Abstract Background The β–(1 → 3),(1 → 6)-D-glucan extracellularly produced by Aureobasidium pullulans exhibits immunomodulatory activity, and is used for health supplements. To examine the effects of oral administration of the β–(1 → 3),(1 → 6)-D-glucan to domestic animals, a small scale study was conducted using Holstein cows and newborn Japanese Black calves. Findings Holstein cows of which somatic cell