This experiment was carried out to measure the content of lactoferrin, IgA, $IgG_1,\;IgG_2$, in Holstein colostrum, and to test the effect of it's colostrum on the antibacterial activity to pathogenic bacteria and the growth stimulation of lactic acid bacteria. Colostrum was collected at the first, second, and third day after parturition in summer and winter season. The levels of lactoferrin, IgA, $IgG_1,\;and\;IgG_2$ in Holstein cow colostrum were 0.30 mg/mL, 0.37 mg/mL, 4.00 mg/mL, 0.37 mg/mL, respectively, on the first day of the summer season whereas they were 1.16 mg/mL, 2.60 mg/mL, 13.35 mg/mL, 1.30 mg/mL on the first day of the winter season, postpartum. Heat treated ($65^{\circ}C$ for 30 min) or non-treated colostrum showed antibacterial activity toward Escherichia coli. The growth of commercial mixed strains (Bifidobacterium longum, Lactobacillus acidophilus, Streptococcus themophilus), L. acidophilus, L. casei, L. bulgaricus, and L. lactis subsp. cremoris were improved in first, second and third day colostrum compared to normal milk. Commercial miked strains (B. longum, L. acidophilus S. themophilus) lowered the pH to 4.97-5.22 and 4.89 while increasing the titratable acidity to 0.75-0.88% and 0.70% in colostrum and normal milk, respectively. However, L. casei, L. bulgaricus, L. lactis subsp. cremoris lowered the pH to 5.96-6.47 and 6.5-6.8 while increasing the titratable acidity to 0.29-0.48% and 0.20-0.25% in colostrum and normal milk, respectively.