The stress response and its effects on dairy cattle

Authors: Carroll, Jeffery - Jeff Carroll; Sanchez, Nicole; Broadway, Paul; COLLIER, ROBERT - University Of Arizona

Submitted to: Proceedings of the Penn State Dairy Cattle Nutrition Workshop Pre-Conference Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2019
Publication Date: 11/5/2019
Citation: Carroll, J.A., Sanchez, N.C., Broadway, P.R., Collier, R. 2019. The stress response and its effects on dairy cattle. Proceedings of the Penn State Dairy Cattle Nutrition Workshop Pre-Conference Symposium. p. 11-15. Hershey, PA., November 5-6, 2019.

Interpretive Summary: As consumer preferences for more naturally-produced animal protein sources increases, policies are being adopted that reduce and/or eliminate the use of antibiotics in livestock production. In an effort to meet these consumer demands, livestock producers are seeking natural supplements as antibiotic alternatives that can be used to improve animal health while maintaining an acceptable level of productivity. One particular class of natural supplements being studied rather extensively is yeast. Both live yeast and yeast cell wall products are thought to have beneficial effects on animal health as well as animal performance. To evaluate the effectiveness of a commercially available yeast product, scientists within the Livestock Issues Research Unit teamed up with an industry partner to determine if providing this yeast product would reduce the severity of the stress response in cattle. Results from this study indicated that providing the yeast product in the diet not only reduced the severity of the stress challenge, but also altered the metabolic response in a manner thought to be beneficial to the cattle. These data will be of interest to livestock producers, veterinarians, and scientists working in the field of cattle health and nutrition.

Technical Abstract: While the debate among animal scientists concerning the definition and quantification of “stress” as it relates to animal productivity and well-being is ongoing, there is little doubt that an increased appreciation and understanding of the effects of “stress” on livestock production has emerged throughout the scientific community and with livestock producers. Cattle experience numerous environmental, managerial, and nutritional stressors throughout the production cycle that could potentially inhibit overall productivity and well-being due to neuroendocrine disruption and stress-induced immunosuppression. Generally, in the case of livestock, stressors can be grouped into the following three broad categories: 1) psychological stress; 2) physiological stress; and 3) physical stress. While some stressors can be prevented or overcome through alternative management practices and various nutritional strategies, some stressors such as thermal stress (heat and cold stress) are often difficult to prevent and impose significant economic burdens on the cattle industry. In a search for non-antibiotic nutritional strategies to help reduce stress, producers turned to more natural supplements. For example, supplementing cattle diets with microbiological fractions (e.g., yeast cell wall fractions) and/or probiotics (e.g., live yeast) in the diet has potential to reduce stress and provide support the immune system. While mechanistic pathways associated with how yeast cell wall fractions or live yeast products mediate the stress and immune responses have not been fully elucidated, it is postulated that there are multiple modes of action including direct binding to pathogens, direct stimulation of immune cells, and alterations in glucose uptake and utilization.