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The activities of calpain and caspase systems during ageing in Longissimus lumborum (LL) and Infraspinatus (IS) muscles of Italian Simmental young bulls ( Bos taurus) were assessed. Samples from 10 animals were collected within 20 min of exsanguination (T0), after 48 h (T1) and 7 days (T2) post mortem. Calpain and caspase activity were evaluated based on the formation of αII spectrin cleavage products of 145 kDa (SBDP145) and 120 kDa (SBDP120), respectively. Caspase activity was also assessed by the presence of poly (adenosine diphosphate-ribose) polymerase-1 (PARP-1) cleavage product. At T0, LL showed higher levels of SBDP145 than IS ( P < 0.01), while SBDP120 and PARP-1 degradation products were similar between muscles. At T1, no difference was found in the level of SBDP145 between muscles, while SBDP120 and PARP-1 cleavage products were not detected. At T2 neither αII spectrin nor PARP-1 cleavage products were found. LL and IS showed different proteolysis after slaughter that was influenced more by calpain than caspase activity, which was detectable only in the early post mortem period. [ABSTRACT FROM AUTHOR]

The early post mortem expression of eight genes potentially involved in meat ageing process and the tenderness of two Italian Simmental young bulls' ( Bos taurus) skeletal muscles differing in their contractile type were evaluated. Samples of Longissimus lumborum ( LL) and Infraspinatus ( IS) muscles were collected from 17 bulls. The messenger RNA ( mRNA) abundances of calpain-1, calpain-2, calpastatin, caspase 3, caspase 9, heat shock p rotein 27 (Hsp27), Hsp40 and Hsp70 were detected by quantitative PCR. The myosin heavy chain-slow and -fast isoform content, the pH48h and the lipid content of the muscles were in line with the contractile and metabolic type. In comparison with the fast LL, the slow IS showed a lower calpain-1/calpastatin mRNA content ratio after slaughtering and a higher Warner- Bratzler Initial Yield value after 7 days of ageing. Hsp27 and Hsp70 mRNA abundances were significantly lower in LL than IS, highlighting their potential role in the ageing process of bovine muscles. [ABSTRACT FROM AUTHOR]