Electron microscopic changes in muscle and liver of feed restricted growing lambs

Fifteen Najdi male lambs, 30.1±0.3 kg live weight and 3.5 months of age, were used to evaluate the effect of feed restriction on the muscle fiber diameter, sarcomere length, tissues architecture, glycogen content and ultra-structure changes in the muscle of Longissimus dorsi and liver. Lambs were randomly allocated to one of three groups (5 lambs each) throughout 35 days experimental trial. Feeding treatments were ad libitum (Control, C), 75% (25% feed restriction, 25R) and 60% (40% feed restriction, 40R) of the ad libitum C intake, respectively. Significant smaller fiber diameter was associated with restricted feeding groups. Control group liver samples contained more glycogen than either 25R or 40R groups. The main ultra-structural changes were associated with swollen mitochondria; reduce glycogen granules and lipid concentration in the liver samples especially in 40R group. Myofibril diameter of the muscle L. dorsi of C group was significantly larger (13.5 μm) than 25R (12.5 μm) and 40R (11.5 μm) groups. Also, C group had significant longer sarcomere (2.03 μm) compared to the 25R (1.87 μm) and 40R (1.93 μm) groups.