초록
Sixty ram lambs, weighting 23.5 kg, were randomly assigned in a $2{\times}3$ factorial arrangement of two dietary energy (high; 11.7 and low; 9.0 MJ ME/kg DM) and three levels of poultry offal meal supplementation (0, 5 and 10%). Lambs were fed ad libitum for 120-day before slaughter. At slaughter, half the lambs in each dietary treatment group were randomly selected for electrical stimulation of their undressed carcasses. The M. Biceps femoris pH and temperatures were monitored at 1, 3, 5, 8 and 24 h postmortem. At 24 h postmortem, the M. biceps femoris was removed from the fight side of each carcass and steaks were obtained for determination of Warner-Bratzler shear force, collagen content and collagen solubility. The results showed that temperature and pH values during the 24-h postmortem were consistently higher (p < .01) and lover (p < .01), respectively, for M. biceps femoris from lambs fed high energy diets than for those fed on low energy diets. Muscles from high energy fed lambs had lower (p < .01) shear force values and higher (p < .01) percent soluble collagen than for low energy fed lambs; total collagen content was not significantly influenced by dietary energy level. Increased the level of poultry offal meal supplementation in the diet to 10% was associated with concomitant increases (p < .01) in muscle tenderness and percent soluble collagen. Electrical stimulation (ES) of carcasses resulted in a lower shear force values for the M. biceps femoris than in non-stimulated carcasses (Non-ES); total collagen content and percent soluble collagen were not significantly affected by ES treatment.