Failure of passive transfer of IgG is one of the major reasons for increased morbidity and mortality among neonatal calves. This is mainly due to lack of a sufficient amount of high-quality colostrum with a minimum of 50 g IgG/l to
the newborn calves. By applying a modified processing method that concentrates IgG in colostrum, the total volume of high-quality colostrum can be increased. Hence, the objective of this study was to investigate whether calves fed with concentrated colostrum within 0-2 h after birth attain a sufficient passive immunization compared to calves fed non-processed (i.e. 50 g IgG/l) colostrum. This pilot experiment included 6 newborn Holstein calves divided into 2 groups, with 3 calves assigned to control colostrum (CC) and processed colostrum (PC), respectively. Colostrum from both treatments was heat treated at 60 °C for 60 min and had an IgG concentration of 44 and 61 g/l in CC and PC, respectively. Immediately after birth calves were weighed and fed with either CC or PC (i.e. 10% of birth BW) within 0-2 h after birth using an oesophageal tube. Calves were 1.20±0.32 h old at first colostrum feeding, had a birth BW of 38.7±2.2 kg, and were fed 3.88±0.20 l of colostrum. Feeding PC compared to CC resulted in a numerically higher volume of ingested IgG pr kg birth BW (6.10±0.09 vs 4.50±0.13 g/kg birth BW), a numerically higher concentration of IgG in plasma at 69±12 h of age (34.6±5.3 vs 22.0±1.8 g/l) and a numerically higher apparent efficiency of absorption (56±9 vs 50±3%). The findings indicate that colostrum concentrated to a well-defined high-quality colostrum (≥50 g IgG/l) can be used as a substitute to high-quality colostrum. Thus, the quantity of high-quality colostrum can be increased and thereby the total rate of passive immunized newborn calves can be ensured. As the results of this pilot study look promising, further studies are currently evaluating short- and long-term effects of feeding processed colostrum to newborn calves on their passive immunity, health, and productivity.