Does my steak have a drinking problem?

Abstract

RATIONALE: Bovine respiratory disease (BRD) results in over one billion dollars in losses to the beef production industry each year. This disease, commonly referred to as “shipping fever,” involves bovine respiratory syncytial virus and Mannheimia haemolytica infection. Such losses create a food security issue to consumers in the United States as the decrease in meat production negatively impacts human nutrition through decreased availability and increased cost. BRD is primarily a disease of confined animal feeding operations. A significant increase in BRD has been observed in recent years. In conjunction with increased BRD is a significant increase in the use of adjunct feed additives derived from corn bioethanol fuel production wastes. These wastes are commonly known as “wet cake” due to the fact that they are rapidly removed from bioethanol plants and marketed to feedlot operators before the product rots. During times of high corn prices and drought, wet cake is used universally and as a high percentage of the feed. Similar to humans, cattle will readily consume alcohol. It has been established clinically that humans who abuse alcohol are at increased risk for lung viral and bacterial infections. One mechanism for this increased susceptibility to lung infection is alcohol-induced ciliary dysfunction (AICD) whereby innate lung defense through the action of mucociliary transport is desensitized, resulting in failure to properly clear pathogens from the airways. METHODS and RESULTS: Because the bovine model has been established as an in vitro system for identifying the mechanisms of AICD, we hypothesize that BRD is exacerbated when cattle are fed alcohol in their diet because of impaired clearance due to AICD. To test this hypothesis, we collected feedlot samples of wet cake and assayed the ethanol concentration using gas chromatography. We measured cilia beat frequency (CBF) and protein kinase A (PKA) activity in ciliated primary bovine bronchial epithelial cells acquired from feedlot-sourced cattle. We observed that wet cake obtained from several feedlots contained a significant concentration of ethanol (5-27%, n=6). When ciliated bovine bronchial epithelial cells were exposed for 18 hr to 100 mM ethanol, AICD was observed in response to stimulation with 10 nM procaterol. Likewise, procaterol-stimulated activation of PKA was desensitized by alcohol pretreatment in ciliated cells derived from feedlot cattle. CONCLUSIONS: These data suggest that alcohol exposure is a potential risk factor that negatively affects innate lung mucociliary defense, potentially leading to increased incidence of BRD and decreased domestic animal meat production.