Physiological Reaction of Slaughter Animals during Transport
The easily measured parameters of heart frequency and body temperature were tested as possible indicators of stress intensity in pigs. For the basic research, the heart rate and body temperature values of pigs during individual transport were examined. The highest heart frequency peaks appeared when the pigs were loaded and later when driven into the slaughterhouse. After the first minutes in the transport vehicle, heart rates decreased (130 beats/min) to the relatively constant transport value, Rectal temperatures increased during transport to about 0.7°C above the temperature recorded shortly before loading.
During loading by means of a hydraulic tail-gate lift, measured heart frequencies averaged 200 beats/min; during loading with a ramp, heart rates averaged 218 beats/min. Loading by means of the tail-gate lift is less stressful.
When limits of loading density, temperature and relative humidity are exceeded during transport especial stress is placed on the pig. The testing of various combinations of these factors during constant duration of transport (100 min) showed the strong influence of transport distance. In all situations the heart rate decreased with increasing duration of transport. The degree of decrease was influenced by respective treatment combinations.
Without considering relative humidity and loading density, transport at 19°C produced more favourable values than that at 2°C or 29°C. Relative humidity (60 and 90%) and loading density (0.35 and 0.70 m2/100 kg live-weight) led to differing results in each temperature range. The values were obviously strongly influenced by varying levels of physical activity during thermoregulation and by the amount of room available.
The values at loading and at the end of transport were closely correlated. In many cases there was also a highly significant correlation between rectal, temperature and heart frequency. The measurements taken before the onset of the imposed stress showed no relationship to those values recorded later.
A connection between the tested stress combinations and meat quality showed a tendency which was just recognisable. On the other hand, significant individual differences were found in animals which were not screened for stress susceptibility. In an experiment with animals pre-tested for halothane positive or negative reaction, it was shown under uniform transport conditions that the significant differences between animals were explained almost exclusively by halothane reaction. A further reason for the difference within treatments was due to differing degrees of muscling
KeywordsHeart Rate Rectal Temperature Meat Quality Transport Distance Transport Vehicle
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