The effect of sex condition and growth implants on bovine muscle fiber characteristics

Steers, bulls and bulls implanted with Synovex-S or Ralgro were slaughtered at 12 and 16 months of age. With increasing animal age, the percentage of intermediate fibers decreased while the percentage of white fibers increased. The area of all fibers increased with increasing age. Bulls had a higher percentage of red fibers, larger red and intermediate fibers and a higher percentage area of red and intermediate fibers compared with steers. Implanted bulls were generally intermediate to intact bulls and steers in muscle fiber type characteristics. Carcass fat measurements and tenderness ratings were positively correlated to the percentage of white muscle fibers and negatively correlated to the percentage of intermediate fibers. Carcass characteristics and sensory properties of meat are discussed in relation to muscle fiber characteristics.     

Control of fresh meat quality through manipulation of muscle fiber characteristics

Variations of fresh meat quality exist because the quality traits are affected by various intrinsic and extrinsic factors. Because the meat quality is basically dependent on muscle fiber characteristics, numerous studies have reported the relationship between quality traits and fiber characteristics. Despite intensive research, the relationship is yet to be fully established, however, the present knowledge suggests several potential ways to manipulate muscle fiber characteristics to improve meat quality. The present paper reviews the definition of fresh meat quality, meat quality traits and variations of meat quality. Also, this review presents recent knowledge underlying the relationship between fresh meat quality traits and muscle fiber characteristics. Finally, the present work proposes several potential factors including breed, genotype, sex, hormone, growth performance, diet, muscle location, exercise and ambient temperature that can be used to manipulate muscle fiber characteristics and subsequently meat quality in animals.     

Carcass fat partitioning and meat quality of Alentejana and Barrosã young bulls fed high or low maize silage diets

This study assessed the effect of breed and diet on carcass composition, particularly fat partitioning, and meat quality in young bulls. An experiment with forty young bulls from two phylogenetically distant Portuguese bovine breeds, Alentejana and Barrosã, fed two diets with different maize silage to concentrate ratios, but isoenergetic and isonitrogenous, was carried out until the animals reached 18 months of age. In the longissimus lumborum muscle, Barrosã bulls fed the low silage diet had the highest intramuscular fat (IMF) content. Bulls fed the low silage diet also had the highest IMF content in the semitendinosus muscle. Diet determined the proportions of total visceral fat and individual fat depots. Under these experimental conditions, it was shown that the genetic background is a major determinant of carcass composition and meat quality, and that the dietary differences studied had limited effect on carcass composition.     

Effect of polymorphisms at the ghrelin gene locus on carcass, microstructure and physicochemical properties of longissimus lumborum muscle of Polish Landrace pigs

The influence of RFLP-BsrI polymorphisms at the ghrelin gene locus on carcass, meat quality parameters and muscle fiber characteristics of longissimus lumborum was studied in 168 barrows of the Polish Landrace breed. Analysis revealed a high frequency of the 1 allele (0.60) with the frequencies of the 11, 12 and 22 genotypes being 0.45, 0.30 and 0.25, respectively. The most favorable parameters of meat traits were characteristic of pigs with the 22 genotype, together with a higher carcass and loin weight and lower thermal loss compared to 12 heterozygotes. The highest fat content was found in pigs with the 11 genotype, which had the highest abdominal fat weight and mean backfat thickness. Meanwhile, the 12 heterozygotes were characterized by the largest loin eye areas, highest lightness (L*) and yellowness (b*) values, and lowest redness (a*) values, as well as the greatest hardness and chewiness and largest diameter of type IIB muscle fibers compared to the other genotypes.     

The effects of breed and halothane sensitivity on pig meat quality

The effects of halothane sensitivity and breed (Belgian Landrace BL and Landrace L), and their interactions on carcass and meat quality were analysed. Also the effect of breed (Pietrain P, BL, L, Large White LW and Duroc D) on carcass and meat quality was studied in a sample of 153 gilts. Each of the half-carcasses was cut and fully dissected to obtain lean percentage. The following measurements of meat quality were carried out: muscle pH, electrical conductivity (QM) and light scattering (POP). Muscle reflectance (GOFO value), muscle protein solubility (MPS) and intramuscular fat content were also determined. The results obtained in this study revealed the effect of halothane gene on all of the traits studied. The halothane-positive animals showed less fat thickness and more lean percentage in the carcass. The P and BL breeds had more lean percentage in the carcass and a better lean-to-bone ratio compared with L, LW and D. The L breed was intermediate. Stress sensitivity is an important factor affecting the inverse relationship between carcass quality and meat quality. Those breeds free of the halothane gene (LW and D) had the best meat quality. The L breed was in an intermediate position, but more similar to halothane-negative breeds. The Duroc breed had significantly higher intra-muscular fat (>2·0%), required for optimum fresh meat quality and for the production of Spanish dry-cured ham of high quality.     

Effects of tomato pomace supplementation on carcass characteristics and meat quality of fattening rabbits

The aim of this study was to determine how a feeding plan characterized by different levels of tomato pomace (TP) supplementation influences the carcass characteristics, the chemical, physical and sensorial characteristics of rabbit meat. 144 weaned crossbred rabbits were divided into three groups of 48 each. The first group was fed a basal diet without TP, while the other two groups were fed the basal diet after replacing part of the diet with TP at 3% and 6%, respectively. There was a significant difference between the experimental groups in terms of live and carcass weights. The meat of rabbits fed on a 6% TP diet exhibited higher yellowness (b*) and Chroma values when compared to others. The saturated fatty acid content in the longissimus dorsi muscle and perirenal fat decreased significantly with increasing TP inclusion, while polyunsaturated fatty acids increased. Furthermore, our results indicate that a diet integrated with 6% TP could influence positively the overall preference of cooked meat.     

Relationship of Carcass Weight to Muscle Fiber Characteristics and Pork Quality of Crossbred (Korean Native Black Pig × Landrace) F2 Pigs

A total of 168 carcasses of crossbred (Korean native black pig × Landrace) F₂ pigs were divided into four carcass weight groups (A, 70–79 kg; B, 80–89 kg; C, 90–99 kg; D, 100–109 kg). The influence of carcass weight on muscle fiber characteristics and meat quality traits of pork, from the longissimus dorsi, were investigated. Carcass traits such as loin-eye area and back-fat thickness were found to increase with increasing carcass weight. Fat content, sarcomere length, drip loss, and meat color values (L*, a*, and b*) also increased with increasing carcass weight. However, moisture content and Warner–Bratzler shear force decreased with increasing carcass weight. A decrease in the compositions of type I and IIA fibers and an increase in the composition of type IIB fibers were observed with increasing carcass weight. The heavier carcasses showed type I and IIB fibers of bigger size and a smaller size of type IIA fibers. Fiber number percentage and the diameter of type IIB showed a significant positive correlation with carcass weight, fat content, and lightness (p?<?0.05). Fiber diameter of type IIB was positively correlated with loin-eye area, but was negatively correlated with moisture content. However, muscle fiber characteristics had no correlation with back-fat thickness, ultimate pH, Warner–Bratzler shear force, and b* value. In conclusion, crossbred pig which has of high composition and size of type IIB has high lightness (L* value) and water-holding capacity (drip loss). Therefore, excessively high weight of carcass has influence on pale and exudative properties in pig because of muscle fiber characteristics, especially type IIB fiber.     

Performance, carcass and palatability characteristics of Longhorn and other types of cattle

Performance, carcass and palatability characteristics of Longhorn steers were compared with those of cattle currently popular in the United States-Hereford, Angus, Brahman, Holstein, two-breed crossbred (British beef breed crosses) and three-breed crossbred (1 4 dairy , 1 4 British beef and 1 2 European beef ) steers. Steers were fed roughage, then a growing diet (42 days), then a high energy (89% concentrate) diet (153 to 179 days by breed group) and slaughtered, individually, at USDA Choice finish or, failing that, after 186 days on the finishing diet. Data suggest that Longhorns, compared with types of cattle currently used: (1) are less desirable in physical appearance; (2) gain weight less rapidly, reaching the desired finish and slaughter weight as older animals; (3) convert feed to liveweight less efficiently; (4) deposit less subcutaneous fat, more internal fat, but essentially the same amount of intramuscular fat; (5) are as muscular (longissimus muscle area, estimated percentage of carcass muscle, muscle to bone ratio, muscle to fat ratio); (6) are as desirable in USDA quality grade and yield grade and (7) produce beef that is a palatable.     

Live weight and sex effects on carcass and meat quality of "Borrego terrincho-PDO" suckling lambs

Fifty seven suckling lambs (28 males and 29 females) of the Churra da Terra Quente breed were used to evaluate the effects of live weight and sex on carcass composition and meat quality traits. Lambs were slaughtered at three weight classes (<8 kg, 8–11 kg and >11 kg) according to “Borrego Terrincho–PDO” specifications. The left sides of the carcasses were totally dissected. The longissimus thoracis and lumborum muscle was used for meat quality determination. Dressing proportion and carcass fatness were not affected by weight class or sex. Muscle proportion was similar in all carcass joints for the three weight classes. The percentage of bone decreased at the higher weight class, while that of subcutaneous and intermuscular fat increased. Female lambs had higher muscle proportions and greater muscle/bone ratios in the carcass side than males. Muscle pH, colour, cooking losses and tenderness were not affected by gender and weight class. Female lambs and weight classes 8–11 kg and >11 kg had higher proportions of intramuscular fat.     

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.     

Effects of dietary olive and linseed oil on lipid composition, meat quality, sensory characteristics and muscle structure in pigs

The aim of this study was to alter the fatty acid composition of porcine tissue by accumulating essential fatty acids without adversely affecting carcass composition, muscle structure or meat eating quality. A total of 13 female and 12 castrated Pietrain×German Landrace pigs were fed a basal concentrate diet supplemented with 5% olive oil or 5% linseed oil during the growing-finishing period. Carcass composition and meat quality were not affected by the diet. Feeding linseed oil to pigs significantly increased the relative content of linolenic acid and long chain n-3 fatty acids in lipids of muscle, backfat and heart at the expense of arachidonic acid. Oleic acid was accumulated in muscle, backfat and heart lipids by feeding olive oil. The overall flavour of combined meat/backfat samples from castrates was negatively influenced by linseed oil supplementation compared to supplementation with olive oil. The oxidative stability of muscle lipids was lower in linseed oil-fed pigs compared to olive oil fed pigs. The greater cross section areas of the longissimus muscle of females were caused by an increased diameter of red, intermediate and white fibres.     

Prediction of carcass composition in the rabbit

Carcass composition of two synthetic rabbit breeds was predicted from retail cuts and external measurements by using regression equations. Breed R has a higher adult weight and reaches slaughter weight 1 week before breed V. Sixty rabbits of each breed were slaughtered when they (approximately) reached the Spanish commercial liveweight of 2kg. The carcasses were measured and retailed according to the norms of the World Rabbit Scientific Association. Rabbit carcass composition is well defined by meat percentage of the commercial carcass and ratio meat bone . External measurements on the carcass, retail cuts and meat of retail cuts or muscular masses are all bad predictors of carcass meat percentage or ratio meat bone (R(2) < 0.53). The ratio meat bone of the hind leg can give reasonable predictions for carcass meat percentage and meat bone ratio (R(2) = 0.60 and 0.69). Dissectible carcass fat weight and dissectible carcass fat percentage can be predicted by the perirenal fat weight (R(2) = 0.77 and 0.69). Fat depots had a low predictive power for fat percentage of the dissected meat in the half carcass.     

The Influence of Muscle Fiber Size on Tenderness in A-Maturity Heifers1

A total of 77 crossbred late-maturing or intermediate-maturing heifers were fed an 84% total digestible nutrient diet from 200 kg live-weight to slaughter at 433 kg. Carcass data and histochemical samples were obtained at 24 h postmortem, and shear and sensory panel evaluation samples were obtained from the longissimus dorsi muscle afier 7 ahys of aging at 2 to 3°C. Average fiber size was correlated (P< 0.01) to sensory panel tenderness and shear force requirements. Cross-sectional areas of white, intermediate and red fibers were also correlated (P< 0.01) to shear force requirements. Percentages of white, intermediate and red fibers were not consistently correlated to sensory tenderness or shear force. Evidently, the number of myofibrils per unit of mass was associated with meat tenderness. Research needs to be done to determine iffiber size has a causal relationship with tenderness or is a correlated response to other factors that dictate tenderness.     

The relationship between muscle fiber characteristics, postmortem metabolic rate, and meat quality of pig longissimus dorsi muscle

The aim of this study was to investigate the histochemical parameters of muscle fibers, and to estimate the correlation of muscle fiber characteristic to postmortem metabolic rate and meat quality traits in pigs. A total of 231 crossbred pigs were evaluated. Samples of the longissimus dorsi muscle were taken to evaluate the histochemical characteristics, postmortem metabolic rate and meat quality. Fiber type composition was mainly related to postmortem metabolic rate and meat quality traits among various muscle fiber characteristics. The percentage of type IIb fiber was negatively related to pH(45min) (r=-0.33) and positively to R-value (r=0.32). Drip loss was negatively related to fiber area percentages of type I and IIa (r=-0.25 and -0.26, respectively) and positively related to type IIb percentage (r=0.39). A similar tendency was found between lightness and fiber area percentage. In conclusion, increasing the percentage of type IIb fiber is related to increasing the postmortem metabolic rate, and is related to the deterioration of meat quality.     

Growth performance,carcass and meat quality of the Celta pig crossbred with Duroc and Landrance genotypes

The Celta pig is a native breed adapted to the north of Spain and extensive production system. The objective was to study the effects of sex and crossbreeding on carcass characteristics and meat quality. Samples were taken from longissimus dorsi muscle of 52 pigs of three different groups [Celta pure breed (C), Celta crossed with Landrace (C × L) and Celta crossed with Duroc (C × D)].     

Live weight and sex effects on carcass and meat quality of “Borrego terrincho–PDO” suckling lambs

Fifty seven suckling lambs (28 males and 29 females) of the Churra da Terra Quente breed were used to evaluate the effects of live weight and sex on carcass composition and meat quality traits. Lambs were slaughtered at three weight classes (<8 kg, 8–11 kg and >11 kg) according to “Borrego Terrincho–PDO” specifications. The left sides of the carcasses were totally dissected. The longissimus thoracis and lumborum muscle was used for meat quality determination. Dressing proportion and carcass fatness were not affected by weight class or sex. Muscle proportion was similar in all carcass joints for the three weight classes. The percentage of bone decreased at the higher weight class, while that of subcutaneous and intermuscular fat increased. Female lambs had higher muscle proportions and greater muscle/bone ratios in the carcass side than males. Muscle pH, colour, cooking losses and tenderness were not affected by gender and weight class. Female lambs and weight classes 8–11 kg and >11 kg had higher proportions of intramuscular fat.     

Carcass characteristics of suckling lambs protected by the PGI "Lechazo de Castilla y León" European quality label: Effect of breed, sex and carcass weight

In the Region of "Castilla y León" (Spain), as in other Mediterranean areas, fresh suckling lamb meat is regarded as having a high edible quality. The EU granted this product a Protected Geographical Indication (PGI) "Lechazo de Castilla y León" in 1999. In this study, several carcass characteristics of suckling lambs protected by this PGI were determined, while the effects of breed, sex, and carcass weight were studied. Some differences in carcass characteristics within the three PGI authorized breeds have been detected. Neither carcass weight nor conformation measurements were good predictors of the composition of the PGI protected suckling lamb carcasses. The best predictors were fatness and composition of the leg and loin tissues, although dissection of these joints is not feasible on a daily basis. Lastly, some differences, due to sex and weight were identified in conformation, fat percentage, jointing and joint composition. Differences were, however, rather small, due to the lambs' young age and low variation in carcass weight.     

不同饲养方式下苏尼特羊肌纤维组成和羊肉品质的比较研究

本研究以6月龄苏尼特羊背最长肌为试验对象,分析三种饲养方式（放牧、放牧+补饲和舍饲）屠宰性能和肉品质的差异,通过ATPase组化染色法、肌球蛋白重链（Myosin Heavy Chain,MyHC）分子分型法对肌纤维类型进行定性及定量划分,并测定肌肉代谢酶活力,探究不同饲养方式肉品质产生差异性的内在原因。结果表明:放牧组的屠宰性能指标（总增重量、净肉重量、净肉率、屠宰率、产肉率）与胴体品质指标（背膘厚、胴体重）显著低于舍饲组和放牧+补饲组（P<0.05）,放牧组的骨肉比显著高于舍饲组和放牧+补饲组（P<0.05）。放牧+补饲组和放牧组pH_{24 h}显著低于舍饲组（P<0.05）,放牧组剪切力值显著低于舍饲组（P<0.05）。放牧组和放牧+补饲组Ⅱb型肌纤维直径和面积比例显著低于舍饲组（P<0.05）,MyHCⅡb mRNA表达量显著低于舍饲组（P<0.05）。放牧组Ⅰ型、Ⅱa肌纤维直径和横截面积、乳酸脱氢酶（lactic dehydrogenase,LDH）活力均显著低于舍饲组（P<0.05）,舍饲组肌纤维密度、Ⅱa数量比例及面积比例、MyHCⅠmRNA表达量、苹果酸脱氢酶（malate dehydrogenase,MDH）活力显著低于放牧+补饲组和放牧组（P<0.05）,MyHCⅡx、MyHCⅡa mRNA表达量和琥珀酸脱氢酶（succinate dehydrogenase,SDH）活力均显著小于放牧组（P<0.05）。综上所述,相比于自然放牧的苏尼特羊,舍饲和放牧+补饲的饲养方式下屠宰性能和胴体品质更优,而放牧和放牧+补饲的饲养方式由于能增强肌肉的氧化代谢能力且氧化型肌纤维比例更高,一定程度上肉品品质更好。     

Comparisons of longissimus muscle metabolic enzymes and muscle fiber types in Korean and western pig breeds

We compared differentially expressed genes and muscle fiber types in the longissimus muscles of Korean native pigs (KNP) and the western meat-producing breeds Landrace and Yorkshire. The KNP breed exhibited a higher muscle fat content and more red meat color as determined by the a^* (redness) value (P < 0.01) and b^* (yellowness) value (P < 0.05) compared to the western breeds. Using differential display RT-PCR, we detected two genes that were differentially expressed in skeletal muscle among the pig breeds. These genes were identified as NADH dehydrogenase subunit 1 and ATPase subunit 6 by cloning and sequencing analysis. Both of these genes are involved oxidative phosphorylation and therefore energy metabolism. The genes were more highly expressed in the KNP breed than in the other breeds, indicating that KNPs exhibit more oxidative metabolism than do the western breeds. We also analyzed the mRNA levels of myosin heavy-chain isoforms such as type I (oxidative), type IIb (glycolytic), and types IIa and IIx (intermediate) fibers using real-time RT-PCR. The mRNA levels of oxidative and intermediate fibers were elevated in the KNP breed, whereas the glycolytic fibers were more highly expressed in the Landrace and Yorkshire pigs. These results suggest that the elevated expression of the oxidation-related metabolism genes NADH dehydrogenase and ATPase is related to meat quality as indicated by a higher content of oxidative fibers and muscle fat, as well as redder meat color.     

A comparison of alternative methods for predicting the carcass composition of crossbred lambs of different breeds and crosses

Carcass data for a total of 2808 lambs from three breed trials were used to evaluate a series of linear measurements, visual scores and the proportions of tissues in joints as predictors of carcass composition. The trials involved crossbred lambs out of different dam types by sires of the main British meat breeds and by Ile de France, Oldenburg and Texel sires. Each trial was carried out over a number of years and involved approximately equal numbers of female and castrated male lambs. Potential predictors were examined in terms of the precision of prediction and in terms of the robustness of prediction equations to differences in sire breed and sex. The overall standard deviation (s.d.) of carcass lean percentage averaged over trials was 4·3. Combinations of simple measurements, including visual fat scores, percentage perinephric and retroperitoneal fat in carcass and M. longissimus dimensions achieved a residual s.d. of 2·5 for carcass lean percentage. The application of an overall prediction equation to individual sire breed means resulted in considerable bias (predicted-actual lean percentage): the mean square deviation was 0·75. In comparison, the sex differences were relatively unimportant. The precision of sample joints was examined in relation to their cost of dissection. The best end neck and shoulder joints offered a high level in relation to cost: typical residual s.d. were 1·5 for carcass lean percentage. Joints and combination of joints with high predictive precision tended to have equations that were robust to differences between sire breeds.