Using infrared thermography on farm of origin to predict meat quality and physiological response in cattle (Bos Taurus) exposed to transport and marketing

Temperature is used as an indicator of animals' response to external stimuli and thus it could potentially be used as an indicator or poor animal welfare and meat quality. Remote monitoring of temperature can be achieved using infrared thermography (IRT) at the farm of origin before animals are sent to slaughter. Relationships between temperatures of cattle measured using IRT on-farm and potential indicators of stress and meat quality were investigated in 481 cattle in 2 experiments, one with sea transport and another with land transport. On-farm measurements included IRT and behavioural assessment of temperament along with measurement of physiological indicators of stress and carcass traits post-mortem. Significant correlations were found between IRT and meat pH, meat colour, creatine kinase, glucose, non-esterified fatty acids, magnesium, and temperament (P < .05). That said, these correlations did not persist across both experiments. Current findings suggest that on-farm IRT could have the potential to assist with the detection of compromised animal welfare and predict meat quality.

Effects of heat stress on animal physiology, metabolism, and meat quality: A review

Heat stress is one of the most stressful events in the life of livestock with harmful consequences for animal health, productivity and product quality. Ruminants, pigs and poultry are susceptible to heat stress due to their rapid metabolic rate and growth, high level of production, and species-specific characteristics such as rumen fermentation, sweating impairment, and skin insulation. Acute heat stress immediately before slaughter stimulates muscle glycogenolysis and can result in pale, soft and exudative (PSE) meat characterized by low water holding capacity (WHC). By contrast, animals subjected to chronic heat stress, have reduced muscle glycogen stores resulting in dark, firm and dry (DFD) meat with high ultimate pH and high WHC. Furthermore, heat stress leads to oxidative stress, lipid and protein oxidation, and reduced shelf life and food safety due to bacterial growth and shedding. This review discusses the scientific evidence regarding the effects of heat stress on livestock physiology and metabolism, and their consequences for meat quality and safety.

Computer vision and remote sensing to assess physiological responses of cattle to pre-slaughter stress, and its impact on beef quality: A review

Pre-slaughter stress is well-known to affect meat quality of beef carcasses and methods have been developed to assess this stress. However, development of more practical and less invasive methods are required in order to assess the response of cattle to pre-slaughter stressors, which will potentially also assist with the prediction of beef quality. This review outlines the importance of pre-slaughter stress as well as existing and emerging technologies for quantification of the pre-slaughter stress. The review includes; i) indicators of meat quality and how they are affected by pre-slaughter stress in cattle, ii) contact techniques that have been commonly used to measure stress indicators in animals, iii) remotely sensed imagery techniques recently used as non-invasive methods to monitor physiological and behavioural parameters and iv) potential implementation of remotely sensed imagery data to perform contactless assessment of physiological measurements, which could be related to the pre-slaughter stress, as well as to the indicators of beef quality. Relevance to industry, conclusions and recommendations for research are included.

Factors influencing the incidence of high rigor temperature in beef carcasses in Australia

Beef carcasses undergoing rapid pH fall while the loin muscle temperature is still high are described as heat-shortened, heat-toughened or ‘high rigor temperature’ carcasses, with subsequent negative effects on quality traits. The aim of the study was to quantify the occurrence of high rigor temperature in beef carcasses across Australia and to identify the causative factors. Data was collected over 4–5 days at each of seven beef processing plants from 1512 beef carcasses. The beef carcasses were from both grass- and grain-fed cattle ranging in days on grain feeding from 0 (grass-fed) to 350 days and the category of cattle ranged from veal to ox and cow. Data collected on the day of slaughter included the duration of electrical inputs at the immobiliser, electrical stimulation and hide puller, longissimus muscle pH and temperature decline, hot carcass weight and P8 fat depth. At grading, ultimate pH, eye muscle area, wetness of the loin surface and colour score were also collected. The temperature at pH 6 was calculated and if it was >35°C, the carcass was defined as ‘high rigor temperature’. Modelling of the data was conducted using GLMM and REML. The occurrence of high rigor temperature across all seven beef processing plants was 74.6% ranging from 56 to 94% between beef processing plants. Increasing days in the feedlot and heavier carcass weights were highly correlated and both caused an increase in the predicted temperature at pH 6 and in the % high rigor temperature (P < 0.05 for both). Longer duration of electrical inputs at the hide puller, fatter grass-fed cattle and fatter male (castrate) carcasses had a higher temperature at pH 6 and higher % high rigor temperature. Modelling showed that if the time to reach pH 6 in the longissimus muscle was 65 v. 105 min, the % high rigor temperature carcasses reduced from 98 to 19% in grain-fed cattle and 93 to 7% in grass-fed cattle. Higher plasma insulin levels at slaughter were associated with a higher temperature at pH 6 (rigor temperature) (P < 0.001). In conclusion, in order to reduce the incidence of high rigor temperature in grain-fed beef carcasses, methods for identifying high rigor temperature carcasses will be required and while some management strategies can be implemented now, others require further research.

Muscle metabolism in sheep and cattle in relation to high rigor temperature – overview and perspective

An increasing number of Australian slaughter plants were found not to meet the Meat Standards Australia (MSA) pH–temperature window, due to high rigor temperatures, particularly at plants where grain-fed animals were slaughtered. Hence, the red meat processing industry in Australia supported a research program focused on resolving this issue, as carcasses that do not meet the MSA pH–temperature window are excluded from MSA grading. This special issue of Animal Production Science describes the outcomes of a major program identifying ante- and post-mortem factors related to heat-induced toughening in both beef and sheep meat through literature reviews and targeted research to find interventions to prevent the impact of high rigor temperature on meat quality, particularly tenderness. This paper provides an overview of the outcomes of the research program, some of which require further research before implementation. It is suggested that an entire supply-chain approach be applied to establish the most efficient and cost-effective way of reducing the incidence of high rigor temperature.

Potential nutritional strategies for the amelioration or prevention of high rigor temperature in cattle – a review

Environmental conditions influence animal production from an animal performance perspective and at the carcass level post-slaughter. High rigor temperature occurs when the animal is hyperthermic pre-slaughter, and this leads to tougher meat. Hyperthermia can result from increased environmental temperature, exercise, stress or a combination of these factors. Consumer satisfaction with beef meat is influenced by the visual and sensory traits of the product when raw and cooked, with beef consumers commonly selecting tenderness of the product as the most important quality trait. High rigor temperature leads to a reduction in carcass and eating quality. This review examines some possible metabolic causes of hyperthermia, with focus on the importance of adipose tissue metabolism and the roles of insulin and leptin. Potential strategies for the amelioration or prevention of high rigor temperature are offered, including the use of dietary supplements such as betaine and chromium, anti-diabetic agents such as thiazolidinediones, vitamin D, and magnesium (Mg) to provide stress relief.