Abstract: AbstractThe difference of the muscle fiber diameter,density and the shear force of breast muscle among the three Aba Tibetan chicken strains, as well as the relationship between each index and muscle tenderness were analyzed the histological differences in muscle fiber development of Aba Tibetan chicken. The three Aba Tibetan chicken strains were selected as the research objects in the experiment, the number and density of muscle fibers in the breast and leg muscle of the chickens were measured using tissue sectioning technology, and the breast muscle were tested for shearing force, whose results showed that the average breast muscle fiber diameters of the three strains were longer than the leg muscle, but the density of muscle fibers was lower than the latter. And the difference in the diameter and density of the leg muscle muscle fibers in the three strains were not significant, and none of them reached a significant level. The shearing force of breast muscle of the lightest A-Zang 1 line was only 79.36 N, which is significantly lower than that of the A-Zang 2 and 3 line, which shows that the breast tenderness of the A-Zang 1 line was the best among the three lines.

Key words: Aba Tibetan chicken, muscle fibers, muscle tenderness, breeding