Managing pre-slaughter stress to optimise glycogen

Summary

This study consisted of two experiments. Experiment 1 investigated the potential for muscle glycogen loss due to stress and feed withdrawal during the transport and lairage periods undertaken with commercial slaughter. Experiment 2 tested the impact on muscle glycogen of feeding two levels of metabolisable energy and shearing prior to consignment for slaughter.

In both experiments glycogen and ultimate pH (pHu) were measured in the topside and eye round muscles. Topside was chosen rather than backstrap due to practical difficulties encountered with sampling the backstrap in a commercial environment. The topside is more accessible than backstrap in both the live animal and carcass. Previous research has shown a strong correlation (figure 0.01) between backstrap and topside as these two muscles have a similar range of fibre types. By extrapolation affects seen in topside glycogen levels can be expected in backstrap glycogen levels as well. Eye round was measured as it has a different range of fibre types to both backstrap and topside that make it more susceptible to the affects of stress. It was included specifically to be an indicator of stress.