Increased Fecal Ethanol and Methanol Concentration in Dairy Heifers after Grazing

To clarify fermentative alterations in the large intestine (hindgut) during grazing, fecal alcohol and volatile fatty acids (VFAs) concentrations were evaluated in 30 dairy heifers. The heifers were kept in pasture growing mixed grass herbage from spring (mid May) until October, and their rectal feces were collected periodically. Concentrations of ethanol, methanol and isopropanol were increased in runny feces at early stage of grazing, but gradually decreased thereafter, despite the fact that ethanol remained at a high level until early October. Fecal VFA concentration was barely influenced at early grazing stage; however, it showed marked decrease thereafter. Hindgut exposure of increased nutrients which escaped upper tract digestion might promote active alcoholic fermentation in the colon of the heifers, particularly during early grazing period when runny defecation happens frequently.