Taurine, one of the sulfur-containing amino acids, has several functions in vivo. It has been reported that taurine acts on gamma-aminobutyric acid receptors as an agonist and to promote inhibitory neurotransmission. Milk, especially colostrum, contains taurine and it is known that milk taurine is essential for the normal development of offspring. beta-Alanine is transported via a taurine transporter and a protein assisted amino acid transporter, the same ones that transport taurine. The present study aimed to investigate whether the growth and behavior of offspring could be altered by modification of the taurine concentration in milk. Pregnant ICR mice were separated into 3 groups: 1) a control group, 2) a taurine group, and 3) a beta-alanine group. During the lactation periods, dams were administered, respectively, with 0.9% saline (10 ml/kg, i.p.), taurine dissolved in 0.9% saline (43 mg/10 ml/kg, i.p.), or beta-alanine dissolved in 0.9% saline (31 mg/10 ml/kg, i.p.). Interestingly, the taurine concentration in milk was significantly decreased by the administration of beta-alanine, but not altered by the taurine treatment. The body weight of offspring was significantly lower in the beta-alanine group. beta-Alanine treatment caused a significant decline in taurine concentration in the brains of offspring, and it was negatively correlated with total distance traveled in the open field test at postnatal day 15. Thus, decreased taurine concentration in the brain induced hyperactivity in offspring. These results suggested that milk taurine may have important role of regulating the growth and behavior of offspring. (C) 2017 Elsevier Inc. All rights reserved.