Electrical Stimulation to Improve Carcass Quality of Finishing Brahman x Native Beef Cattle

Abstract

The experiment was conducted to study the effect of electrical stimulation (ES) on the ultrastructural changes and to improve the tenderness trait of beef muscle. Nine crossbred steers (Brahman x Native) were used in this study. The animals were slaughtered and splitted longitudinally into two sides. Only the left side was electrically stimulated (ES) within 1 hr postmortem prior to chilling. Each carcass was stimulated with 1 ampere 500 volts (AC) for 2 minutes employing 30 impulses (2 sec duration with 2 sec interval between impulses). After stimulation the ultrastructure of Longissimus dorsi (LD) muscle was observed by using Transmission Electron Microscope. The eating quality of the LD, Infraspinatus (IS) and Biceps femoris (BF) muscle were determined by using the Warner-Bratzler shear device (W – B shear) and sensory evaluation. Improvement of the lean color, marbling score, shear force value and sensory scores of beef were pronounced in ES muscle samples after 24 hr chilling. There were significant differences in lean color and marbling score between ES and unstimulated (non – ES) LD muscle sample. The LD lean color score of ES muscle (2.33) was brighter than non-ES muscle (3.00). The W – B shear value of the stimulated IS muscle was significantly (P<0.01) lower than non – ES muscle (2.09 VS 2.59 kg). A similar result was obtained for the LD muscle, 3.66 VS 5.38 kg for ES and non – ES, respectively. Carcasses which were electrically stimulated has lower W – B shear values in BF muscle, 4.76 and 5.97 kg for ES and non – ES, respectively, but not statistically significant. ES improved juiciness in the BF but did not improve flavor and the overall acceptability of all muscle samples. The ultrastructural postmortem changes in the LD muscle sample were observed. Under the Transmission Electron Microscope, ES caused specific structural changes where the LD muscle sample showed irregular bands, swollen and superstretching of the myofibril and myofiament, absent H zone and Z line. These structural changes did not occur in the non – ES muscle sample.