Effects of road transportation and preslaughter handling on welfare, physiological stress responses, and meat quality of heifers in tropical climate

Stress has an adverse effect on animal welfare that cannot be ignored, making it imperative to control and minimise stress-inducing elements associated with transportation for ethical, quality, and economic reasons. However, there is little or no evidence in Malaysia regarding the influence of pre-slaughter transportation on stress thresholds and the welfare of heifers subjected to varying distances of road transportation and stocking density. Additionally, there has been a significant increase in demand for red meat, necessitating the movement of animals from their natural habitats to slaughter plants with little or no regard for how these animals are handled and transported before slaughter. Although transportation is stressful for animals, it is unknown if it affects stress thresholds when animals are transported for slaughter. In light of recent incidents, it is becoming increasingly difficult to overlook the risks to animal welfare posed by transportation and handling. No prior study has examined the effects of road transportation and pre-slaughter management on the welfare, physiological stress, and meat quality of heifers in Malaysia. As a result, a study was needed to ascertain the effect of transportation stress on EEG changes and establish a link between these findings and neurohumoral indicators of distress. Thus, this study investigated the effects of road transport and pre-slaughter handling on the welfare, physiological stress, apoptotic index, and meat quality of Brahman crossbred cattle maintained in hot, humid parts of the tropics. The current study examined the relationship between neuroendocrine acute phase proteins (APP), typical characteristics associated with probable stress as measured by electroencephalogram (EEG) activity, meat quality, and apoptotic markers following road transportation of animals. Sixty (60) Brahman crossbred heifers were transported from a cattle feedlot at Universiti Putra Malaysia (UPM) in Serdang to the Shah Alam abattoir complex, Selangor. All animals were transported for (9) nine hours (shortdistance) or seventeen hours (long-distance) and unloaded at the slaughterhouse for slaughter. Both departures and arrivals at the slaughterhouse were formally documented. All animals were transported within the state of Selangor, using a 5-ton lorry fitted with a non-slip floor and rooftop coverings travelled along the highway. Animals were divided into two groups, long (850km) and short (450km) distances, and three stocking densities of 600 kg/m2 (high-SD), 400 kg/m2 (medium-SD), and 200 kg/m2 (low-SD) were used. Blood analysis revealed a significant increase in the intensity of the response to blood parameters cortisol and acute phase proteins (Bovine alpha 1-acid glycoprotein and Serum amyloid–A) (p<.0001). At the farm (baseline values), cortisol and acute phase proteins (Bovine alpha 1-acid glycoprotein and Serum amyloid–A) levels increased significantly (p<.0001) with increasing distance and stocking density and were statistically different from those obtained immediately after unloading and after neck cut. Similarly, the alpha, beta, delta, and theta wave frequencies and Ptot (total power) and MF (median frequency) of the EEG (electroencephalogram) were considerably higher (p<.0001). Long-distance transport also resulted in a significantly higher (p<.0001) response to nociception during slaughter than shorter-distance transport, as demonstrated by APPs (acute phase proteins), cortisol, and EEG. Additionally, results indicated that distances and stocking densities had significant (p<.0001) effects on the apoptotic index, colour, pH, shear force values, WHC (water holding capacity), glycogen levels, and MDA (malondialdehyde assay) content in meat. In conclusion, the current research found that distance and stocking density affected cortisol levels, EEG activity, APPs (Bovine alpha 1-acid glycoprotein and serum amyloid–A), apoptotic index, and meat quality parameters indicated by the significant changes in the parameters listed above. As a result, this data points to possible welfare issues related to animal handling (loading and unloading) and preslaughter following road transportation. Improved animal handling during transportation and decreased average stocking density may contribute to the welfare of animals hauled by road in Malaysia's hot and humid tropics.

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