Electrical stimulation effects on tenderness of five muscles from Hampshire x Rambouillet crossbred lambs with the callipyge phenotype

The objective of this study was to determine effects of electrical stimulat ion (ES) on muscle quality and sensory traits of 12 Hampshire x Rambouillet callipyge lambs. One side of each carcass was randomly assigned to an ES t reatment of 550 V and 60 Hz of electricity for 2 s on and 2 s off 15 times. The other side was a nonstimulated control (NES). Heated calpastatin, sarc omere length, myofibrillar fragmentation index (MFI), Warner-Bratzler shear (WBS), and trained sensory panel values were measured on the semitendinosu s (ST), semimembranosus (SM:), longissimus (ML), supraspinatus (SP), and tr iceps brachii (TB) muscles. Electrically stimulating the carcass sides indu ced-a more rapid (P = .001) pH decline in the longissimus muscle, and ES si des had a brighter (P = .001) red color of loineye than nonstimulated sides . At d 14 of storage (2 degrees C), the TB had the highest (P < .05) MFI va lue, indicating more protein degradation, and the ST and ML muscles had the lowest MFI (P = .008). Regardless of ES treatment, SM and ML had the highe st (P < .05) WBS values. The ST muscle had higher (P < .05) WBS values than the SP but did not differ (P > .05) from the TB muscle. Electrical stimula tion had no effect on WBS or any trained sensory panel values (P > .05). Th e percentage of loin chops rated slightly tender or better was improved 30 to 34% by electrical stimulation (P < .05). The ML muscle was scored lower (P < .05) in sustained juiciness compared with the SM, SP, and TB but did n ot differ (P > .05) from the ST muscle. The SM and ML muscles were rated lo wer (P < .05) in initial and sustained tenderness scores than other muscles . Tenderness scores were higher (P < .05) for the TB than for the SP but di d not differ (P > .05) from the ST muscle. Electrically stimulating callipy ge carcasses improves the tenderness of loin chops by increasing the percen tage of chops rated from slightly tough to slightly tender.