In this study, we aimed to investigate the effects of different levels of boron supplementation to the diet during the close-up period and the first postpartum day on postpartum colostrum quality, immunoglobulin levels in colostrum, and certain calf blood parameters in dairy cattle (n = 21). Two experimental groups and one control (C) group were formed. Boron at 300ppm (T-300) and 600ppm (T-600) was added to the experimental rations. The daily dry matter intake (DMI), body condition score (BCS) of dairy cattle, and body weight (BW) of calves were recorded. Colostrum samples were collected during the first 2 postpartum milkings, and their components were determined. Blood samples were collected from calves at 24 and 48hours after colostrum feeding. The addition of boron to rations during the close-up dry period increased the DMI of cows and the BW of calves born to the T-600 group (p < 0.05). The addition of boron to the rations changed the total protein (TP) and nonesterified fatty acid (NEFA) values in the calf blood samples taken 48hours after birth from those of the control group (p < 0.05). The differences between the blood boron values of the experimental and control groups at 24 and 48hours after colostrum and colostrum feeding were significant (p < 0.05). At the first milking after birth, the colostrum DM value and density were highest in the T-600 group (p < 0.05). In conclusion, due to the high density value of colostrum according to the quality classification of colostrum in the first postpartum milking and the increase in calf blood IgG levels at 48 hours compared to the control group, it may be considered to add up to 600 ppm boron to the rations of cows close-up period in order to improve calf health and prevent calf losses due to colostrum quality.