis-9 and CLA 10 trans-12cis and two groups of fatty acids: SFA and MUFA. While significant associations in early (perirenal) fat depots for both dairy and meat purposes were observed, the only significant association in late (intramuscular) depots was found in goat kids bred for meat purposes. The SCD has been shown to be a useful gene to estimate the potential to show the different amounts of fatty acids in the fat of goat kids and use it in improvement programs which might provide an added value to goat meat and might help to produce a more competitive final product.

Effect of linseed dietary supplementation on adipose tissue development, fatty acid composition, and lipogenic gene expression in lambs

The objective of this study was to examine the effect of linseed supplementation on growth and carcass parameters, adipocyte cellularity, lipogenic enzyme activity, fatty acid (FA) composition and expression of lipogenic genes in subcutaneous (SC) adipose tissue and intramuscular (IM) adipose tissue of longissimus thoracis muscle of lambs. Thirty-six male Navarra breed lambs allocated into 3 experimental groups (15.2±0.18kg) were fed a control diet (containing barley and soya) and two experimental diets (5% and 10% linseed, L5 and L10 respectively) and slaughtered at 26.5±0.28kg. In the SC adipose tissue and muscle, the activity of fatty acid synthetase (FAS), glycerol 3-phosphate dehydrogenase (G3PDH), glucose 6-phosphate dehydrogenase (G6PDH) and NADP-Isocitrate dehydrogenase (ICDH) was studied and the expression of lipoprotein lipase (LPL), acetyl-CoA carboxylase 1or alpha (ACACA), stearoyl-CoA desaturase (SCD), fatty acid desaturase 1 (FADS1) and 2 (FADS2) and fatty acid elongase 5 (ELOVL5) was quantified. Addition of linseed, rich in α-linolenic acid (C18:3n−3), had no effect on growth and carcass parameters. Linseed supplementation increased C18:3n−3, C18:1t10 + C18:1t11 and total n−3 polyunsaturated fatty acid (PUFA) contents of SC and IM fat (P<0.001) and decreased C18:2n−6 and C18:3n−6 (P<0.05). The n−6/n−3 ratio was also decreased by linseed addition (P<0.05). There were no significant effects of linseed on C18:2c9,t11, eicosapentaenoic acid (C20:5n−3), docosapentaenoic acid (C22:5n−3) and docosahexaenoic acid (C22:6n−3) contents of SC and IM depots. In the SC fat, expression of ACACA and SCD was downregulated in L10 compared to C group (P<0.001) and LPL was upregulated in L5 group (P<0.001); however, there were no effects of diet on FADS1, FADS2 and ELOVL5 mRNA levels. In the IM fat, downregulation of ACACA (L5 and L10), SCD (L10), FADS1 (L5 and L10) and FADS2 (L5) was observed (P<0.001). Expression of LPL was upregulated in L5 compared to C group (P<0.01). It was concluded that dietary linseed raised C18:3n−3 and n−3 PUFA in SC and IM fat in Navarra breed lambs and modified the FA synthesis through the regulation of key-lipogenic gene expression. Dietary linseed regulated de novo FA synthesis and shifted monounsaturated FA formation at the transcriptional level by downregulating ACACA and SCD, respectively. Hence, linseed supplementation did not appear to enhance the synthesis of C18:2c9,t11. Moreover, dietary PUFA affected the expression of genes involved in long chain PUFA synthesis (FADS1, FADS2 and ELOVL5) in a tissue-specific manner.

The influence of maternal energy status during midgestation on beef offspring carcass characteristics and meat quality.

Research has suggested that maternal undernutrition may cause the development of a thrifty phenotype in the offspring, potentially resulting in greater adiposity and reduced muscle mass. These alterations in adipose and muscle development could have lasting impacts on offspring growth, carcass characteristics, and meat quality. However, limited research exists evaluating the impact of maternal energy status on these economically important traits of the offspring. Therefore, the objective of this study was to determine the influence of maternal energy status during midgestation on offspring carcass characteristics and meat quality. To alter maternal energy status, cows either grazed dormant, winter range (positive energy status [PES]) or were fed in a drylot at 80% of the energy requirements for BW maintenance (negative energy status [NES]) during a mean period of 102 ± 10.9 to 193 ± 10.9 d of gestation. Changes in BCS, BW, LM area (LMA), and 12th rib backfat were measured throughout midgestation. At the end of midgestation, cows in the NES group had a reduction (P ≤ 0.05) in BCS, BW, LMA, and 12th rib backfat when compared with PES dams. Cows and calves were managed similarly after midgestation through weaning and calves were managed and fed a common diet through the receiving, backgrounding, and finishing phases in the feedlot. Calves were harvested after 208 d in the feedlot, carcass characteristics were recorded, and strip loins were recovered for analysis of objective color and Warner-Bratzler shear force (WBSF). Maternal energy status had no influence on offspring HCW, dressing percent, LMA, percent KPH, marbling score, percent intramuscular fat, objective color, or WBSF (P > 0.10). Progeny of NES cows tended to have improvements in 12th rib backfat and USDA yield grade (P < 0.10). Greater ratio of marbling score to 12th rib fat thickness and ratio of percent intramuscular fat to 12th rib fat thickness (P < 0.05) were discovered in progeny from cows experiencing a NES during midgestation. These results suggest that maternal energy status during midgestation may impact fat deposition in intramuscular and subcutaneous fat depots without impacting muscle mass.

Equine model for soft-tissue regeneration.

Soft-tissue regeneration methods currently yield suboptimal clinical outcomes due to loss of tissue volume and a lack of functional tissue regeneration. Grafted tissues and natural biomaterials often degrade or resorb too quickly, while most synthetic materials do not degrade. In previous research we demonstrated that soft-tissue regeneration can be supported using silk porous biomaterials for at least 18 months in vivo in a rodent model. In the present study, we scaled the system to a survival study using a large animal model and demonstrated the feasibility of these biomaterials for soft-tissue regeneration in adult horses. Both slow and rapidly degrading silk matrices were evaluated in subcutaneous pocket and intramuscular defect depots. We showed that we can effectively employ an equine model over 6 months to simultaneously evaluate many different implants, reducing the number of animals needed. Furthermore, we were able to tailor matrix degradation by varying the initial format of the implanted silk. Finally, we demonstrate ultrasound imaging of implants to be an effective means for tracking tissue regeneration and implant degradation.

Improvement of fatty acid profiles in kid meat from Murciano-Granadina goats under semi-arid environment

The present paper shows the results of a comparison of the fatty acid profile of kid meat obtained from extensive management system under semi-arid conditions and conventional systems. Meat samples from 61 Murciano-Granadina goat kids reared in extensive management system (9 females, 12 males) under semi-arid conditions and two variants of conventional managing systems, intensive with natural rearing (9 females, 11 males) and intensive with artificial rearing (10 females, 10 males), were used in the present study. Kids reared under the extensive management system showed (P < 0.05) that their intramuscular fat depots had the lowest percentage of myristic acid (12.31%) and the highest percentage of oleic acid (36.66%). A strong influence of physical activity during grazing in pasture modulated the fatty acid profile in muscle of kids reared under the extensive management system. Kids from this management system show a trend to produce healthier meat relative to intensive with natural and with artificial rearing management systems, as reflected by the fact that the lowest atherogenicity index was measured in intramuscular fat from kids reared under extensive management system.

A comparative study of fatty acid profiles of fat in commercial Spanish suckling kids and lambs

Fatty acid profiles are a major contributor to meat quality in small ruminants. Nevertheless, while fatty acid profiles from suckling lambs have been extensively studied they are virtually unknown in suckling kids. Fatty acid profiles of intramuscular and kidney knob fat depots of suckling kids were compared with fatty acid profiles of lambs with a quality label in the Spanish market. Forty suckling kids from Blanca Celtibérica (BC), Moncaína (Mo), Negra Serrana (NS) and Murciano Granadina (MG) breeds and 20 Churra male suckling lambs labelled with ‘Lechazo de Castilla y León’ Protected Geographic Indication were slaughtered at commercial live weights (12 kg). In both depots differences in the unsaturated fatty acid profile were observed between breeds. The most pronounced differences were observed between meat goat breeds (BC, Mo and NS) and lambs, whilst a greater similarity in the fatty acid profile was observed between kids from dairy goat breeds (MG) and lambs. The lowest polyunsaturated fatty acid content was observed in meat goat breeds (approximately 21 to 22% of total fatty acids detected in the intramuscular fat). No significant differences in atherogenic index and desirable fatty acid content (range 68 to 70% of total fatty acids detected) were observed. However, a more favourable (lower than 8.07) n-6/n-3 ratio was observed in meat goat breeds. The use of fatty acid profiles from intramuscular and kidney knob fat could be proposed as a tool to differentiate goat kids and lambs. The fact that intramuscular fat from suckling kids and lambs shows appropriate lipid nutritional indices and their low carcass fatness indicate that moderate consumption of suckling kid and lamb meat may contribute to an overall balanced diet for humans.

High-fat diet reduces local myostatin-1 paralog expression and alters skeletal muscle lipid content in rainbow trout, Oncorhynchus mykiss

Muscle growth is an energetically demanding process that is reliant on intramuscular fatty acid depots in most fishes. The complex mechanisms regulating this growth and lipid metabolism are of great interest for human health and aquaculture applications. It is well established that the skeletal muscle chalone, myostatin, plays a role in lipid metabolism and adipogenesis in mammals; however, this function has not been fully assessed in fishes. We therefore examined the interaction between dietary lipid levels and myostatin expression in rainbow trout (Oncorhynchus mykiss). Five weeks of high-fat diet (HFD; 25% lipid) intake increased white muscle lipid content and decreased circulating glucose levels and hepatosomatic index when compared to low-fat diet (LFD; 10% lipid) intake. In addition, HFD intake reduced myostatin-1a and myostatin-1b expression in white muscle and myostatin-1b expression in brain tissue. Characterization of the myostatin-1a, myostatin-1b, and myostatin-2a promoters revealed putative binding sites for a subset of transcription factors associated with lipid metabolism. Taken together, these data suggest that HFD may regulate myostatin expression through cis-regulatory elements sensitive to increased lipid intake. Further, these findings provide a framework for future investigations of mechanisms describing the relationships between myostatin and lipid metabolism in fish.

Effects of different sources of fat (calcium soap of palm oil vs. extruded linseed) in lactating ewes' diet on the fatty acid profile of their suckling lambs

The main objective of this study was to evaluate the effects of supplementing lactating ewe diets with extruded linseed on the fatty acid (FA) composition of intramuscular and subcutaneous fat depots of suckling lambs. Twenty-four pregnant Churra ewes were divided into two groups based on the milk production, age, body weight and parity, and assigned to one of two treatments. Each ewe of the Control treatment was supplemented with 70g/day of FAs from a calcium soap of palm oil, while the other treatment group (Lin) was supplemented with 128g/day of extruded linseed. All lambs were reared exclusively on milk and were slaughtered when they reached 11kg live weight. FA profiles of ewe milk, lamb meat and subcutaneous adipose tissue were determined by GC. Lamb performance was not affected by the treatments. Muscle fat and adipose tissue from the Lin treatment showed higher proportions of polyunsaturated fatty acids (PUFA). The percentages of α-linolenic (C18:3 n−3), docosahexaenoic (C22:6 n−3), vaccenic (trans-11 C18:1) and rumenic (cis-9, trans-11 C18:2) acids in both fat depots were higher in Lin than in Control suckling lambs. Furthermore, meat fat from Lin carcasses displayed a lower n−6/n−3 ratio than Control samples. Intramuscular depots clearly showed a greater content of PUFA, including cis-9, trans-11 C18:2, and a lower n−6/n−3 ratio than subcutaneous fat. The results from this study demonstrate that dietary extruded linseed supplementation of lactating ewes enhances the nutritional quality of suckling lamb fat depots such as intramuscular and subcutaneous fats.

Effects of low protein diets on pigs with a lean genotype 2. Compositional traits measured with computed tomography (CT)

The effects on compositional changes across the growing-finishing period (40–115kg) of feeding pig diets with different protein and amino acid levels were investigated using CT scanning (at 60, 85 and 115kg live weight). Pigs of a lean commercial genotype were fed a commercial control regime (C), or a low protein regime with either high (LP1) or low (LP2) essential amino acid levels, all balanced for net energy. In vivo CT measurements agreed well with post-slaughter sample joint dissection results for carcass tissue weights/proportions, and CT-measured muscle density predicted intramuscular fat accurately. Pigs on C and LP1 regimes did not differ significantly in composition during growth. However, pigs on the LP2 regime had significantly more fat (in carcass, internal and intra-muscular depots) and less muscle, from 85kg onwards. Although fat levels differed depending on diet regime (LP2>others), proportions of fat in different body depots were unaffected.