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Researchers lay groundwork for evaluating cattle stress

A two-year research project has resulted in considerable progress towards developing an objective method of assessing the stressfulness of management practices used in beef production.

"Having the ability to objectively measure stress in cattle would allow producers to cut production costs and losses associated with stress by altering management practices to minimize its occurrence," says Dr. Gerry Mears, an Agriculture and Agri-Food Canada Lethbridge Research Centre scientist who led the study, which was funded by the Canada Alberta Beef Industry Development Fund (CABIDF).

"Furthermore, having an acceptable means of assessing stress would allow cattle producers to be proactive in identifying and rectifying practices detrimental to animal welfare, cutting short some common animal welfare claims."

Cattle stress can result in apprehension, reduced production and reproduction, compromised health or even death. Unfortunately, historically, there has been no way to objectively assess cattle stress during regular production practices.

"In the study, we performed a series of experiments to evaluate the usefulness of several physiological and behavioural responses to stress as indicators of the relative stressfulness of various management practices," says Mears. "The management practices we investigated included dehorning, castration, mixing with unfamiliar animals, transportation, and a combination of hot-iron branding and castration."

Building on results from previous studies conducted with sheep, researchers measured plasma cortisol, plasma beta endorphin, body temperature, heart rate and behaviour among cattle before, during and after routine management practices.

All of the procedures examined produced responses to varying degrees, says Mears. Dehorning and castration procedures resulted in significant physiological and behavioural changes. Mixing steers with an unfamiliar group of animals resulted in increased heart rate measurements that indicated the presence of stress. In these mixing situations, there were also an increased number of aggressive encounters compared to when the steers remained in their respective home groups.

Three hours of transportation also produced a stress response in cattle, says Mears. "However, the physiological responses were short-term and most steers showed a return to pre-transport blood cortisol and heart rate levels within one hour."

Following the dual procedure of branding and castration, the calves' plasma cortisol values, which can indicate stress, were more sustained than those of the single procedure animals. Furthermore, the calves in the dual procedure exhibited more severe physical reactions (90 percent fell down) than those exposed to a single procedure.

The results of this study, says Mears, have documented and clarified the physiological and behavioural responses of calves to several management practices. But, researchers are not yet ready to make definite assessments of the stressfulness of the various management practices or prepare guidelines for producers.

More research is needed in order to fully objectively assess stress in cattle, particularly with the use of non-invasive measures currently being developed, he adds. Once that happens, the industry will be better equipped to develop of a set of science-based best management practices that would anticipate the evolution of regulations and protocols set out by governments and the food industry.

CABIDF is a joint $16.4 million fund of Alberta Agriculture, Food and Rural Development and Agriculture and Agri-Food Canada. The Fund is administered by Alberta Beef Producers and has supported more than 50 projects in six major categories identified to benefit the Alberta beef industry.

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