Corn grain preserved with ammonium isobutyrate for lactating dairy cattle

Twenty-four lactating cows were fed one of three complete rations containing dry corn, ensiled corn, or corn treated with ammonium isobutyrate in a Latin square arrangement of treatments. Two weeks were used for adjustments to rations and 3 wk for collection of data. There were no differences in average daily yield of milk or fat-corrected milk, but fat percentage of milk from cows fed ensiled corn was lower than that of those given dry corn. Fat test of cows fed treated corn was intermediate and not different from the other groups. Molar proportions of volatile fatty acids and concentrations of rumen ammonia were not different among treatments.