Twenty-four Holstein cows were divided into two groups blocked for age and milk yield. An 8-wk lactation study was conducted from June 22 through August 16, 1986. Corn silage was fed ad libitum and grain restricted to 1 kg/3 kg milk. One group of cows was fed silage that had been treated at ensiling (1 x l0 s cfu of Lactobacillus plantarum/g silage).