We tested the effectiveness of different preservatives for wet diets of cattle. We evaluated the growth of lactobacilli, clostridia, enterobacteria, molds, and yeasts in three experiments using: 1) different concentrations of citric acid (0, 1%, 2%, 3%, and 4%); 2) different preservatives (Benzoate, Propionate, Myco Curb, Sodium, Protonic Acid and AS4) diluted at 1%; and 3) preservatives Benzoate, Propionate, Myco Curb®, Sodium Acid, and Propionic Acid. The results were summarized using descriptive statistics. In experiment 1 there was a large amount of lactobacilli both in the control and in the treated groups. In experiment 2, the amount of colonies was higher than expected. In experiment 3, concentration of lactobacilli colonies increased throughout the time. Our results demonstrate that preservatives should be tested using a higher inclusion level for wet diets to reduce the number of colonies. Propionate, propionic acid, and myco-curb were efficient in controlling molds and yeasts from day 7 to 15.