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This study compared the meat quality of Sicilian and Landrace pigs breeds and supported these results with biochemical and histological measurements on the samples collected from the m. Longissimus Dorsi, at the level of the 8th thoracic vertebra, before electrical stimulation. Twenty clinically healthy swine, 10 male (5 for each pig breed) and 10 female (5 for each pig breed), were slaughtered at 1 year of age at a body mass of 135±10 kg and 150±10 respectively for Sicilian and Landrace pigs. Particularly on the muscle considered the morphometric characteristics of FG (fast glycolytic), FOG (fast oxidative glycolytic) and SO (slow oxidative) fibre types and their percentage were determined. Measurements related to myofibrillar fragmentation, sarcomere length and connective tissue properties gave convincing support. Sicilian pig produced more tender meat than Landrace, mainly due to favourable calpain-to-calpastatin ratios.

The aim of the present experiment was to determine the effect of sex and age on histochemical and morphometric characteristics of muscle fibres (myocytes) in lambs born by single, twin, triplet and quadruplet birth. Thirty lambs were slaughtered at 60 days of age; thirty were weaned at 60 days and fed until 120 days with flakes (60%) and food supplements, and then slaughtered. Muscle tissues were obtained from two muscles, namely m. semitendinosus and m. longissimus dorsi of all lambs. For each fibre type, area perimeter and diameter (maximum and minimum) were measured and slow-twitch oxidative fibres, fast-twitch glycolytic fibres, fast-twitch oxidative-glycolytic fibres were histochemically differentiated. The muscles were stained for myosin ATPase, and succinic dehydrogenase. At 60 days, females had fibres larger than males, whereas the opposite was observed at 120 days. Besides, at 60 days, the lambs born by single birth had fibres larger than those born by multiple birth, whereas the opposite was observed at 120 days. Single lambs were heavier than twin lambs and multiple lambs. Fast-twitch glycolytic fibres had the largest size, followed by slow-twitch oxidative and fast-twitch oxidative glycolytic fibres. The dimensions of fibre types in m. longissimus dorsi were larger than in m. semitendinosus (P < 0.001).These muscle fibre characteristics are thought to be important factors influencing meat quality, which is often related to metabolic and contractile properties as determined by the muscle fibre type distribution.

Little is known about the Casertana pig. The aim of this study was to evaluate the effect of sex on histochemical and morphometrical characteristics of muscle fibres (myocytes) in this pure breed and to verify the presence of giant fibres as well as vascularity of the muscle. Finally, maximum shortening velocity and isometric tension were measured in single muscle fibres. Sixteen Casertana pigs (8 males, 8 females) from a farm in Campania (Italy) were slaughtered at one year of age. Muscle tissues were obtained from psoas minor, rhomboideus and longissimus dorsi. Myofibres were stained for myosin adenosine triphosphatase, succinic dehydrogenase, and α-amylase-periodic acid schiff. For all fibre types, the area and perimeter were measured. Slowtwitch oxidative fibres, fast-twitch glycolytic fibres and fast-twitch oxidative-glycolytic fibres were histochemically differentiated; an image-analyzing system was used. The results showed significant differences between the sexes in the size of all three fibre types. The psoas minor muscle had a high percentage of slow-twitch oxidative fibres and contained more capillaries per fibre and per mm2 than rhomboideus and longissimus dorsi, in which fast-twitch glycolytic fibres dominated. The cross-sectional area of all fibre types was larger in longissimus dorsi than in rhomboideus and psoas minor muscles; the giant fibres were present in the longissimus dorsi muscle only. Besides, isometric tension values were higher in fast-twitch glycolytic fibres than in the other ones. Variations in fibre type composition may contribute to meat quality.

The aim of this study was to evaluate the effect of age and sex on histochemical and morphometric characteristics of muscle fibres (myocytes) in lambs born by single or twin birth. Forty lambs were fed mother’s milk and slaughtered at 60 days; 40 weaned at 60 days and fed until 120 days with flakes (60%) and hay (40%) and then slaughtered. Muscle tissues were obtained from two muscles, namely m. psoas major and caput longum m. tricipitis brachii of all lambs. The muscles were stained for myosin ATPase, and succinic dehydrogenase. For each fibre type, area, perimeter, maximum and minimum diameter were measured and slow-twitch oxidative fibres, fast-twitch glycolytic fibres, fast-twitch oxidative-glycolytic fibres were histochemically differentiated. An image-analysing system was used. At 60 days, females had fibres larger than males while the opposite was observed at 120 days. Moreover, at 60 days, the lambs born by single birth had fibres larger than those born by twin birth, while the opposite was observed at 120 days. The fast-twitch glycolytic fibres had the largest size, followed by the slow-twitch oxidative and the fast-twitch oxidative glycolytic fibres. The dimensions of fibre types in caput longum tricipitis brachii muscle were larger than in the psoas major muscle (P < 0.001). This study provides important data on basic characteristics of lamb muscles that, as intrinsic factors, may influence some aspects of meat production and quality.