Relationship between myoflber type and fatty acid composition in skeletal muscles of Wagyu (Japanese Black) and Holstein cattle

摘要

The purpose of this study was to evaluate the relationship between myofiber type and intramuscular fatty acid (FA) composition in a concentrate feeding system for Wagyu (n = 6) and Holstein (n = 5) cattle. Animals were intensively fattened with concentrate from 3 months of age until slaughter (26 months of age). After slaughter, 21 skeletal muscles were removed from the animal carcasses, and enzyme and histochemical analysis was carried out. The percentage of intramuscular fat (IMF) content was determined via the Soxhlet method. Intramuscular FA compositions were analyzed by gas chromatography. In the 21 muscles analyzed, the percentage of IMF in 13 muscles was significantly higher in Wagyu than in Holstein cattle (P < 0.05). The percentage of type I myofibers positively correlated with IMF; conversely, percentages of type IIA and IIB myofibers negatively correlated with IMF. Muscles from Wagyu contained a greater proportion of the FAs C16:1, C18:1, and C20:1, and monounsaturated FAs than did those from Holstein (P < 0.001). In Wagyu, the proportion of C18:0 and saturated FA was much lower (P < 0.001). The proportion of FAs with shorter chains (C17) were significantly positively correlated with those in type II (IIA+IIB) myofibers (C18:l, C18:2 n-6, and C20:1; P < 0.05). There were no clear trends in Holstein cattle. The IMF in Wagyu tended to be unsaturated compared with that in Holstein cattle.