The influence of fiber size distribution of type IIB on carcass traits and meat quality in pigs

The effects of detailed characteristics such as the size and proportion of type IIB fibers in longissimus thoracis muscle on carcass traits and pork quality were investigated. A total of 96 pigs were classified into four groups by the proportion of different IIB fiber sizes. Group NS (high proportion of both small- and normal-sized IIB fibers) had a higher total number (136.4) and density (23131) of type BB fibers, backfat thickness (3720 mm) and intramuscular fat content (4.77%) than the other groups (P<0.05), whereas Group NS had the lowest values of cross-sectional area (3413.85 mu m(2)) and diameter (60.15 mu m) of type BB fiber among the groups (P<0.05). Pig muscles with higher percentage of large BB fibers exhibit tougher, lighter and more exudative meat than pig muscles with a higher proportion of small- or normal-sized IIB fibers. Therefore, an increase in the proportion of large BB fibers causes poor quality of pork. (C) 2013 Elsevier Ltd. All rights reserved.