Comparative Analysis of Myofiber Characteristics, Shear Force, and Amino Acid Contents in Slow- and Fast-Growing Broilers

Abstract

Skeletal muscle fiber characteristics are pivotal in assessing meat quality. However, there is currently a lack of research precisely quantifying the total number of myofibers (TNM) of skeletal muscles. This study used Arbor Acres (AA) broilers and Wenchang (WC) chickens to determine the TNM of several skeletal muscles and the meat quality of the pectoralis major muscle (PM). The results showed that the TNMs of the PM in AA males and females were 935,363.64 ± 92,529.28 and 873,983.72 ± 84,511.28, respectively, significantly higher than those in WC (511,468.97 ± 73,460.81 and 475,371.93 ± 70,187.83) at 7 days of age (p < 0.01). In terms of gastrocnemius medialis in AA males and females, we recorded values of 207,551.43 ± 31,639.97 and 177,203.23 ± 28,764.01, showing a significant difference compared to the values observed in WC (146,313.03 ± 29,633.21 and 124,238.9 ± 20,136.95) (p < 0.01). Similarly, the levels of gastrocnemius lateralis exhibited a significant difference between AA and WC (p < 0.01). Furthermore, the essential, umami, and sweet amino acids were found to be significantly higher in WC compared to AA (p < 0.01). These findings offer valuable data and insights for accurately quantifying the TNM in livestock and for the development of further genetic breeding strategies for meat quality.

Keywords: Arbor Acres broiler; Wenchang chicken; meat quality; total number of myofibers.

Figure 1

Skeletal muscle fibers of Arbor Acres (AA) broilers and Wenchang (WC) chickens at D7: (A) The prepared H&E-stained muscle sections were scanned to create whole slide images (WSIs). The left side displays an example of the WSIs for the pectoral muscle, and the right panel illustrates the region of interest, which corresponds to the pectoralis major muscle (PM) for subsequent sectioning and counting. (B) The left panel illustrates an example of WSI characteristics of the drumstick. The central and right panels represent the region of interest, corresponding to the gastrocnemius medialis (GM) and gastrocnemius lateralis (GL), respectively, with these areas clearly marked for further processing. (C) The first and second rows represent the image tiles of skeletal muscle sections from AA broilers and WC chickens, respectively, using males as representative examples. The images progress from left to right, depicting representative image tiles of the PM, the PM post-processed with MyoV software (v. 1.0), the GM, the GM enhanced through MyoV, the GL, and the GL after MyoV progressing. All images are presented at a resolution of 1024 × 1024 pixels, with a scale bar of 20 µm.

Figure 2

Muscle fiber characteristics of the two chicken breeds at D7: (A) The total number of myofibers (TNM) of the pectoralis major muscle (PM), gastrocnemius medialis (GM), and gastrocnemius lateralis (GL) of Arbor Acres (AA) broiler and Wenchang (WC) chicken males. (B) The TNM of PM, GM, and GL of AA and WC females. (C) The myofiber cross-sectional area (CSA) of different skeletal muscles of AA and WC males. (D) The CSA of PM, GM, and GL of AA and WC females. * indicates p < 0.05 and ** indicates p < 0.01.