Study on muscle fiber characteristics of different muscle parts of different cattle breeds

Objective To analyze the differences in muscle fiber characteristics among different cattle breeds and muscle parts, and explore the correlation mechanism between muscle fiber indicators and beef quality traits.

Methods Fourteen healthy bulls aged 24 - 26 months from Kazakh cattle (HSK), Xinjiang Brown cattle (XJH) and beef-type Xinjiang Brown cattle (RYHN) were selected, fattened uniformly for 200 days under identical feeding conditions and slaughtered collectively afterwards. Muscle samples were harvested from six locations including infraspinatus, rhomboideus, longissimus dorsi, psoas major, semitendinosus and biceps femoris. Paraffin sections were prepared and stained with hematoxylin-eosin (HE) for histological observation. The number, cross-sectional area and diameter of muscle fibers as well as Warner–Bratzler shear force of muscle were determined, followed by correlation analysis.

Results Across all sampled muscle parts, Xinjiang Brown cattle and beef-type Xinjiang Brown cattle had extremely significantly fewer muscle fibers (P<0.01), but remarkably larger fiber cross-sectional area and fiber diameter (P<0.01) compared with Kazakh cattle; no significant differences in all measured indicators existed between conventional and beef-type Xinjiang Brown cattle (P>0.05). For muscle parts, rhomboideus owned the maximum fiber cross-sectional area and diameter, while semitendinosus had the highest fiber count. The shear force values of biceps femoris, infraspinatus, rhomboideus and longissimus dorsi in beef-type Xinjiang Brown cattle were lower than those of the other two breeds.

Conclusion Both cattle breed and anatomical site significantly affect the histological properties of muscle fibers. Fiber diameter and cross-sectional area are significantly positively correlated with muscle shear force, whereas fiber number is significantly negatively correlated with shear force. The findings provide theoretical reference and basic data for selective breeding improvement and targeted meat quality optimization of beef cattle in Xinjiang.