Abstract
The aim of this study was to investigate the histochemical parameters of muscle fibers, and to estimate the correlation between these histological parameters and carcass traits in pigs. A total of 230 crossbred Duroc×(Yorkshire×Landrace) pigs (149 gilts and 81 castrated male pigs) was evaluated. Carcass traits (carcass weight, backfat thickness, and loin eye area), muscle fiber size (cross- sectional area, diameter, and perimeter), muscle fiber number (density of fibers/mm 2 and total number of fibers), and fiber type composition (percentages of myofibers and relative areas of each fiber type) were evaluated. Mean cross-sectional area (CSA) and type IIB fiber CSA were positively correlated to carcass weight, backfat thickness and loin eye area. Mean fiber CSA was mostly related to type IIB CSA (r=0.98) as a result of the high percentage of type IIB fibers in the longissimus muscle. Correlations between fiber diameters and perimeters were also high, and showed similar results with CSA. Mean fiber density was negatively correlated to carcass weight (r=-0.24), backfat thickness (r=-0.18) and loin eye area (r=-0.27). To the contrary, total fiber number was positively correlated with carcass weight (r=0.27) and loin eye area (r=0.53). Carcass weight and loin eyZe area were not significantly related to muscle fiber composition. For backfat thickness, there was an opposition between type IIA percentage, which was positively related and type IIB percentage, which was negatively related. Fiber type composition of type I and IIA fibers were negatively correlated to that of type IIB fibers (r=-0.67 to -0.74). In the present study, carcass weight and loin eye area were positively correlated to CSA and negatively correlated to fiber density. But, these relationships were generally low. The fiber density was strongly affected by muscle fiber size and the total fiber number was affected either by CSA of muscle fiber and loin eye area. Fiber type composition was much more related to their numerical abundance than their CSA. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 3 : 428-433)
Highlights
One of the unique characteristics of skeletal muscle is its diversity in morphological and biochemical characters.In nature, muscles always comprise a mixture containing all of the fiber types (Chang et al, 2003)
The predominant characteristic of a given muscle is determined by its relative composition in the different muscle fiber types
The aim of this study was to investigate the histochemical parameters of muscle fibers, and to estimate the correlation between these histological parameters and carcass traits in pigs
Summary
One of the unique characteristics of skeletal muscle is its diversity in morphological and biochemical characters.In nature, muscles always comprise a mixture containing all of the fiber types (Chang et al, 2003). IIB fiber CSA were positively correlated to carcass weight, backfat thickness and loin eye area. Carcass weight and loin eye area were positively correlated to CSA and negatively correlated to fiber density.
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