A diagnostic investigation followed an abortion outbreak in a group of nulliparous heifers on a 3,900-cow commercial dairy farm in upstate New York. In total, 153 nulliparous heifers aborted within a four-day span in August 2016. One week before the abortion outbreak, 2 pens of nulliparous heifers experienced an acute drop in dry matter intake after feeding of fresh green-chopped corn. The fresh green-chopped corn was harvested following rainfall after otherwise drought-like conditions. Formal diagnostic testing revealed unremarkable infectious abortion disease panels. Levels of nitrates indicating exposure were found in fetal intraocular fluid samples. A presumptive diagnosis of acute nitrate toxicosis was made via exclusion of other top differentials. Supportive treatment to manage sequelae associated with abortions included antibiotics and oxytocin. Reproductive performance and milk production were evaluated through on-farm dairy management computer software.