Profile of fiber types in muscles from wild pigs native to the United States

Histochemical and histological parameters of the longissimus (LD) and semitendinosus (dark and light portions) muscles from wild pigs native to Florida, USA, were investigated. All three fiber types were present in both muscles at varying proportions with typical (red fibers grouped in clumps and surrounded by white fibers) fiber arrangements for domestic porcine muscles (Cassens, 1971), contrary to the findings by Rahelic & Puac (1981), who examined the LD muscle of wild pigs native to Yugoslavia. These authors foud only βR fibers present in the LD muscle. In five of the six pigs in the present study, extremely and abnormally large fibers (giant fibers), possessing βR fiber characteristics, were observed. These giant fibers were found in both the LD and the semitendinosus (dark and light portions) and were not restricted to the periphery of the fasiculi. The presence of these giant fibers suggests some type of muscle myopathy syndrome in these pigs.     

COMPOSITION,WATER-HOLDING CAPACITY AND pH OF MUSCLES FROM PIGS SUPPLEMENTED WITH PORCINE SOMATOTROPIN (pSt)1

Eighteen pigs were injected with one of three levels of recombinant porcine somatotropin (pSt) and received no more injections 7 days before slaughter. Excised triceps brachii, psoas major, semimembranosus, semitendinosus and biceps femoris muscles were analyzed for crude fat, moisture and protein contents, pH and water-holding capacity, Generally, raw muscles from somatotropin-supplemented pigs contained less crude fat than did muscles from control animals. The crude fat content of the broiled triceps brachii and roasted biceps femoris decreased in response to somatotropin supplementation. Muscles from supplemented and unsupplemented pigs did not differ in cooked muscle moisture or protein contents, raw or cooked pH or raw muscle water holding capacity.     

Influence of Breed Type, Sex, Feeding Systems, and Muscle Bundle Size on Bovine Fiber Type Characteristics

Fiber type numbers, percentages and diameter were evaluated in two experiments. Experiment 1 contained Angus and Angus cross cattle consisting of 48 steers and 48 heifers with half of each sex fed grain while the other half were fed grain-on-grass. Experiment 2 contained 12 Angus and 12 Simmental cross steers slaughtered at four feeding system endpoints. Steers tended to have a higher percentage of βR and a lower percentage of αW fibers than heifers; The percentage of βR fibers increased in the longissimus and semi-membranosus, while the αW fibers decreased. The percentage of αW fibers in the biceps femoris and semitendinosus muscles increased over the longer feeding period while the percentage βR tended to decrease. Breed appeared to have little effect on histological traits in the longissimus and semimembranosus muscles. Bundle size had no effect on fiber type diameter; however, in all muscles there was a tendency for the βR population to increase as bundle size increased.     

Post-natal changes in some histochemical and enzymatic characteristics of three pig muscles

Post-natal changes in histoenzymatic and enzymatic characteristics were studied in porcine longissimus, psoas major and tibialis cranialis muscles. The experiment was carried out on thirty-five female large White pigs: fifteen were slaughtered between birth and 120 kg body weight (BW) and twenty at the market liveweight of 100 kg. The relative growth of each of the three muscles in relation to BW appeared to be monophasic, the allometric growth rates differed significantly between muscles: 1·21, 1·08 and 0·97, respectively. Myofibers were classified according to their contractile and metabolic properties as βR, αR and αW fibers. In the three muscles, the percentage of β fibers increased from birth up to 2 months of age and little change occurred thereafter. Glycolytic fibers were detectable only from about one month onwards. Their percentage then increased rapidly up to 30-50 kg BW to reach 60%, 30% and 12% in longissimus, psoas major and tibialis cranialis muscles, respectively. Thereafter, these values only changed slightly. This histoenzymatic differentiation led to the typical type grouping found in pigs. Throughout the period studied, the cross-sectional area of the myofibers increased with some differences according to fiber type and muscle. Lactate dehydrogenase (LDH) specific activity was similar in the three muscles at birth and then increased rapidly up to 4-5kg BW (15-20 days of age), although to a greater extent in the future glycolytic muscle (longissimus) This increase then abruptly slowed down. The period between 15 and 20 days of age corresponds to a critical stage already known in the rearing of pigs, i.e. growth rate, body composition and food intake. Changes in isocitrate dehydrogenase (ICDH) specific activity were much slighter and differed according to the muscle. There were close correlations between percentages of αW fibers and enzymatic kinetic measurements from one month onwards.     

Shortening and tenderness of pre-rigor heated beef: Part 2 - Effect of heating rate on muscles of electrically stimulated carcasses

This study was conducted to compare the effects of rapid and slow heating rates on muscles from electrically stimulated beef carcasses. Myofibrillar and cooking shortening and related changes were measured with physiograph recordings on pre-rigor M. triceps brachii strips suspended in paraffin oil during heating. Warner-Bratzler shear values were determined on pre-rigor and post-rigor M. triceps brachii samples heated at approximately the same rates at which muscle strips were heated (2°C/2 min and 2°C/12 min), on pre-rigor M. triceps brachii samples heated at 2°C/6 min, 2°C/9 min and 2°C/12 min and on pre-rigor and post-rigor M. triceps brachii and M. longissimus muscle heated similarly at 2°C/12 min. Rapid heating (2°C/2 min) of pre-rigor muscle produced more severe myofibrillar shortening that was complete at higher muscle temperature than slow heating (2°C/12 min). Slow heating, in contrast to rapid heating, resulted in a cooked product of lower shear value in both the pre-rigor and post-rigor states. The slower the heating rate of the pre-rigor M. triceps brachii, the more tender was the product. Heating at a rate of 2°C/12 min produced acceptable tenderness in both the pre-rigor M. longissimus and M. triceps brachii muscles but even greater tenderness when both muscles were heated in the post-rigor state. The tenderizing action of severe muscle shortening could not be induced in electrically stimulated muscle.     

Histochemical properties of fibre types in muscles of wild and domestic pigs and the effect of growth rate on muscle fibre properties

This study reports the results of a comparison of the histochemical properties of various types of porcine muscles in wild and domestic pigs. In domestic pigs, the influence of growth rates on these properties were studied in five muscles: longissimus dorsi (LD), semimembranosus (SM), gluteus superficialis (GS), infra spinam (IS) and masseter (MAS). The growth rate was expressed as: (i) live weight (LW) at 165±2 days and (ii) daily LW gain from day 88 to day 165 (DG) on the experimental diet. LD, SM, GS and IS of wild pigs were found to contain a higher area percentage of oxidative type IIA fibres (type IIA%(area)) and a lower percentage area of glycolytic type IIB fibres (type IIB%(area)) than the same muscles of domestic pigs. The capillary density in the light muscles (LD, SM, GS) of wild pigs was twice that of domestic pigs, indicating higher oxidative capacity. In domestic pigs the cross sectional area of type IIB fibres (CSA(IIB)) was markedly larger than the cross sectional area of type I (CSA(I)) and IIA (CSA(IIA)) fibres. The average fibre cross sectional area (CSA(fibre)) was about the same in the muscles of wild and domestic pigs except in LD and SM, where the average fibre cross sectional area was approximately 25% smaller in wild pigs than in domestic pigs. This difference was caused by the large cross sectional area of type IIB fibres in the light muscles of domestic pigs. In the light muscles of domestic pigs, the cross sectional area of type IIA fibres increased most with increasing growth rate. Growth rate influences muscle fibre properties only in light muscles, not in dark muscles.     

Composition of Bovine Muscle Lipids at Various Carcass Locations

SUMMARY— Bovine intramuscular lipids extracted from the semitendinosus, triceps brachii and longissimus dorsi muscles were fractionated into phospholipids and neutral fats by silicic acid column chromatography. In spite of the wide range in total fat content at each location, phospholipids were present in all three muscles at a level of approximately 500 mg per 100 g of muscle tissue. This result, coupled with the lower total fat content of the semitendinosus as compared to the other two muscles, indicated a significantly higher percentage of phospholipid material in the total fat from the semitendinosus as compared to the triceps brachii or longissimus dorsi.
The fatty acids were identified in both lipid fractions using retention time data obtained on both a polar and a non-polar column. The identity of the unsaturated fatty acids was confirmed when their peaks did not appear on the chromatographs obtained from brominated samples. There was significantly more C14:0 in the longissimus dorsi neutral fat fractions than in the semitendinosus neutral fat fractions. In the phospholipids, there was significantly more C16:0 and significantly less C18:0 in the longissimus dorsi as compared to either the semitendinosus or triceps brachii. Although the two lipid fractions of the longissimus dorsi contained slightly higher percentages of total saturated fatty acids than the corresponding fractions in the other two muscles, the effects were not significant.     

Relationship of Fiber Type Composition to Marbling and Tenderness of Bovine Muscle

Beef carcasses (n = 65) were selected to range widely in marbling (moderately abundan: to practically devoid) and maturity (A, n = 25; B, n = 19; C, n = 6; D, n = 8; E, n = 7). Number, percent, area and mean diameter of β-red (βR), α-white (αW) and α-red (αR) muscle fibers were determined. Warner-Bratzler shear force values and taste panel tenderness ratings were also obtained. αW muscle fiber parameters were negatively correlated (P < 0.05) to marbling and tenderness ratings while αR and βR parameters were positively correlated (P < 0.05) to these quality attributes. The ratio of αW fiber area to βR and/or αR fiber area was correlated (P < 0.05) with marbling and tenderness. Regression analyses indicate that muscle fiber type composition is more highly related to marbling (marb) than it is to shear force value (SFV) or tenderness rating (TR) although all relationships were significant (P < 0.10). The relationship of these quality indicators to fiber type is greater within A maturity [marb, coefficient of determination (C.D.) = 65.09; SFV, C.D. = 65.09; SFV, C.D. = 28.85; TR, C.D. = 62.94] than for the entire population (murb, C.D. = 49.16; SFV, C.D. = 18.71; TR, C.D. = 30.47). It appears that the oxidative capacity of a muscle is related to marbling and tenderness and that muscle fiber type composition could possibly be used as a predictor of marbling potential.     

Chemical fat composition of muscles of the indigenous Nigerian pigs as influenced by age and sex

Seven selected muscles of 96 indigenous Nigeria (32 female, 32 castrated male and 32 intact male) pigs aged between birth and 504 days were analysed for chemical fat. Highly significant age effects were observed for the seven muscles. Statistically significant sex differences were observed for all the muscles except semitendinosus. Generally, fat values for muscles of intact male pigs were lower than for the other two sexes. While non-significant sex-age interactions were observed for biceps femoris, semitendinosus, semimembranosous and longissimus dorsi muscles, highly significant effects were observed for psoas major, triceps brachii and infraspinatus. Growth coefficients b derived from log-log regressions of intramuscular fat weight on body weight ranged from an average of 1·088 (R(2) = 0·956) for M. infraspinatus to 1·348 (R(2) = 0·934) for M. biceps femoris and from 0·604 (R(2) = 0·945) to 0·756 (R(2) = 0·941) when related to carcass fat. Average growth coefficients for fore limb muscles were less than for hind limb and spinal column muscles. Fat growth in other depots is reported for comparison with growth of intramuscular fat.     

The effects of quality grade, aging, and location within muscle on Warner-Bratzler shear force in beef muscles of locomotion

Aging patterns of nine muscles from the chuck and round from two quality classifications of beef: USDA Select and upper 2/3 of USDA Choice grade were determined. The following muscles were evaluated: infraspinatus, triceps brachii - lateral head, triceps brachii - long head, serratus ventralis, complexus, splenius, rhomboideus, vastus lateralis and rectus femoris. Muscles were divided into four portions, progressing from anterior to posterior or dorsal to ventral orientation to the carcass depending on muscle fiber orientation. One steak was removed from each portion and aged for 7, 14, 21, or 28 d postmortem, then Warner-Bratzler shear force (WBSF) analysis was conducted. Consistent aging recommendations can be given for all muscles studied, as there was no aging by muscle interaction. An aging by USDA grade interaction was noted (P<0.05). The upper 2/3 of USDA Choice need not be aged beyond 7 d. USDA Select should be aged at least 14 d. Steak location within muscle had an effect (P<0.05) on WBSF values in four muscles. These data indicate that fabrication and merchandizing decisions should be made on an individual muscle basis.     

Muscle fiber properties and thermal stability of intramuscular connective tissue in porcine M. semimembranosus

BACKGROUND: Strips can be easily peeled from raw destructured pork (M. semimembranosus, SM muscle) by hand but in normal meat these strips break. In general, destructured meat is pale in color. Porcine SM muscles have thick muscle fibers which could predispose them to destructuration. This study investigated whether the onset and peak temperatures of thermal shrinkage (T_o and T_p) of intramuscular connective tissue from SM muscles were associated with muscle fiber thickness, capillary density or extracellular space. We also investigated whether these muscle fiber properties of destructured muscles differed from those of normal muscles. RESULTS: The destructured and normal muscles were similar in muscle fiber cross‐sectional area, capillary density, extracellular space and sarcomere length. T_o correlated negatively with sarcomere length. The water content of differential scanning calorimetry samples consisting of intramuscular connective tissue was higher in destructured muscles than in normal muscles. CONCLUSION: Muscle fiber properties (muscle fiber cross‐sectional area and sarcomere length) and capillary density are similar in destructured and normal SM muscles. T_o and T_p of intramuscular connective tissue are similar in destructured and normal muscles. Muscle fiber properties show no association with the thermal shrinkage properties of intramuscular connective tissue. Copyright © 2009 Society of Chemical Industry     

An improved procedure for identifying fiber types in ovine muscles

An improved histochemical procedure has been developed for the identification of three muscle fiber types (βR, αR, αW) in two ovine muscles. This procedure can be used in lieu of the traditional reciprocal procedures of using an oxidative enzyme and ATPase to identify fiber types. The advantage of this simultaneous staining procedure is that it eliminates duplication of effort and time plus it distinguishes the αR (intermediate) fibers more clearly than the traditional methods. For best results, muscle samples must be evaluated within 2h of slaughtering the animal and care must be taken to monitor the pH at regular intervals. More research is needed to determine specific conditions, i.e. sample time, pH, enzyme activity, etc., before this method can be recommended as the most appropriate procedure for determining fiber type in muscles of other species.     

新疆褐牛不同部位牛肉肌纤维类型及品质差异研究

为了研究新疆褐牛不同部位牛肉肌纤维类型组成及品质差异,测定了冈上肌、冈下肌、臂三头肌、腰大肌、背最长肌、半腱肌、半膜肌和股二头肌的肌纤维特性和品质特性,并通过相关性分析研究了牛肉品质和肌纤维特性之间的相关性。结果显示腰大肌、背最长肌和股二头肌分别具有最高的Ⅰ型、ⅡA型和ⅡB型肌纤维比例,八个部位肉的肌纤维直径为ⅡB型>ⅡA型>Ⅰ型,且腰大肌三种肌纤维类型直径均小于其他部位。冈上肌具有较低的b*值,冈下肌具有较低的剪切力、蒸煮损失率;臂三头肌具有较高的剪切力,腰大肌具有较低的剪切力、硬度、胶着性和pH,较高的粘聚性和压力失水率;背最长肌具有较低的咀嚼性、回复性和弹性;半腱肌具有较低的压力失水率、粘聚性和回复性,较高的L*值;半膜肌具有较低的L*值和咀嚼性,股二头肌具有较高的弹性、胶着性和咀嚼性。Ⅰ型、ⅡA型和ⅡB型纤维面积、直径与剪切力、硬度和蒸煮损失显著正相关(p<0.05),与压力失水率显著负相关(p<0.01);Ⅰ型肌纤维比例与硬度、剪切力显著负相关(p<0.05),ⅡB型肌纤维比例与剪切力正相关。结果表明,肌肉部位显著影响牛肉品质,特别是嫩度,增加Ⅰ型肌纤维比例、减少ⅡB型肌纤维比例均有利于提高牛肉嫩度。     

THE EFFECTS OF DELAYED CHILLING AND ALTERED CARCASS SUSPENSION UPON BEEF MUSCLE: II. HISTOLOGICAL AND CHEMICAL PROPERTIES

A total of 60 bovine carcasses from “exotic”— crossbred heifers, 12 to 16 months of age with carcass weights of approximately 260 kg were utilized in two separate but related experiments to evaluate the effects of delayed chilling at 2 temperatures (13 and 22°C) for 12 or 24 h and altered carcass suspension on certain histological and chemical properties of beef muscle. Hip-free suspension (suspension by the os coxae from hooks inserted through the obturator foramen with the limbs hanging free) produced substantially greater alteration of the histological properties of the muscles evaluated than did delayed chilling. Such alterations resulted in longer semimembranosus (SM) and longissimus dorsi (LD) sarcomeres, shorter psoas major (PM) sarcomeres, smaller SM and LD muscle fiber diameters, larger PM muscle fiber diameters, fewer SM and LD wavy fibers, more PM wavy fibers, and shorter SM muscle fiber fragment lengths (P<0.05). Neither hip-free suspension nor delayed chilling produced consistent differences (P<0.05) in either the intramuscular collagen content, the heat solubility of the intramuscular collagen, or the histological properties of the intramuscular collagen fibers.     

Skeletal muscle cellularity and histochemistry in response to porcine somatotropin in finishing pigs

The effects of long-term application of recombinant porcine somatotropin (pST) on the development of muscle structure characteristics were examined in finishing pigs from about 120 to 200 days of age. Shot biopsy samples from the longissimus dorsi (longissimus) muscle of 60 Landrace barrows were taken at the initiation of treatment and again after 5 to 10 weeks treatment. The injection of 2 mg pST/d and 4 mg pST/d caused an intense hypertrophy of muscle fibres and resulted in 11% thicker muscle fibres at the end of treatment. In the course of fibre growth, dose-dependent differences occurred. The total muscle fibre number, calculated by muscle cross sectional area and fibre number per unit area of carcass samples, was not influenced. There was a tendency for more nuclei per fibre, whereas the nucleus-cytoplasm ratio seemed to be unchanged, Generally the composition of muscle fibre types (white, intermediate, red or αW, αR, βR) was not affected. In pST treatment groups, no more animals with giant fibres were found, nor were higher percentages of this structural anomaly in carcass muscle sections discovered.     

The characteristics of muscle fiber types of longissimus thoracis muscle and their influences on the quantity and quality of meat from Japanese Black steers

Forty-four Japanese Black fattening steers from four groups, produced in four districts and consisting of differing genetic backgrounds were slaughtered to examine the characteristic differences in muscle fiber types at the 6th thoracic vertebra of the M. longissimus thoracis (LT). The influence of percentage, diameter, and relative area of each muscle fiber type on the carcass characteristics and some quantity and quality traits of beef taken from LT, were also investigated. Significant differences in the characteristics of the muscle fiber types were observed among the four groups, except for muscle fiber diameter in the αR fiber, and the relative area of each αW fiber. For all steers, the average percentages and diameters of each muscle fiber type, βR, αR and αW were 26.8, 18.5 and 54.7% and 51.4, 50.6 and 52.4 μm, respectively. The relative area of each fiber type was similar to those of muscle fiber composition. αR Fiber content had significant negative correlations with marbling score (p<0.05), intramuscular fat content (p<0.05) and ultimate pH value (p<0.05). Significant correlations between the diameter of each fiber type, and the quantity or quality traits of the meat were not found, with the exception of red fiber types (βR and αR) and meat color a(?) values (p<0.05) which were positively correlated.     

Composition, solubility and gel properties of salt soluble proteins from two bovine muscle types

The composition, pH solubility profile and thermal gelation behavior of two bovine muscles, vastus intermedius (VI, predominately red fibers) and semimembranosus (SM, predominantly white fibers) were compared. VI had a higher fat content and pH and lower protein content than SM. Between pH 5.2 and 5.8, the salt soluble proteins (SSP) from SM were more soluble than those from VI at the same pH, whereas solubilities above pH 6.0 were similar. Properties of SSP gels were measured at pH 5.5 and 6.1, the ultimate pH for SM and VI, respectively. Water lost from the VI gels due to syneresis was about 3 times greater than that lost from SM gels. VI gels prepared at pH 5.5 were firmer (p<0.05) than at pH 6.1, whereas deformability of SM gels at pH 6.1 were greater (p<0.05) than at pH 5.5. No differences (p>0.05) were observed between the firmness or deformability of VI or SM gels when compared at the same pH. Results suggest that ultimate muscle pH and fiber type do influence the properties of bovine SSP gels, although the effect is not as great as that previously reported for poultry muscle proteins.     

Comparing the histochemical characteristics and meat quality traits of different pig breeds

The purpose of this study was to compare the muscle histochemical characteristics and meat quality traits between Berkshire, Landrace, Yorkshire, and crossbred pigs. A total of 594 pigs were evaluated. A clear difference between histochemical properties was observed from the results for fiber type composition. In Berkshire pigs, the area percentage of type I fibers was higher (P < 0.001) and that of type IIb fibers was lower (P < 0.05) than those of other breeds. The muscle pH_45min and pH_24h were significantly higher in Berkshire pigs. Drip loss and color parameters were significantly different between the breeds (P < 0.001). The Berkshire pigs, which showed the highest muscle pH and lowest drip loss and L^* values, contained a significantly higher percentage of type I fibers than the other breeds. By comparing the fiber type compositions of the different breeds, the results imply that the longissimus dorsi muscle of Berkshire pigs is more oxidative than that of other breeds. A high pH value in Berkshire pigs is due to a high percentage of type I fibers and a low percentage of type IIb fibers. Based on these results, we conclude that muscle fiber composition can explain in parts the variation of meat quality across and within breeds.     

Comparative study of the histochemical properties, collagen content and architecture of the skeletal muscles of wild boar crossbred pigs and commercial hybrid pigs

The histochemical properties, collagen content and architecture of Musculus longissimusthoracis (LT), Musculus pectoralis profundus (PP) and Musculus biceps femoris (BF) were compared in F(1) (half blood) and F(2) (quarter blood) wild boar crossbred pigs and commercial hybrid pigs, and Japanese wild pigs. F(1) pigs showed the lowest growth rate, followed by F(2) pigs. The most rapid growth was shown by the commercial pigs. The percentage weights of LT and PP muscle to body weight were larger in the wild boar crossbred pigs than commercial pigs. The muscles of the crossbred pigs contained type I and IIA myofibers at higher frequency and type IIB at lower frequency than the commercial pigs, except for LT muscle of F(2) pigs. The myofiber diameter in each type of muscle did not differ between pigs except for the smaller type IIA in BF muscle in commercial pigs. The total amount of intramuscular collagen was less in LT muscles than the others. More intramuscular collagen was found in the wild boar crossbred pigs than the commercial pigs in LT and PP muscles. With an increase of collagen content, the perimysial collagen architecture developed but not the endomysial architecture. Traits characteristic of the crossbred pigs seem to be inherited from the wild boar. Our results clarify that cross breeding with wild boar results in pigs with distinctive muscle characteristics in terms of histochemical properties, collagen content and architecture.     

A Sensory Panel and Chemical Analysis of Certain Beef Chuck Muscles

Sensory panel and Warner-Bratzler Shear (WBS) values of nine muscles (biceps brachii, complexus, deep pectoral, infraspinatus, longissimus, rhomboideus, serratus ventralis, supraspinatus and triceps brachii) from the beef chuck. The deep pectoral, infraspinatus and rhomboideus were used to determine myofibril fragmentation index (MFI), and the infraspinatus and rhomboideus were used to study myofibrillar protein degradation. The infraspinatus was scored the most tender and palatable, and the rhomboideus was scored least tender and palatable. Greater protein degradation differences were observed in myofibrils isolated from the infraspinatus muscle than in those from the rhomboideus for the proteins titin, nebulin and troponin-T.