Effect of lairage timing and duration on rumen physiology and muscle glycogen

Summary

​The depletion of muscle glycogen reserves due to reduced dietary glucose precursors and/or physiological stress are the primary factors associated with dark cutting. It has been commonly accepted that feedlot cattle consuming high energy diets and gaining a minimum of 0.8 kg/d receive adequate nutrition to ensure muscle glycogen concentration is maximised prior to dispatch from the feedlot. However, dark cutting remains a significant issue in feedlot cattle in Australia and thus further research is required to minimise the incidence of dark cutting. 

Although we believe muscle glycogen concentration is maximised prior todeparture from the feedlot, the period of time from feedlot dispatch to slaughter may impact muscle glycogen concentration at slaughter which is an important factor associated with meat colour and ultimate pH. This project evaluates the effects of lairage duration and timing on rumen temperature and pH and muscle glycogen levels at slaughter. We hypothesize that cattle exposed to longer periods of transport and lairage will have higher ruminal pH, higher ruminal temperature, higher ultimate pH, reduced muscle glycogen levels, and darker meat colour. 

This project will determine if the duration and timing of lairage havean effect on rumen physiology, muscle glycogen levels, and carcase characteristics. A 2 x 2 factorial will examine two dispatch times from the feedlot (afternoon before; morning of slaughter) and two slaughter times (morning slaughter; afternoon slaughter). This experiment will guide future recommendations for best practice dispatch & lairage of grain-fed cattle.