425 Effects of pre-mortem stress on protein expression, steak color, and myofibrillar fragmentation index in the longissimus lumborum following harvest. (30th November 2020)

• Record Type: Journal Article
• Authors: Briggs, Reganne K; Legako, Jerrad F; Broadway, Paul R; Carroll, Jeff A; Burdick-Sanchez, Nicole C; Smith, Zachary K; Thornton, Kara J; Ramanathan, Ranjith
• Is Part Of: Journal of animal science. Volume 98(2020)Supplement 4
• Page Start: 198
• Page End: 199
• Publication Date: 2020-11-30
• Subjects: Beef -- Heat Shock Proteins -- Oxidative Stress; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skaa278.366
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: Undesirable variation in beef tenderness and stability of flavor and color may be associated with the abundance of heat shock proteins (HSP). This study aimed to determine whether pre-mortem stress impacts HSP expression in the skeletal muscle following harvest. Forty Holstein steers were administered an i.v. bolus dose of adrenocorticotropic hormone (ACTH; 0.1 IU/Kg BW) to mimic an acute pre-mortem stress. Longissimus lumborum (LD) biopsy samples were taken prior to the ACTH challenge. Serum cortisol was measured every 0.5 h from -2 to 6 h relative to the ACTH challenge. Skeletal muscle and blood samples from 10 steers were collected at each harvest timepoint at (2, 12, 24 and 48 h post-challenge). Samples were collected from the LD immediately after harvest and after 14 d of aging. Protein expression of HSPβ1, P-HSPβ1, HSPβ5, and DJ-1 was analyzed in muscle samples taken prior to the ACTH challenge, at harvest, and after 14 d of post-mortem wet aging. In addition, steak color and myofibrillar fragmentation index (MFI) was analyzed in 14 d aged samples. Harvest time point following the ACTH challenge affected (P < 0.05) protein expression of HSPβ1 and P-HSPβ1. Protein expression of DJ-1 prior to the ACTH challenge was different (P < 0.05) among steers harvested at different timepoints. In addition, time of harvest had no effect on HSPβ5 expression (P > 0.05). Regarding steak color, time of harvest had an effect (P < 0.01) on a*, b*, hue, chroma, and ratio, but no effect (P > 0.05) on L*. Lastly, time of harvest had an effect (P < 0.05) on MFI. These data indicate that HSP expression, steak color, and MFI in the LD after harvest may be related to time of harvest following a stressful event pre-mortem.