The Histochemical and Ultrastructural Structures of Avian Latissimus Dorsi Muscle Fiber Types and Changes in Them Caused by Water Copper Level

The histochemical and ultrastructural effects of water Cu on the anterior latissimus dorsi (ALD) muscle of 120 newly hatched broilers were investigated in a 45-day experiment. Two doses of water Cu (250 mg Cu/kg water and 500 mg Cu/kg water) were given to the poults. Two distinct categories (IIIA and IIIB) of slow tonic fibers in the control groups were detected by enzyme reactions. The ultrastructure of the Z-line, mitochondrial content and sarcotubular content differed between the 2 fiber types. In the application of 250 mg Cu/kg water, the histochemical characteristics of the IIIB fibers were clearly different from those observed in the control. In addition, a few IIIB fibers transformed to fast fiber types in their ultrastructure. No transformation of IIIA fiber type occurred, but a significant increase in fiber percentages (86.7%) was observed in the application of 500 mg Cu/kg water. In the application of 500 mg Cu/kg water, there was degeneration in IIIB fibers. Mitochondrial degeneration also occurred in both applications.