Muscle growth affects the metabolome of the pectoralis major muscle in red-winged tinamou (Rhynchotus rufescens).

The aim of the present study was to identify and quantify the metabolites (metabolome analysis) of the pectoralis major muscle in male red-winged tinamou (Rhynchotus rufescens) selected for growth traits. A selection index was developed for females [body weight (BW), chest circumference (CC), and thigh circumference (TC)] and males [BW, CC, TC, semen volume, and sperm concentration] in order to divide the animals into 2 experimental groups: selection group with a higher index (TinamouS) and commercial group with a lower index (TinamouC). Twenty male offspring of the 2 groups (TinamouS, n = 10; TinamouC, n = 10) were confined for 350 d. The birds were slaughtered and pectoralis major muscle samples were collected, subjected to polar and apolar metabolites extractions and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Analysis of the polar metabolomic profile identified 65 metabolites; 29 of them were differentially expressed between the experimental groups (P < 0.05). The TinamouS groups exhibited significantly higher concentrations (P < 0.05) of 25 metabolites, including anserine, aspartate, betaine, carnosine, creatine, glutamate, threonine, 3-methylhistidine, NAD+, pyruvate, and taurine. Significantly higher concentrations of cysteine, beta-alanine, lactose, and choline were observed in the TinamouC group (P < 0.05). The metabolites identified in the muscle provided information about the main metabolic pathways (higher impact value and P < 0.05), for example, phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; D-glutamine and D-glutamate metabolism; ß-alanine metabolism; glycine, serine and threonine metabolism; taurine and hypotaurine metabolism; histidine metabolism; phenylalanine metabolism. The NMR spectra of apolar fraction showed 8 classes of chemical compounds. The metabolome analysis shows that the selection index resulted in the upregulation of polyunsaturated fatty acids, unsaturated fatty acids, phosphocholines, phosphoethanolamines, triacylglycerols, and glycerophospholipids. The present study suggests that, despite few generations, the selection based on muscle growth traits promoted changes in metabolite concentrations in red-winged tinamou.

Identification of Novel Genes Associated with Fish Skeletal Muscle Adaptation during Fasting and Refeeding Based on a Meta-Analysis.

The regulation of the fish phenotype and muscle growth is influenced by fasting and refeeding periods, which occur in nature and are commonly applied in fish farming. However, the regulators associated with the muscle responses to these manipulations of food availability have not been fully characterized. We aimed to identify novel genes associated with fish skeletal muscle adaptation during fasting and refeeding based on a meta-analysis. Genes related to translational and proliferative machinery were investigated in pacus (Piaractus mesopotamicus) subjected to fasting (four and fifteen days) and refeeding (six hours, three and fifteen days). Our results showed that different fasting and refeeding periods modulate the expression of the genes mtor, rps27a, eef1a2, and cdkn1a. These alterations can indicate the possible protection of the muscle phenotype, in addition to adaptive responses that prioritize energy and substrate savings over cell division, a process regulated by ccnd1. Our study reveals the potential of meta-analysis for the identification of muscle growth regulators and provides new information on muscle responses to fasting and refeeding in fish that are of economic importance to aquaculture.

Amino Acids and IGF1 Regulation of Fish Muscle Growth Revealed by Transcriptome and microRNAome Integrative Analyses of Pacu (Piaractus mesopotamicus) Myotubes.

Amino acids (AA) and IGF1 have been demonstrated to play essential roles in protein synthesis and fish muscle growth. The myoblast cell culture is useful for studying muscle regulation, and omics data have contributed enormously to understanding its molecular biology. However, to our knowledge, no study has performed the large-scale sequencing of fish-cultured muscle cells stimulated with pro-growth signals. In this work, we obtained the transcriptome and microRNAome of pacu (Piaractus mesopotamicus)-cultured myotubes treated with AA or IGF1. We identified 1228 and 534 genes differentially expressed by AA and IGF1. An enrichment analysis showed that AA treatment induced chromosomal changes, mitosis, and muscle differentiation, while IGF1 modulated IGF/PI3K signaling, metabolic alteration, and matrix structure. In addition, potential molecular markers were similarly modulated by both treatments. Muscle-miRNAs (miR-1, -133, -206 and -499) were up-regulated, especially in AA samples, and we identified molecular networks with omics integration. Two pairs of genes and miRNAs demonstrated a high-level relationship, and involvement in myogenesis and muscle growth: marcksb and miR-29b in AA, and mmp14b and miR-338-5p in IGF1. Our work helps to elucidate fish muscle physiology and metabolism, highlights potential molecular markers, and creates a perspective for improvements in aquaculture and in in vitro meat production.

Feeding strategies impact animal growth and beef color and tenderness.

The impact of growth rate (GR) and finishing regime (FR) on growth and meat quality traits of Angus x Nellore crossbred steers, harvested at a constant body weight (530 ± 20 kg) or time on feed (140 days), was evaluated. Treatments were: 1) feedlot, high GR; 2) feedlot, low GR; 3) pasture, high GR and 4) pasture, low GR. Live body composition, carcass and meat quality traits were evaluated. High GR had greater impact on muscle and fat deposition in feedlot-finished, but not in pasture-finished animals. Feedlot animals had higher Longissimus muscle area, backfat thickness, meat luminosity and tenderness when compared to pasture groups. Moreover, pasture- and feedlot-finished animals with similar GR did not differ in the chromatic attributes of non-aged meat, regardless of endpoint. Thus, GR appeared to be the main factor driving beef chromatic parameters, while FR had a major impact on achromatic attributes and tenderness of meat.

Ascorbic Acid Supplementation Improves Skeletal Muscle Growth in Pacu (Piaractus mesopotamicus) Juveniles: In Vivo and In Vitro Studies.

In fish, fasting leads to loss of muscle mass. This condition triggers oxidative stress, and therefore, antioxidants can be an alternative to muscle recovery. We investigated the effects of antioxidant ascorbic acid (AA) on the morphology, antioxidant enzyme activity, and gene expression in the skeletal muscle of pacu (Piaractus mesopotamicus) following fasting, using in vitro and in vivo strategies. Isolated muscle cells of the pacu were subjected to 72 h of nutrient restriction, followed by 24 h of incubation with nutrients or nutrients and AA (200 µM). Fish were fasted for 15 days, followed by 6 h and 15 and 30 days of refeeding with 100, 200, and 400 mg/kg of AA supplementation. AA addition increased cell diameter and the expression of anabolic and cell proliferation genes in vitro. In vivo, 400 mg/kg of AA increased anabolic and proliferative genes expression at 6 h of refeeding, the fiber diameter and the expression of genes related to cell proliferation at 15 days, and the expression of catabolic and oxidative metabolism genes at 30 days. Catalase activity remained low in the higher supplementation group. In conclusion, AA directly affected the isolated muscle cells, and the higher AA supplementation positively influenced muscle growth after fasting.

What influence does resistance exercise order have on muscular strength gains and muscle hypertrophy? A systematic review and meta-analysis.

The objectives of this paper were to: (a) systematically review studies that explored the effects of exercise order (EO) on muscular strength and/or hypertrophy; (b) pool their results using a meta-analysis; and (c) provide recommendations for the prescription of EO in resistance training (RT) programmes. A literature search was performed in four databases. Studies were included if they explored the effects of EO on dynamic muscular strength and/or muscle hypertrophy. The meta-analysis was performed using a random-effects model with Hedges' g effect size (ES). The methodological quality of studies was appraised using the TESTEX checklist. Eleven good-to-excellent methodological quality studies were included in the review. When all strength tests, that is, both in multi-joint (MJ) and single-joint (SJ) exercises were considered, there was no difference between the EOs (ES = -0.11; p = 0.306). However, there was a difference between the MJ-to-SJ and SJ-to-MJ orders for strength gains in the MJ exercises, favouring starting the exercise session with MJ exercises (ES = 0.32; p = 0.034), and the strength gains in the SJ exercises, favouring starting the exercise session with SJ exercises (ES = -0.58; p = 0.032). No significant effect of EO was observed for hypertrophy combining site-specific and indirect measures (ES = 0.03; p = 0.862). In conclusion, increases in muscular strength are the largest in the exercises performed at the beginning of an exercise session. For muscle hypertrophy, our meta-analysis indicated that both MJ-to-SJ and SJ-to-MJ EOs may produce similar results.

Post-transcriptional silencing of myostatin-1 in the spotted rose snapper (Lutjanus guttatus) promotes muscle hypertrophy.

Muscle growth is regulated by several factors including the growth differentiation factor 8, known as myostatin, an inhibitor of myocyte differentiation and proliferation. Research on myostatin regulation was already conducted to improve growth rates in farmed animals, including aquatic species. To explore the effects of myostatin inactivation in a commercial marine fish (spotted rose snapper, Lutjanus guttatus) in vivo, we induced post-transcriptional silencing (knockdown) of myostatin-1 (mstn-1) by injecting dsiRNA directly into the muscle of juvenile fish (87 days post-hatch) using a commercial polymer as vehicle. Results show a significant decrease in mstn-1 expression starting at 2 days after injection and for up to 5 days. Knockdown of mstn-1 caused muscle fiber hypertrophy (but not hyperplasia); however, there were no significant changes in weight or length. Although still experimental, this study provides evidence that temporary knockdown of mstn-1 in a commercial marine fish in vivo promotes fiber hypertrophy and therefore could potentially help grow-out programmes in fish aquaculture.

Chronic stress inhibits growth and induces proteolytic mechanisms through two different nonoverlapping pathways in the skeletal muscle of a teleost fish.

Chronic stress detrimentally affects animal health and homeostasis, with somatic growth, and thus skeletal muscle, being particularly affected. A detailed understanding of the underlying endocrine and molecular mechanisms of how chronic stress affects skeletal muscle growth remains lacking. To address this issue, the present study assessed primary (plasma cortisol), secondary (key components of the GH/IGF system, muscular proteolytic pathways, and apoptosis), and tertiary (growth performance) stress responses in fine flounder ( Paralichthys adspersus) exposed to crowding chronic stress. Levels of plasma cortisol, glucocorticoid receptor 2 ( gr2), and its target genes ( klf15 and redd1) mRNA increased significantly only at 4 wk of crowding ( P < 0.05). The components of the GH/IGF system, including ligands, receptors, and their signaling pathways, were significantly downregulated at 7 wk of crowding ( P < 0.05). Interestingly, chronic stress upregulated the ubiquitin-proteasome pathway and the intrinsic apoptosis pathways at 4wk ( P < 0.01), whereas autophagy was only significantly activated at 7 wk ( P < 0.05), and meanwhile the ubiquitin-proteasome and the apoptosis pathways returned to control levels. Overall growth was inhibited in fish in the 7-wk chronic stress trial ( P < 0.05). In conclusion, chronic stress directly affects muscle growth and downregulates the GH/IGF system, an action through which muscular catabolic mechanisms are promoted by two different and nonoverlapping proteolytic pathways. These findings provide new information on molecular mechanisms involved in the negative effects that chronic stress has on muscle anabolic/catabolic signaling balance.

Upwelling-derived oceanographic conditions impact growth performance and growth-related gene expression in intertidal fish.

Growth is one of the main biological processes in aquatic organisms that is affected by environmental fluctuations such as upwelling (characterized by food-rich waters). In fish, growth is directly related with skeletal muscle increase; which represents the largest tissue of body mass. However, the effects of upwelling on growth, at the physiological and molecular level, are unknown. This study used Girella laevifrons (one of the most abundant intertidal fish in Eastern South Pacific) as a biological model, considering animals from upwelling (U) and non-upwelling (NU) areas. Here, we evaluated the effect of nutritional composition and food availability on growth performance and expression of key growth-related genes (insulin-kike growth factor 1 (igf1) and myosin heavy-chain (myhc)) and atrophy-related genes (muscle ring-finger 1 (murf1), F-box only protein 32 (atrogin-1) and BCL2/adenovirus E1B 19kDa-interacting protein 3 (bnip3)). We reported that, among zones, U fish displayed higher growth performance in response to nutritional composition, specifically between protein- and fiber-rich diets (~1g). We also found in NU fish that atrophy-related genes were upregulated with fiber-rich diet and during fasting (~2-fold at minimum respect U). In conclusion, our results suggest that the growth potential of upwelling fish may be a consequence of differential muscle gene expression. Our data provide a preliminary approach contributing on how upwelling influence fish growth at the physiological and molecular levels. Future studies are required to gain further knowledge about molecular differences between U and NU animals, as well as the possible applications of this knowledge in the aquaculture industry.

Whey protein increases muscle weight gain through inhibition of oxidative effects induced by resistance exercise in rats.

Whey protein (WP) is known for its nutritional value and antioxidant properties. The aim of this study was to evaluate whether the antioxidant properties of WP could contribute to muscle weight gain in response to resistance exercise (RE). We hypothesized that WP ingestion could increase muscle weight gain in rats subjected to an RE program, through inhibition of oxidative effects induced by high-intensity RE. Thirty-two male Fischer rats were randomly assigned to control sedentary, control exercised, WP sedentary, and WP exercised groups (n=8/group). The RE consisted of inducing the rats to perform sets of jumps for 8 weeks. Body and muscle weight gains, muscle glutathione content, histopathology, muscle antioxidant enzyme activities, and gene expression were evaluated. Body and muscle weight gains of exercised rats fed WP were higher than those of control exercised rats. Concomitantly, RE induced an increase in phagocyte infiltration, protein oxidation, and down-regulation of glutathione peroxidase and gamma-glutamylcysteine synthetase messenger RNA expression in gastrocnemius muscle (P<.05), effects that were inhibited by WP ingestion. Cytosolic superoxide dismutase and catalase messenger RNA expression were reduced only by RE (P<.05), and muscle glutathione content was increased only by WP (P<.05) with no significant interaction observed (P>.05). These findings suggest that differences in body and muscle weight gain in exercised rats fed control or WP diets were mediated, in part, by the antioxidant properties of WP, and indicate that when associated with RE, WP represents a nutritional aid to support muscle growth.

The role of matrix metalloproteinases in muscle and adipose tissue development and meat quality: A review.

Matrix metalloproteinases (MMPs) are a group of enzymes that degrade extracellular matrix components but are also important signaling molecules that regulate many biological processes including muscle, adipose and connective tissue development. Most recently it has been discovered that MMPs act as intracellular signaling molecules inducing gene expression and altering related proteins in the nucleus. Several single nucleotide polymorphisms of MMPs and their inhibitors are known to exist and most of the research on MMPs to date has focused on their activity in relation to human health and disease. Nevertheless there is a growing body of evidence identifying important roles of MMPs as regulators of myogenesis, fibrogenesis and adipogenesis. The aim of this review is to highlight the currently known functions of the MMPs that have a direct bearing on the deposition of meat components and their relationship with meat quality. Some central pathways by which these enzymes can affect the tenderness, the amount and type of fatty acids are highlighted.

Morphological and morphometric analysis of skeletal muscle between male and female young adult Colossoma macropomum (Characiformes: Serrasalmidae)

This study aimed to evaluate muscle organization in tambaqui in order to describe the muscle growth process. We analyzed the morphometric pattern of fibers from white muscle of young-adults (300 days) by smaller diameter. The organization of white muscle exhibited a typical morphological pattern found in other fish species. Heavier animals showed higher frequency of larger diameter fibers (>50 m ) and smaller animals had higher frequency of smaller diameter fibers ( 20 m ) (P =0.005). However, both animals showed the same frequency of intermediate diameter fibers (20-50 m ). Body weight showed a positive correlation with muscle diameter fiber (r=0.45), being 20-50 m the diameters that contributed the most to animal weight (P 0.0001). A weak correlation between fiber diameter and animal sex was observed (r=0.2). Females showed higher frequency of large fiber diameters (>50 m ) than males. However, there was no difference between body weight and sex (P =0.8). Our results suggest that muscle growth is by hypertrophy and hyperplasia due to a mosaic appearance from different diameters fibers, which is characteristic of large size fish species.(AU)

O objetivo deste trabalho foi avaliar a organização muscular em tambaqui, a fim de descrever o processo de crescimento muscular. Foi analisado o padrão morfométrico das fibras do músculo branco de animais com 300 dias de idade usando o método de diâmetro menor. O músculo branco apresentou uma organização morfológica padrão encontrado em peixes. Animais de maior peso apresentaram maior frequência de fibras de maior diâmetro (> 50 m ) e os animais de menor peso apresentaram maior frequência de fibras de menor diâmetro ( 20 m ) (P = 0,005). Entretanto, ambos os animais, com maior e menor peso, apresentaram frequências semelhantes de fibras de diâmetro intermediário (20-50 m ). O parâmetro peso corporal mostrou correlação positiva com o diâmetro da fibra muscular (r = 0,45), sendo as fibras de diâmetro intermediários (20-50 m ) que mais contribuíram para o peso do animal (P 0,0001). Fêmeas apresentaram maior frequência de fibras de maior diâmetro (>50 m ) que machos. Observou-se uma fraca correlação entre o diâmetro da fibra e o sexo dos animais (r = 0,2). Apesar de fraca, a correlação estimada é corroborada pela fibras de grandes diâmetros (> 50 m ) serem mais frequente nas fêmeas que nos machos. No entanto, não houve diferença entre o peso corporal dos animais aos 300 dias de idade e sexo (P = 0,8). Os resultados encontrados sugerem que o crescimento muscular ocorre por hipertrofia e hiperplasia, caracterizado pela aparência em mosaico de fibras de diferentes diâmetros, característico de peixes de grande tamanho.(AU)

Morphological and morphometric analysis of skeletal muscle between male and female young adult Colossoma macropomum (Characiformes: Serrasalmidae)

This study aimed to evaluate muscle organization in tambaqui in order to describe the muscle growth process. We analyzed the morphometric pattern of fibers from white muscle of young-adults (300 days) by smaller diameter. The organization of white muscle exhibited a typical morphological pattern found in other fish species. Heavier animals showed higher frequency of larger diameter fibers (>50 m ) and smaller animals had higher frequency of smaller diameter fibers ( 20 m ) (P =0.005). However, both animals showed the same frequency of intermediate diameter fibers (20-50 m ). Body weight showed a positive correlation with muscle diameter fiber (r=0.45), being 20-50 m the diameters that contributed the most to animal weight (P 0.0001). A weak correlation between fiber diameter and animal sex was observed (r=0.2). Females showed higher frequency of large fiber diameters (>50 m ) than males. However, there was no difference between body weight and sex (P =0.8). Our results suggest that muscle growth is by hypertrophy and hyperplasia due to a mosaic appearance from different diameters fibers, which is characteristic of large size fish species.

O objetivo deste trabalho foi avaliar a organização muscular em tambaqui, a fim de descrever o processo de crescimento muscular. Foi analisado o padrão morfométrico das fibras do músculo branco de animais com 300 dias de idade usando o método de diâmetro menor. O músculo branco apresentou uma organização morfológica padrão encontrado em peixes. Animais de maior peso apresentaram maior frequência de fibras de maior diâmetro (> 50 m ) e os animais de menor peso apresentaram maior frequência de fibras de menor diâmetro ( 20 m ) (P = 0,005). Entretanto, ambos os animais, com maior e menor peso, apresentaram frequências semelhantes de fibras de diâmetro intermediário (20-50 m ). O parâmetro peso corporal mostrou correlação positiva com o diâmetro da fibra muscular (r = 0,45), sendo as fibras de diâmetro intermediários (20-50 m ) que mais contribuíram para o peso do animal (P 0,0001). Fêmeas apresentaram maior frequência de fibras de maior diâmetro (>50 m ) que machos. Observou-se uma fraca correlação entre o diâmetro da fibra e o sexo dos animais (r = 0,2). Apesar de fraca, a correlação estimada é corroborada pela fibras de grandes diâmetros (> 50 m ) serem mais frequente nas fêmeas que nos machos. No entanto, não houve diferença entre o peso corporal dos animais aos 300 dias de idade e sexo (P = 0,8). Os resultados encontrados sugerem que o crescimento muscular ocorre por hipertrofia e hiperplasia, caracterizado pela aparência em mosaico de fibras de diferentes diâmetros, característico de peixes de grande tamanho.

Expression of myostatin in the spotted rose snapper Lutjanus guttatus during larval and juvenile development under cultured conditions.

In this study, the developmental expression pattern of myostatin (mstn) in the spotted rose snapper Lutjanus guttatus under culture conditions is presented. The full coding sequence of mstn from L. guttatus was isolated from muscle tissue, obtaining 1134 nucleotides which encode a peptide of 377 amino acids. The phylogenetic analysis indicated that this sequence corresponds to mstn-1. mstn expression was detected in embryonic stages, and maintained at low levels until 28 days post-hatch, when it showed a significant increase, coinciding with the onset of metamorphosis. After that, expression was fluctuating, coinciding probably with periods of rapid and slow muscle growth or individual growth rates. mstn expression was also analysed by body mass with higher levels detected in smaller animals, irrespective of age. mstn was also expressed in other tissues from L. guttatus, presenting higher levels in brain, eye and gill. In brain for instance, two variants of mstn were isolated, both coding sequences were identical to muscle, except that one of them contained a 75 nucleotide deletion in exon 1, maintaining the reading frame but deleting two conserved cysteine residues. Phylogenetic analysis indicated that this brain variant was also mstn-1. The function of this variant is not clear and needs further investigation. These results indicate that mstn-1 participates in different physiological processes other than muscle growth in fishes.

Determinação, desenvolvimento do sexo e o seu efeito na deposição de tecidos em bovinos

Em todo o seu desenvolvimento, os bovinos passam por uma sequência complexa de eventos influenciados pelo sexo. Com o início da puberdade há um aumento na produção de hormônios, seguido da diferenciação sexual secundária. Surgem assim, os realces entre machos e as fêmeas, cujas características distintas contribuem para muitos aspectos de interesse zootécnico e econômico. Com este trabalho, expõe-se a necessidade de conhecer como o sexo atua ao longo do desenvolvimento animal, para que se possam elucidar de forma esquemática, os eventos que ocorrem desde a fecundação até a deposição de tecidos, tendo a condição sexual (macho ou fêmea) como fonte de variação. Ao final, pode-se notar a extrema importância de se trabalhar com as particularidades individuais de cada sexo, visando conduzir de melhor forma o crescimento animal, para alcançar a eficiência, a qualidade e a economia na produção.

Throughout its development, the cattle undergoes a complex sequence of events influenced by sex. With the start of puberty there is an increase in hormone production, followed by secondary sexual differentiation. Thus appear, highlights between males and females forming distinct characteristics that contribute to many aspects of economic and zootechnical interest. This work exposes the need of knowing how sex acts over the animal development, order to be able to elucidate schematically the events that occur from fertilization to the deposition of tissues, with the condition sex (male or female) as source of variation. In the end, it may be noted the extreme importance of working with the individual characteristics of each sex in order to conduct of better form animal growth to achieve efficiency, economy and quality in production.

Determinação, desenvolvimento do sexo e o seu efeito na deposição de tecidos em bovinos

Em todo o seu desenvolvimento, os bovinos passam por uma sequência complexa de eventos influenciados pelo sexo. Com o início da puberdade há um aumento na produção de hormônios, seguido da diferenciação sexual secundária. Surgem assim, os realces entre machos e as fêmeas, cujas características distintas contribuem para muitos aspectos de interesse zootécnico e econômico. Com este trabalho, expõe-se a necessidade de conhecer como o sexo atua ao longo do desenvolvimento animal, para que se possam elucidar de forma esquemática, os eventos que ocorrem desde a fecundação até a deposição de tecidos, tendo a condição sexual (macho ou fêmea) como fonte de variação. Ao final, pode-se notar a extrema importância de se trabalhar com as particularidades individuais de cada sexo, visando conduzir de melhor forma o crescimento animal, para alcançar a eficiência, a qualidade e a economia na produção. (AU)

Throughout its development, the cattle undergoes a complex sequence of events influenced by sex. With the start of puberty there is an increase in hormone production, followed by secondary sexual differentiation. Thus appear, highlights between males and females forming distinct characteristics that contribute to many aspects of economic and zootechnical interest. This work exposes the need of knowing how sex acts over the animal development, order to be able to elucidate schematically the events that occur from fertilization to the deposition of tissues, with the condition sex (male or female) as source of variation. In the end, it may be noted the extreme importance of working with the individual characteristics of each sex in order to conduct of better form animal growth to achieve efficiency, economy and quality in production. (AU)

Vitamin C prevents the effects of high rearing temperatures on the quality of broiler thigh meat1.

We investigated the effects of incubation temperatures and vitamin C injections into eggs (treatments: 37.5ºC, 39ºC, 39ºC+vitamin C) on resultant chick pectoralis major and sartorius muscle fiber hypertrophy, as well as their effects on the quality of breast and over-thigh meat of broilers reared under cold, control, or hot temperatures. Incubation at 39ºC increased the shear force and reduced meat redness in breast meat (P < 0.05). Vitamin C prevented these high temperature incubation effects [shear force (kgf cm(-2)): 37.5ºC = 2.34, 39ºC = 2.79, 39ºC+vitamin C = 2.44; redness: 37.5ºC = 2.64, 39ºC = 1.90, 39ºC+vitamin C = 2.30], but reduced water content (37.5ºC = 74.81%, 39ºC = 74.53%, 39ºC+vitamin C = 69.39%) (P < 0.05). Cold rearing temperatures increased breast meat redness (a*: cold = 2.78, control = 2.12, hot = 1.98), while hot rearing temperatures reduced the muscle fiber area (cold = 5.413 µm(2), control = 5.612 µm(2), hot = 4.448 µm(2)) (P < 0.05) without altering meat quality (P > 0.05). Hot rearing temperatures increased the cooking loss (cold = 30.10%, control = 33.66%, hot = 37.01%), shear force (cold = 3.05 kgf cm(-2), control = 3.43 kgf cm(-2), hot = 4.29 kgf cm(-2)) and redness (a*: cold = 4.63, control = 3.55, hot = 3.20) in the over-thigh meat of broilers from eggs incubated at 37.5ºC, increasing the area of muscle fibers, while cold rearing temperatures diminished cooking loss and shear force, reducing the muscle fiber area (P < 0.05). Incubation at 39ºC and 39ºC+vitamin C prevented the effects of hot and cold rearing temperatures, by diminishing and increasing the muscle fiber area, respectively.

Chemical and sensory meat characteristics of Nellore cattle (Bos indicus) finished with different levels of backfat thickness in the longissimus thoracis muscle / Características químicas e sensoriais da carne de bovinos Nelore (Bos indicus) terminados com diferentes espessuras de gordura subcutânea no Longissimus thoracis

The objective of this study was to evaluate the effect of backfat thickness (BFT) on the meat quality of feedlot-finished Nellore bulls (Bos indicus). Seventy-two animals were feedlot finished for about 100 days. For this study, 24 animals were sampled according to BFT in the longissimus thoracis muscle after slaughter: 12 animals with BFT up to 3.0 mm (class BFT-3) and 12 animals with BFT > 6.0 mm (class BFT-6). Chemical (myofibrillar fragmentation index, intramuscular fat content, and unsaturated and saturated fatty acids) and physical (cold carcass weight, rib eye area, and marbling score) characteristics of the meat were evaluated. Additionally, shear force and sensory characteristics (aroma, flavor, tenderness, chewiness, and juiciness) were analyzed. Marbling score and intramuscular fat content were considered low for the two BFT classes. The mean values of the characteristics studied did not differ (P>0.05) between BFT classes, except for fatty acids, with the observation of higher unsaturated fatty acid levels in the BFT-6 class. There was no difference (P>0.05) in sensory characteristics between BFT classes. The most consistent relationship was observed between the myofibrillar fragmentation index and tenderness, measured as shear force, in animals with greater BFT (BFT-6 class) compared to animals with lower BFT (BFT-3 class), suggesting possible tenderness problems in animals with a leaner carcass. The observation of a higher concentration of unsaturated fatty acids in animals with greater BFT suggests an increase in the sensory perception of meat, especially flavor...

O objetivo deste estudo foi avaliar o efeito da espessura de gordura subcutânea (EGS) na qualidade da carne de bovinos machos Nelore (Bos indicus), inteiros, terminados em confinamento. Setenta e dois animais foram terminados em confinamento por cerca de 100 dias. Para o presente estudo, 24 animais foram amostrados de acordo com a EGS obtida no longissimus thoracis, após o abate: 12 animais com EGS até 3,0 mm (classe EGS-3) e 12 animais com EGS maior que 6,0 mm (classe EGS-6). Foram avaliadas características químicas da carne (índice de fragmentação miofibrilar, conteúdo de lipídeos intramusculares e ácidos graxos insaturados e saturados), e características físicas da carcaça (peso da carcaça resfriada, área de olho de lombo e escore de marmorização). Adicionalmente, foram avaliadas em amostras maturadas por 21 dias, a força de cisalhamento e características sensoriais (aroma, sabor, maciez, mastigabilidade e suculência). Os valores de escore de marmorização e de conteúdo de lipídeos intramusculares foram considerados baixos para ambas as classes de EGS. As médias das características avaliadas não diferiram (P>0,05) entre as classes de EGS, com exceção dos ácidos graxos, que foi superior para o insaturado na classe EGS-6. As características sensoriais não diferiram (P>0,05) entre as classes de EGS. Foi verificado relação mais consistente entre índice de fragmentação miofibrilar e maciez, medida pela força de cisalhamento, em animais com maior EGS (classe EGS-6), comparativamente a animais com menor EGS (classe EGS-3), o que sugere possível problema de maciez em animais de carcaça mais magra. A observação de maior concentração de ácidos graxos insaturados em animais com maior EGS sugere aumento da percepção sensorial da carne, especialmente do sabor...

Chemical and sensory meat characteristics of Nellore cattle (Bos indicus) finished with different levels of backfat thickness in the longissimus thoracis muscle / Características químicas e sensoriais da carne de bovinos Nelore (Bos indicus) terminados com diferentes espessuras de gordura subcutânea no Longissimus thoracis

The objective of this study was to evaluate the effect of backfat thickness (BFT) on the meat quality of feedlot-finished Nellore bulls (Bos indicus). Seventy-two animals were feedlot finished for about 100 days. For this study, 24 animals were sampled according to BFT in the longissimus thoracis muscle after slaughter: 12 animals with BFT up to 3.0 mm (class BFT-3) and 12 animals with BFT > 6.0 mm (class BFT-6). Chemical (myofibrillar fragmentation index, intramuscular fat content, and unsaturated and saturated fatty acids) and physical (cold carcass weight, rib eye area, and marbling score) characteristics of the meat were evaluated. Additionally, shear force and sensory characteristics (aroma, flavor, tenderness, chewiness, and juiciness) were analyzed. Marbling score and intramuscular fat content were considered low for the two BFT classes. The mean values of the characteristics studied did not differ (P>0.05) between BFT classes, except for fatty acids, with the observation of higher unsaturated fatty acid levels in the BFT-6 class. There was no difference (P>0.05) in sensory characteristics between BFT classes. The most consistent relationship was observed between the myofibrillar fragmentation index and tenderness, measured as shear force, in animals with greater BFT (BFT-6 class) compared to animals with lower BFT (BFT-3 class), suggesting possible tenderness problems in animals with a leaner carcass. The observation of a higher concentration of unsaturated fatty acids in animals with greater BFT suggests an increase in the sensory perception of meat, especially flavor...(AU)

O objetivo deste estudo foi avaliar o efeito da espessura de gordura subcutânea (EGS) na qualidade da carne de bovinos machos Nelore (Bos indicus), inteiros, terminados em confinamento. Setenta e dois animais foram terminados em confinamento por cerca de 100 dias. Para o presente estudo, 24 animais foram amostrados de acordo com a EGS obtida no longissimus thoracis, após o abate: 12 animais com EGS até 3,0 mm (classe EGS-3) e 12 animais com EGS maior que 6,0 mm (classe EGS-6). Foram avaliadas características químicas da carne (índice de fragmentação miofibrilar, conteúdo de lipídeos intramusculares e ácidos graxos insaturados e saturados), e características físicas da carcaça (peso da carcaça resfriada, área de olho de lombo e escore de marmorização). Adicionalmente, foram avaliadas em amostras maturadas por 21 dias, a força de cisalhamento e características sensoriais (aroma, sabor, maciez, mastigabilidade e suculência). Os valores de escore de marmorização e de conteúdo de lipídeos intramusculares foram considerados baixos para ambas as classes de EGS. As médias das características avaliadas não diferiram (P>0,05) entre as classes de EGS, com exceção dos ácidos graxos, que foi superior para o insaturado na classe EGS-6. As características sensoriais não diferiram (P>0,05) entre as classes de EGS. Foi verificado relação mais consistente entre índice de fragmentação miofibrilar e maciez, medida pela força de cisalhamento, em animais com maior EGS (classe EGS-6), comparativamente a animais com menor EGS (classe EGS-3), o que sugere possível problema de maciez em animais de carcaça mais magra. A observação de maior concentração de ácidos graxos insaturados em animais com maior EGS sugere aumento da percepção sensorial da carne, especialmente do sabor...(AU)

Muscle free amino acid profiles are related to differences in skeletal muscle growth between single and twin ovine fetuses near term.

Twin sheep fetuses have reduced skeletal muscle weight near birth relative to singles as a result of restricted muscle hypertrophy. Intracellular free amino acids (FAA) are reported to regulate metabolic pathways which control muscle protein accretion, whereby reduced intracellular content of specific FAA may reduce their activation and therefore, muscle hypertrophy. The aim of this study was to determine whether differences in muscle weight between singleton and twin fetuses, under different maternal conditions is associated with reduced concentration of specific FAA. The FAA content in the semitendinosus muscle (ST) in singleton and twin fetuses (rank) at 140 days of gestation from heavy (H) or light (L) ewes fed ad libitum (A) or maintenance (M) level of nutrition was measured. Muscle weight was reduced in twin fetuses compared to singletons in all groups. Reduced concentrations of leucine, threonine and valine, but higher concentrations of methionine, ornithine, lysine and serine were found in twin fetuses compared to singletons. Maternal size and nutrition interaction with rank resulted in reduced glutamine in twins from HM-ewes (H-ewes under M nutrition) compared to their singleton counterparts. Maternal weight interaction with pregnancy rank reduced the concentration of arginine in twins, with a larger effect on H-ewes compared with L-ewes. Maternal size interaction with pregnancy rank resulted in twins from M-ewes to have lower alanine, while twins from A-ewes had lower aspartic acid concentration compared to singletons. The ST muscle weight was positively correlated only with arginine concentration after taking into account rank, size and nutrition. The present results indicate that reduced concentrations of specific intracellular FAA, such as arginine, leucine, valine, glutamine, which are known to play a role in muscle growth, could be acting as limiting factors for muscle hypertrophy in twin fetuses during late gestation. Ewe size and nutrition can influence the concentration of specific FAA in muscle and should be considered in any intervention plan to improve twin fetal muscle growth.