Heat Stress: What's the Gut Got To Do With It?

This information was presented the 2015 Herd Health and Nutrition Conference, organized by the PRO-DAIRY Program in the College of Agriculture and Life Sciences at Cornell University. Softcover copies of the entire conference proceedings may be purchased at http:// ansci.cornell.edu/dm/ or by calling (607) 255-4478.Heat stress (HS) is a global problem which jeopardizes animal welfare, profitability, and global food security. Indirect effects of HS such as reduced feed intake contribute to, but do not fully explain, decreased productivity. Heat stressed animals initiate metabolic changes that do not reflect their plane of nutrition. This indicates that HS directly effects metabolism and productivity independent of reduced feed intake. In a variety of species, environmental hyperthermia compromises the intestinal barrier function resulting in increased permeability to luminal content including bacteria and bacterial components. Presumably, heat stress causes leaky gut in ruminants as well. The leakage of luminal content into the portal and ultimately the systemic circulation elicits an inflammatory response that may facilitate the detrimental effects of HS on animal agriculture. Identifying flexible management strategies (i.e. nutritional supplementation) to immediately decrease HS susceptibility without negatively influencing production traits would be of great value to global animal agriculture