Abstract:
Pre-slaughter loss of live mass due to transportation is a well-known occurrence in the beef production industry – predominantly regarding the economic sustainability thereof because it represents a potentially significant loss in monetary value. It is widely accepted that stress is a major contributor to the physiological tissue loss occurring during transport. However, the multi-factorial nature of pre-slaughter stress and the inevitability of some of these stressors, such as heat stress, fasting, handling and transport, has made it difficult in the past to predict the expected losses during a journey to the abattoir for slaughter. Individual variation among the cattle transported and slaughtered as a group has been presumed the main explanation for the variation seen in live mass losses, and the reason for reduced carcass mass. The purpose of this study was to determine if variation in certain fixed factors among transported feedlot cattle, including breed type, pre-slaughter mass, carcass classification, fat %, subcutaneous fatness (SCF), β-adrenergic agonist treatment, ADG, FCR, dressing % and CCM, significantly contribute to the variation in the percentage of transportation loss (%TL) of typical feedlot cattle transported for short (less than 100km) distances to the abattoir, as well as to determine the expected range of live mass loss due to transport based on these factors. Empty body mass prior to slaughter and post-transport masses were used to determine individual transport losses. Data on all the above factors were also recorded and used for the analysis. The results indicate that average losses between 1.51% and 2.01% can be expected for typical feedlot cattle in South Africa being transported for short distances (less than 100km) to the abattoir. The greatest contributing factor to the variation observed in transport losses was fat % (P = 0.007), which had a negative relationship with %TL. Higher fat % therefore correlated with lower transport losses. This also explains the significance of β-agonist treatment (P = 0.042), and the trends observed in breed type and carcass classification (for datasets 1 and 2), despite their insignificance (P = 0,957; P = 0.,160; P = 0,698). Live mass, cold carcass mass (CCM) and dressing % showed no trend and were all found to have insignificant effects on %TL (P = 0,519), (P = 0,300; P = 0.820), (P = 0,450; P = 0,230). Average daily gain, FCR and SCF also all had P >0.05 significance values, and therefore had no effect on %TL. The results of this study show that fatter animals have a tend to lose less physiological tissue as moisture, but also that the difference between losses of lean and fat animals are relatively small, consistently staying below 2.5%, regardless of fat %, β-adrenergic agonist treatment, breed or carcass classification. More research is needed to determine if longer transport distances have an effect on this value, and what the extent of that effect would be.
