Influence of carcass weight on meat quality of commercial feedlot steers with similar feedlot, slaughter and post-mortem management.

The effects of beef carcass weight on muscle pH/temperature profile and selected meat quality attributes were evaluated. Twenty-six carcasses from light (≤260kg, n=15) and heavy (≥290kg, n=11) feedlot steers were randomly allocated and stimulated with low voltage electrical stimulation (LVES) for 30s at 7min post-mortem (pm). Quality evaluations were carried out on samples from the Longissimus et lumborum (LL) muscle from the left side of each carcass. Heavier carcasses showed faster pH decline and slower (P<0.05) temperature decline at 45min, 3, 6, 12 and 24h pm. Heavier carcasses passed through the heat shortening window (i.e. at pH6, temperature was >35°C) but there was no sign of sarcomere shortening in any carcass. Significantly lower (P<0.05) shear force values were recorded in the heavier carcasses at 3days pm but at 14days pm, heavier carcasses had numerically lower but not significantly different shear force. Heavier carcasses produced numerically higher but not significant (P>0.05) drip loss at 3 and 14days pm as well as higher L* (meat lightness) (P<0.05) and C* (chroma) (P<0.05) values early (2days) pm. However, at 14days pm, there were no significant differences between the light and heavy carcasses in terms of L* and C*. No significant difference was observed between heavy and light carcasses in terms of H* at 2 and 14days pm. The study showed that heavier carcasses which favor slaughter house pricing can be produced and processed alongside lighter carcasses without significant detrimental effects on meat quality by using low voltage electrical stimulation (LVES).