The effect of fasting on liveweight and carcass characteristics in lambs

In two experiments, involving 250 and 300 lambs, respectively, lambs were fasted (with access to water) and slaughtered after 0, 1, 2, 3 and 4 days. The effects of initial fat score, initial liveweight and sex (wethers and ewes) on the patterns of loss in liveweight, hot carcass weight and carcass characters (fat depth at the GR and C sites, kidney fat weight and the weights of chemical carcass components) were examined. In experiment 2 the effects of weaning and transport on fasting losses were also examined. The rate of liveweight loss (expressed as a percentage of initial liveweight) was greater in the initial stages of the fast and was affected by fat score, with a greater loss in lambs with a lower fat score. The pattern of loss in hot carcass weight with fasting was curvilinear and in experiment 2 was affected by both fat score and liveweight, with leaner, heavier lambs having a greater loss. In experiment 2 the decrease in fat depth at the GR site interacted with fat score, with a greater loss in lambs with a lower fat score. Transport per se had no effect on hot carcass weight or carcass characteristics.