Live yeast products (LYPs) increase nutrient utilization and milk yield. The purpose of this trial was to determine if a LYP administered at 3 g/cow/d at a commercial dairy increased milk production. Cows were milked twice daily and given LYP in the total mixed ration in an OFF, ON, OFF, ON, OFF design where each ON or OFF period lasted 45 days and LYP was added during ON periods. Only data from cows with at least one Dairy Herd Improvement Association milk test each period were used in the data analyses (n = 1903). Statistics were performed using the Mixed procedure of SAS (SAS. 2015. SAS/ STAT User’s Guide: Version 9.4. Cary, NC: SAS Institute Inc.) with treatment nested within period and covariates: parity, days in milk, pen and corresponding production value in the previous control period. Overall, daily milk yield (32.3 and 33.0 kg, P =.0014) and milk protein (1.04 and 1.08 kg, P =.0006; 3.25% and 3.31%, P =.0021) for control and LYP, respectively, were greater for cows fed LYP. Therefore milk yield and milk protein yield and percentage increased with supplementation of LYP.