Influence of Animal Diet and Carcass Electrical Stimulation on the Quality of Meat from Youthful Ram Lambs

Abstract

Sixty ram lambs were group-fed either a high (HC) or low (LC) level of energy intake to an average body weight of 45.8 kg. At slaughter, the lambs were assigned to one of five electrical-stimulation (ES) treatments: (1) nonstimulated (NS) controls, (2) low voltage [45 V; 90-s duration within 3 min of exsanguination (PM)], (3) low:low voltage (45 V; 90-s duration once within 3 min and again within 10 min PM), (4) low:high voltage (45 V; 90-s duration within 3 min PM followed by 145 V; 90-s duration within 45 min PM) and (5) high voltage (145 V; 90-s duration within 3 min PM). All the ES methods resulted in a more rapid pH drop than the NS in the longissimus muscle during the first 3 h postmortem. However, a diet × ES interaction was observed for pH values. Longissimus samples from lambs on the LC diet and receiving ES treatments 3 and 4 never reached an ultimate pH level below 6.0, even though their pH values fell more quickly than those of the control lambs in the first 3 h. Nonetheless, there were no visual signs (e.g., lean color) of dark-cutting meat in these carcasses. Carcasses from the HC diet group had more subcutaneous fat, higher quality grades and higher shear values for loin chops than those from the LC group. Loin chops from carcasses receiving ES treatment 3 had the lowest shear values followed by treatment 5, 2, 4 and 1. Panel tenderness scores were not different among treatments 2 through 5, but controls were less tender than the ES groups. These results suggest that, while ES appears to enhance the tenderness of ram-lamb muscle, certain electrical parameters evoke more beneficial responses than others.