Farmers participated in the experiment on a voluntary basis. The dairy farms included in this experiment were selected in collaboration with the Netherlands Agricultural and Horticultural Association (LTO Nederland). The allocation of calves to the respective age groups (labeled as 14 and 28 d, respectively) was done by the researchers during their weekly visits on the dairy farms. The experimental design was a matrix consisting of 13 dairy farms and 8 veal farms. The experiment was executed between March 2019 and May 2020 and was approved by the Central Committee on Animal Experiments (The Hague, the Netherlands approval number 2017.D-0029). Quality of colostrum might have long-term consequences for N-IgG titers and immunity in veal calves. Our results suggest that calves transported to the veal farm at 28 d of age showed a more advanced development of their adaptive immunity than calves transported at 14 d of age. The N-IgG titers in calves at the dairy farm were negatively related to the likelihood of being individually treated with antibiotics or other medicines at the veal farm. In wk 2 and 10 at the veal farm, N-IgG in calves was positively related to N-IgG in colostrum. In wk 1 and 1 d before transport, N-Ig in calves were positively related to N-Ig in colostrum. In wk 2 at the veal farm, calves transported at 14 d of age had higher N-IgG titers and neutrophil counts, but lower N-IgM and N-IgA titers, and lymphocyte counts than calves transported at 28 d. One day before transport, titers of N-IgG, N-IgM, N-IgA, and neutrophil counts were higher, and lymphocyte counts were lower in 14-d-old calves compared with 28-d-old calves. Hematological variables were assessed in calves 1 d before transport and in wk 2 posttransport. These antibodies were also measured in serum of calves 1 wk after birth, 1 d before transport, and in wk 2 and 10 posttransport at the veal farm. Natural antibodies N-IgG, N-IgM, and N-IgA against phosphorylcholine conjugated to bovine serum albumin (PC-BSA) were measured in serum of the dams 1 wk before calving and in first colostrum. Calves (n = 683) were transported to a veal farm at 14 or 28 d of age. 28 d), and of calf and dam characteristics, on immunoglobulin titers and hematological variables of veal calves. This study aimed to investigate effects of transport age of calves (14 vs.
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