Inhibition of nitric oxide release pre-slaughter increases post-mortem glycolysis and improves tenderness in ovine muscles

The aim of this experiment was to determine the effect of inhibiting the release of nitric oxide (NO) pre-slaughter in lambs on post-slaughter muscle metabolism and meat quality. Exercise was used as a positive control as NO is known to be released in skeletal muscle during exercise. Forty Border Leicester × Merino lambs were assigned to the treatments L-NAME (NO synthase inhibitor) infusion (0 mg/kg vs. 30 mg/kg, 135 min pre-slaughter) and exercise (none vs. 15 min immediately pre-slaughter). The inhibition of NO release using L-NAME reduced Warner–Bratzler shear force (WBSF) in the longissimus thoracis et lumborum (LTL) after 3 days of ageing, while the Semimembranosous (SM) was unaffected. Inhibition of NO release with L-NAME resulted in altered glucose metabolism as indicated by reduced plasma glucose pre-slaughter particularly in exercised lambs, reduced LTL and SM glycogen of non-exercised lambs post-slaughter and increased SM lactate in exercised lambs post-slaughter. In conclusion, inhibition of NO Synthase with L-NAME pre-slaughter increases post-mortem glycolysis and improves tenderness in the loin muscle.