Cattle handling at abattoirs. II. The effects of rest in transit and duration of the resting period before slaughter on carcass weight, bruising and muscle properties

Abstract

In two experiments, we examined the effects on carcass weight, bruising and muscle properties of resting cattle during a long rail journey and for various periods at an abattoir before slaughter. In experiment 1, 170 Shorthorn bullocks (mean liveweight 556 kg) were transported 90 km by road and 650 km by rail, with three groups (34 per group) going directly to an abattoir and two groups resting once for one day midway during the rail journey. The resting periods at this abattoir were 2, 3, 4,2 and 3 days, respectively. In experiment 2, 240 cows (mean liveweight 424 kg) were transported 190 km by road and 965 km by rail, with three groups (40 per group) going directly to another abattoir, two groups resting once for one day and one group twice for one day during the rail journey. The resting periods at this second abattoir were 1.5, 2.5, 3.5, 1, 2 and 1 day(s), respectively. All cattle had access to feed and water during resting periods and to water until slaughter. As the total resting period after the start of the rail journey and before slaughter increased, the percentage of carcasses with high pH values for M. longissimus dorsi decreased (P < 0.05); correlations for pH 24 h post mortem and ultimate pH were -0.97 and -0.71, respectively. The correlation between total resting period and shear values (initial yield and peak force) were c. -0.5. A resting period during the rail journey was as effective as that time spent resting at the abattoir. Cattle transported directly by rail to the abattoir had a greater bruise score than those rested en route, although cows rested twice were as bruised as those going direct. Treatment had no significant effect on carcass weight or systematic effect on cooking loss. Very high incidences of high ultimate pH values in one group of bullocks (29.4%) and another of cows (20.5%) occurred following periods of stress when slaughtering was interrupted by unavoidable stoppages.