The role of intramuscular connective tissue in meat texture

The structure, composition and amount of intramuscular connective tissue (IMCT) vary tremendously between muscles, species and breeds, and certainly contribute to meat texture. With animal growth, collagen crosslinks become more stable, and the structural integrity of IMCT increases. These changes increase the mechanical properties of IMCT, contributing to the toughening of meat. Intramuscular fat deposits, mainly in the perimysium between muscle fiber bundles, result in marbling. This causes the remodeling of IMCT structures and reduces the mechanical strength of IMCT, contributing to the tenderization of beef. The IMCT has been thought to be rather immutable compared to myofibrils during postmortem ageing of meat. However, recent studies have shown the disintegration of IMCT during postmortem ageing of meat and its relationship to tenderization of raw meat, although its contribution to cooked meat is still controversial. Given the large influence of IMCT on meat texture, further elucidations of molecular mechanisms which change the structural integrity of IMCT during chronological ageing of animals and postmortem ageing of meat are needed.     

滩羊饲料与肌肉中氨基酸含量相关性的研究

试验测定饲料中各种氨基酸含量和用饲料饲喂后成年滩羊肉和羔羊肉中氨基酸含量.结果表明,羔羊饲料中的天门冬氨酸、苏氨酸、丝氨酸、谷氨酸、胱氨酸、亮氨酸、酪氨酸等13种氨基酸和肌肉中相应的氨基酸呈强相关关系;对于成年滩羊而言,除酪氨酸外所喂饲料和饲喂后肌肉中氨基酸的相关性均为弱相关.     

牛CAPN3基因多态性及与肉质性状相关性分析

以中国草原红牛、西门塔尔牛、利木赞牛、天一冈山黑牛为试验对象,利用PCR-SSCP结合测序的方法进行SNPs检测,并采用SPSS软件分析CAPN3基因的遗传多态性与肉质性状的关系。结果表明,仅在草原红牛及天一冈山黑牛中发现第46 414处（NC_007308）发生G→T的突变,且发生G→T突变的位点所对应不同基因型的个体,其大理石花纹、失水率、滴水损失和剪切力这些肉质性状存在显著差异,而西门塔尔牛和利木赞牛中未发现此突变。     

Different levels of selenomethionine on the meat quality and selenium deposition in tissue of finishing pigs

The aim of the study was to verify the influence of selenomethionine (SM) supplementation on performance, carcass yield, characteristics of meat quality and Se tissue deposition of finishing pigs. A total of 128 hybrid pigs with an average weight of 76 kg were distributed in randomized blocks according to body weight in eight treatments and eight replicates. The experimental treatments were two Se levels from sodium selenite‐SS (0.3 and 0.6 ppm), four Se levels from SM (0.3, 0.4, 0.5 and 0.6 ppm) and two combinations of SS with SM (SS 0.15 + SM 0.15 ppm and SS 0.3 + SM 0.3 ppm) providing 0.3 and 0.6 ppm Se in the diet respectively. The feeds were based on corn and soya bean meal. After 30 days on test, were analysed the performance indices and the pigs were slaughtered at commercial slaughterhouse. The cold carcass yield, the physicochemical characteristics of the loin meat and the Se content in muscle and liver were evaluated. There was no significant difference in performance indices (p > .05); however, there was a linear effect on the increase in pig carcass yield by increasing SM (p < .05). The use of SM solely or combined with SS provided higher Se deposition in muscle compared to SS (p < .05). The highest Se deposition in muscle occurred for SM at 0.4 ppm (p < .05). The SS provided higher Se deposition in liver (p < .05). The SM presented best results for meat quality compared to other sources (p < .05). The level of 0.4 ppm Se promoted the best results for the indices of yellow, luminosity, cooking loss and pH (p < .05). The use of SM at any level promotes higher oxidation stability of pig meat (p < .05). The supplementation of SM at a level of 0.4 ppm promotes better physicochemical characteristics and higher Se deposition on swine meat.     

Genetic evaluation of meat quality traits and their correlation with growth and carcase composition in Japanese quail

1. Estimates of heritability, genetic and phenotypic correlations of performance and meat quality traits were obtained in a population of Japanese quail using restricted maximum likelihood (REML) procedures.

2. The heritability estimates for body weight (BW) traits ranged from 0·15 at hatch to 0·42 at six weeks. For carcase composition traits, heritability estimates ranged from 0·12 for carcase yield to 0·26 for abdominal fat yield and for meat quality traits they ranged from 0·18 for drip loss to 0·54 for yellowness of the meat.

3. Negative genetic correlations were found between BW and carcase traits with ultimate pH and drip loss ranging from ?0·01 (BW at hatch) to ?0·40 (skin yield). Redness and yellowness showed negative genetic correlations with BW and carcase traits, whereas the genetic correlations with lightness were positive (from 0·04 to 0·43).

4. Shear force and cooking loss showed positive genetic correlations with carcase, breast, abdominal and skin yield.

5. In conclusion, meat quality traits have the potential to be improved through genetic selection but selection for higher BW and carcase composition may reduce the meat quality of Japanese quail through reducing redness, ultimate pH and intramuscular fat and increasing lightness, shear force and cooking loss of the meat.     

Meat Science and Muscle Biology Symposium: manipulating meat tenderness by increasing the turnover of intramuscular connective tissue

Controlled reduction of the connective tissue contribution to cooked meat toughness is an objective that would have considerable financial impact in terms of added product value. The amount of intramuscular connective tissue in a muscle appears connected to its in vivo function, so reduction of the overall connective tissue content is not thought to be a viable target. However, manipulation of the state of maturity of the collagenous component is a biologically viable target; by increasing connective tissue turnover, less mature structures can be produced that are functional in vivo but more easily broken down on cooking at temperatures above 60°C, thus improving cooked meat tenderness. Recent work using cell culture models of fibroblasts derived from muscle and myoblasts has identified a range of factors that alter the activity of the principal enzymes responsible for connective tissue turnover, the matrix metalloproteinases (MMP). Fibroblasts cultured from 3 different skeletal muscles from the same animal show different cell proliferation and MMP activity, which may relate to the different connective tissue content and architecture in functionally different muscles. Expression of MMP by fibroblasts is increased by vitamins that can counter the negative effects of oxidative stress on new collagen synthesis. Preliminary work using in situ zymography of myotubes in culture also indicates increased MMP activity in the presence of epinephrine and reactive oxidative species. Comparison of the relative changes in MMP expression from muscle cells vs. fibroblasts shows that myoblasts are more responsive to a range of stimuli. Muscle cells are likely to produce more of the total MMP in muscle tissue as a whole, and the expression of latent forms of the enzymes (i.e., pro-MMP) may vary between oxidative and glycolytic muscle fibers within the same muscle. The implication is that the different muscle fiber composition of different muscles eaten as meat may influence the potential for manipulation of their connective tissue turnover.     

不同屠宰体重商品猪胴体性能、肉品质及相关关系研究

测定了体重70～140 kg阶段120头商品猪的胴体品质和肉质特性,分析了商品猪胴体性能、肉质性状随体重的变化规律及相关程度,为确定适宜上市屠宰体重提供依据。结果表明:70～100 kg体重阶段,随体重增大,平均背膘厚、眼肌面积、皮脂率、肉色和大理石纹显著升高,后腿比例、瘦肉率、骨骼率、L和b值显著降低。胴体和肉质性状间相关程度有强有弱,相关系数有正有负。相同性状间有较强的正相关,相反性状间有较强的负相关。在70～140 kg阶段,胴体重、胴体直长、胴体斜长、眼肌面积、平均背膘厚、瘦肉率、皮脂率、骨骼率、肉色和L值与体重之间呈显著的回归关系,其他指标与体重间的线性相关不显著。     

Post mortem development of meat quality as related to changes in cytoskeletal proteins of chicken muscles

1. A procedure was developed to separate high and medium molecular weight myofibrillar proteins from chicken muscular tissue with a high resolution by flat bed sodium-dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and subsequent detection by either a general protein stain or Western blotting. These procedures were used to analyse the degradation process of cytoskeletal proteins in chicken breast and leg muscles during meat ageing. 2. This study demonstrates the degradation of all the examined cytoskeletal proteins: titin, nebulin and desmin as well as vinculin, a protein component of the costamere structure. All the examined proteins were found to be degraded during ageing of chicken breast and leg muscles. 3. Degradation of titin, nebulin and desmin started at 3 h post mortem in breast muscle. Intact titin and nebulin disappeared within 1 d. Intact desmin and vinculin were not detectable after 3 d post mortem. In leg muscle, the degradation process of all the examined proteins evolved much more slowly than in breast chicken muscles. 4. The changes observed in shear force, myofibrillar fragmentation and cooking loss were related to changes in cytoskeletal proteins and used to identify marker proteins or degradation products for the purpose of monitoring the development of meat ageing. The ageing process was faster in breast muscle than in leg muscle. 5. Significant correlations were found between degradation processes of titin, nebulin, and desmin and shear force, as well as myofibril fragmentation index of breast and leg muscles.     

让“放心肉”真正端上百姓餐桌

[本刊讯]2009年8月1日,新修订的<生猪屠宰管理条例>(以下简称<条例>)实施一周年.一年来,商务部先后组织召开了全国贯彻<条例>电视电话会议、全国生猪屠宰管理工作会议,部署贯彻落实<条例>,全面加强生猪屠宰管理.     

Feed added curcumin with increased solubility on plasma lipoprotein,meat quality,and fat content in broiler chicks

Tropical Animal Health and Production - The objective of this research was to investigate the effect of dietary supplementation of curcumin with increased solubility (CS: 0, 0.2, 0.4, 0.6, and 0.8%...     

不同肉质改良剂在肉猪肥育阶段的试验效果

随着国民经济发展和人民生活水平不断提高 ,人们对畜产品质量的要求也越来越高 ,对优质无公害放心肉的需求量越来越大 ,这种趋势将会持续增长。随着我国规模化养猪业的发展 ,在高产、高效的同时 ,如何生产符合国家有关标准和确保消费者健康安全的优质猪肉是养猪者所面临的重要问题。各科研单位开发研制的肉质改良剂 ,正是在国家安全生产猪肉的有关政策法规基础上生产出的高科技产品 ,对发展安全、高效、优质的放心肉和促进养猪业可持续发展都具有重要的现实意义。肉质改良剂具有促进生长、降低料耗、提高肉的持水性和改善肉色、提高饲料利用…     

Effects of florfenicol injection on the meat characteristics of the cervical muscles in cattle

OBJECTIVE: To determine the effects of florfenicol injection on the meat characteristics of the cervical muscles in cattle. ANIMALS: 100 steers (mean weight, 380 kg). PROCEDURE: In 50 calves, florfenicol (25 ml, twice) was injected into the cervical muscles of 1 side of the neck, and saline (0.9% NaCI) solution (25 ml, twice) was injected into the cervical muscles of the other side of the neck. In the remaining 50 calves, florfenicol was injected into the cervical muscles of 1 side of the neck, and nothing was injected into the cervical muscles of the other side of the neck. Animals were slaughtered 132 days later, and samples of the cervical muscles were submitted for histologic evaluation and measurement of shear forces. RESULTS: 2 injection sites used in the present study had extensive lesions, and both of these were sites where florfenicol had been injected. However, histologic scores for the florfenicol injection sites were not significantly different from scores for the contralateral saline solution injection sites and uninjected control sites. In addition, shear force values were not significantly different between sites in which florfenicol had been injected and the contralateral sites. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that few reactions should be expected with injection of florfenicol into the cervical muscles in steers and that reactions that do occur will consist mainly of fibrosis and infiltration of adipose tissue. However, shear force values, a measure of tenderness of the meat, should not be affected.     

The effects of soybean selenium proteinate on tissue selenium and meat quality traits in finishing pigs

The purpose of the present study was to evaluate the effects of soybean selenium proteinate on Se tissue retention and meat quality in pigs. In group A (n = 11) the mixtures were supplemented with soybean selenium proteinate, in group B (n = 11) with sodium selenite and in group C (n = 11) with Se-enriched yeast (0.3 mg Se per kg in all groups). The use of soybean selenium proteinate resulted in lower retention of Se in tissues (liver, heart, muscle) compared to Se-enriched yeast. Selenium concentrations in tissues achieved by soybean selenium proteinate and sodium selenite were comparable. No differences in serum Se, serum GSH-Px and meat quality traits were found among the groups.     

Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on selenium tissue distribution and meat quality in beef cattle

The objective was to determine the concentration of total Se and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in postmortem tissues of beef cattle offered diets containing graded additions of selenized enriched yeast (SY; Saccharomyces cerevisiae CNCM I-3060) or sodium selenite (SS). Oxidative stability and tissue glutathione peroxidase (GSH-Px) activity of edible muscle tissue were assessed 10 d postmortem. Thirty-two beef cattle were offered, for a period of 112 d, a total mixed ration that had been supplemented with SY (0, 0.15, or 0.35 mg of Se/kg of DM) or SS (0.15 mg of Se/kg of DM). At enrollment (0 d) and at 28, 56, 84, and 112 d following enrollment, blood samples were taken for Se and Se species determination, as well as whole blood GSH-Px activity. At the end of the study beef cattle were killed and samples of heart, liver, kidney, and skeletal muscle (LM and psoas major) were retained for Se and Se species determination. Tissue GSH-Px activity and thiobarbituric acid reactive substances were determined in skeletal muscle tissue (LM only). The incorporation into the diet of ascending concentrations of Se as SY increased whole blood total Se and the proportion of total Se comprised as SeMet, as well as GSH-Px activity. There was also a dose-dependent response to the graded addition of SY on total Se and proportion of total Se as SeMet in all tissues and GSH-Px activity in skeletal muscle tissue. Furthermore, total Se concentration of whole blood and tissues was greater in those animals offered SY when compared with those receiving a comparable dose of SS, indicating an improvement in Se availability and tissue Se retention. Likewise, GSH-Px activity in whole blood and LM was greater in those animals offered SY when compared with those receiving a comparable dose of SS. However, these increases in tissue total Se and GSH-Px activity appeared to have little or no effect in meat oxidative stability.     

波德代杂种一代羊肉品质特性研究

选取 7月龄的当地土种公羔和羯羔、波德代杂种公羔和羯羔各 5只 ,取肉样对肉品质进行分析。结果表明 :波德代杂种羔羊肉嫩度剪切值显著低于土种羔羊 (P <0 0 5 ) ;波德代杂种羯羔的熟肉率显著高于其它试验组 (P <0 0 5 ) ;土种羯羔的失水率极显著高于土种公羔和波德代羯羔 (P <0 0 1) ;波德代杂种羔羊肉色鲜红、肌间脂肪含量高、多汁性好 ,嫩度适宜 ,氨基酸种类齐全 ,营养成分全面 ,对当地土种羊在肉品质方面有良好的改良作用。     

Effects of nutritional level of concentrate‐based diets on meat quality and expression levels of genes related to meat quality in Hainan black goats

The present study investigated the effects of the nutritional levels of diets on meat quality and related gene expression in Hainan black goat. Twenty‐four goats were divided into six dietary treatments and were fed a concentrate‐based diet with two levels of crude protein (CP) (15% or 17%) and three levels of digestive energy (DE) (11.72, 12.55 or 13.39 MJ/kg DM) for 90 days. Goats fed the concentrate‐based diet with 17% CP had significantly (P < 0.05) higher average daily gains (ADG) and better feed conversion rates (FCR). The pH _24h value tended to decrease (P < 0.05) with increasing DE levels. The tenderness of Longissimus dorsi muscle (LD) and Semimembranosus muscle (SM) reduced with increasing CP levels (P < 0.05). With increasing DE levels, tenderness was increased (P < 0.05). The heart fatty acid‐binding protein (H‐FABP) mRNA expression levels in LD and SM increased with increasing DE levels (P < 0.05), but decreased with increasing CP levels (P < 0.05). The calpastatin (CAST) and μ‐calpain mRNA expressions levels in LD and SM were affected significantly (P < 0.05) by CP and DE levels in the diet. Therefore, the nutritional levels of diets affect meat quality and expression levels of genes associated with meat quality in Hainan black goats.