Main characteristics of meat quality and fatty acid composition among different skeletal muscles in Tibetan sheep

To compare the skeletal muscle quality and fatty acid composition of different parts of Tibetan sheep, this experiment selected 3-year-old adult Tibetan sheep ewes bred in Haiyan County, Qinghai Province, and analyzed their triceps, supraspinatus, quadriceps femoris, longissimus dorsi, psoas major, trapezius thoracalis, and gastrocnemius for meat quality and fatty acid composition. The results of meat quality analysis showed that the redness value (a^*, redness) of the upper muscle of Tibetan sheep was the highest 45 min after slaughter, and the lightness value (L^*, lightness) of the longissimus dorsi was closest to the median value. The brightness, redness, and yellowness of the trapezius thoracalis muscles were lower than those of the other muscles at 45 min and 24 h (P < 0.05). The pH of the thoracic trapezius muscle was higher than that of the other muscles, except for the longissimus dorsi and psoas major at 24 h (P < 0.05). The water loss rate of the longissimus dorsi was lower than that of the triceps, supraspinatus, pectoralis trapezius, and gastrocnemius (P < 0.05). The longissimus dorsi had the smallest shear force value, which was lower than that of the triceps, pectoralis trapezius, and gastrocnemius (P < 0.05). Fatty acid determination results showed that a total of 30 fatty acids were detected in seven parts of Tibetan sheep, and saturated fatty acid (SFA) > monounsaturated fatty acid (MUFA) > polyunsaturated fatty acid (PUFA) in all parts, and the SFA content of the longissimus dorsi and thoracic trapezius was higher than that of the psoas major. The content of myristic acid (C14 : 0) in the thoracic trapezius muscle was the highest among the rest of the muscles (P < 0.05). The palmitic acid (C16 : 0) content in the longissimus dorsi muscle was higher than that in the triceps and gastrocnemius (P < 0.05). PUFA content in the gastrocnemius muscle was higher than that in the quadratus pectoralis and supraspinous muscles (P < 0.05). The PUFA/SFA ratio of the gastrocnemius muscle was higher than that of the supraspinatus, longissimus dorsi, and thoracic trapezius muscles (P < 0.05). The n-6/n-3 PUFA ratio of the longissimus dorsi muscle was closer to the optimal ratio (1.0 or 2.0). Comprehensive analysis showed that the quality of the longissimus dorsi of Tibetan sheep is the best, and its fatty acid composition and content in the gastrocnemius are more in line with human health dietary standards, while the content of myristic acid, which is not conducive to human health, is the highest in the thoracic trapezius muscle.