Mammalian stress hormones influence the composition and activity of bacteria, which may be important to ruminants such as cattle that rely on these microorganisms for nutrient digestion. Therefore, two experiments were completed to determine if stress hormones such as cortisol, epinephrine, and norepinephrine impact fermentation and digestion characteristics of rumen microbes in an in vitro system. Stress hormones were added to fermentation media in either a continuous or batch culture fermentation system to evaluate changes in the composition of fermentation end-products and/or digestibility. The results of this study imply that exposure to stress hormones can alter gas production, volatile fatty acid profile, and nutrient digestion of rumen microbes. Additional research needs to be completed to quantify how these observations impact specific populations of gastrointestinal microbiota, animal production efficiency, and immunity, particularly in stressed animals such as newly received cattle.

Read the full article in the Journal of Animal Science.