The main objective of this study was to evaluate the effect of dietary inclusion of wheat or corn as the main source of starch in prepartum diets on colostrum composition, colostrum IgG1 and IgG2 concentrations, serum IgG1 and IgG2 concentrations of calves and efficiency of IgG1, IgG2 and total Ig absorption. For this purpose, thirty primiparous and twenty multiparous Holstein cows were used in a randomized complete blocks design. Cows were blocked by parity and expected calving dates and assigned to treatments at 27±2.5 d before calving. The dietary treatments contained corn or wheat grain as the main sources of starch. Blood samplesof calveswere drawn before the first colostrum feeding (0 h) at the birth and 24 h of life. The results indicated that prepartum diets had no effect on daily dry matter intake of cows. Lactose, fat and IgG2 concentrations in colostrum did not respond to dietary treatment, but protein, total solids, IgG1 and total IgG concentrations in colostrum were significantly higher for cows fed the wheat containing diet. At 24 h of age, serum IgG2 concentrations of calves were similar between the two treatments, while serum IgG1 and total IgG concentrations were significantly higher for calves fed colostrum from cows fed wheat containing diet. Prepartum starch source did not affect apparent efficiencies of IgG1, IgG2 and total IgG absorption. Briefly, the results indicated that feeding cows with the wheat containing diet in prepartum period increased colostrum quality and serum IgG1 concentrations in calves which in turn might have a positive effect on health, survival and growth of newborn calves. Manuscript profile