Our objective was to determine if feeding transition milk (TM, milkings 2-4 after calving) during the first 4 d of life would improve health, intestinal development, and growth of calves. We conducted 2 studies. In study 1, 105 Holstein heifer calves on a commercial dairy farm were assigned to 1 of 3 diets (n=35/diet): Milk Replacer (MR), Transition Milk (pooled from several cows and pasteurized), or a 50:50 blend of Milk Replacer and Colostrum Replacer (MCR). Calves were fed 1.9 L of MR, TM or MCR 3 times per day for 3 d. After 3 d, calves were fed and managed similarly until weaning at 56 d. Treatment did not alter health scores during the first 21 days. Compared to MR, TM and MCR gained more BW by 56 d and had lower haptoglobin concentration in plasma. Utilizing equations from the NRC (2001), one third of the difference in BW gain was accounted for by caloric differences in the treatment diets. In study 2, we fed 23 Holstein bull calves MR or TM (pooled from several cows with milkings 2, 3, and 4 kept separate and not pasteurized). Calves started the study in 6 blocks, with each block containing 4 calves born within a 12-h period. Calves were fed diets 3 times per day for 4 d, given bromodeoxyuridine to label cells synthesizing DNA on d 5, and euthanized 2 h and 10 mins later. Sections of the duodenum, proximal jejunum, mid jejunum, and ileum were excised. Compared to MR, TM doubled BW gain and nearly doubled villus length, villus width, villus to crypt ratio, and mucosal length in all sections. Compared to MR, TM increased sub mucosal thickness 70% in the proximal and mid jejunum and tended to increase submucosal thickness in duodenum and ileum but did not alter crypt depth. In all sections, labeling with bromodeoxyuridine was increased 50% by TM compared to MR in the epithelium of the crypts and within the villi, indicating that TM increased cell proliferation compared to MR. TM also improved health scores for cough, fecal, nose, and ear compared to MR, but did not alter eye score. In both studies, calves fed TM gained more BW than calves fed MR. We conclude that feeding TM for 4 d after first colostrum using this feeding program improves indicators of health, development, and growth. Whether feeding extra MR to account for energy differences with TM would have achieved similar results is not clear.
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