The effect of four levels of sorbic acid (0, 1000, 2000, 3000 ppm of sorbic acid equivalent) applied at day 1 or 4 of storage at ambient summer or simulated winter temperatures, on nutritive value and degree of putrefaction of Streptococcus lactis fermented colostrum, was examined. Application of sorbic acid, particularly at day 1, resulted in a slowdown of the initial pH decline and a slowdown of an increase in the titratable acidity. Day 4 application maintained the pH at a desirable level throughout the storage. The pH decreased quadratically during storage when sorbic acid was applied at day 1 and linearly when applied at day 4. The pH levels were positively related to the levels of sorbic acid applied. Storage losses of lactose were higher in summer (88.2%) than in winter (32.8%) conditions; however, day 4 summer application of 2000 ppm of sorbic acid reduced losses to approximately 60%. Protein degradation decreased when the dose of sorbic acid applied was increased. Degradation of protein was lower by 13% in summer and 5% in winter in sorbic-acid-treated samples than in control samples. No changes in total nitrogen were noticed during storage. All levels of sorbic acid applied at day 4 reduced the fat breakdown during summer storage more effectively than day 1 application. During summer storage, the day 1 application of sorbic acid led to complete elimination of molds and yeasts, while the control count grew to a level of approximately 106/mL. The same day of application brought about partial, but not complete, control of molds and yeasts during winter storage. Visual characteristics and odor of stored colostrum were greatly improved by the application of sorbic acid especially during summer storage. Key words: Calf, colostrum, sorbate, residual lactose protein