Abstract Thirty-six Holstein calves, 2 to 4 d of age, were randomly divided into two groups to determine the effect of curd development on abomasal retention times and estimated passage rates of different milk replacer components. One milk replacer based on low heat skim milk powder was formulated to contain 25.8% CP and 21.1% fat. Casein coagulation was prevented in one case by precipitating Ca++ with an oxalic acid-sodium hydroxide buffer solution added to the reconstituted diet. The abomasa of all animals were removed following anesthesia, and the contents were measured and analyzed for fresh matter, DM, CP, and fat. For both the control and treated calves, measurements wee made on two animals before feeding time and on four animals at 1, 2, 4, and 6h postfeeding. Abomasal curd development resulted in significantly higher retention values of DM, CP, and fat at 1,4, and 6h postfeeding than when curd was prevented. At 2h postfeeding, curd development tended to result in higher CP and fat retention but DM retention was lower than in the absence of curd formation. Estimated cumulative flow over 6h postfeeding of DM, CP, and fat, expressed as percentage of intake, was higher for the treated group than for control, which was not the case for fresh matter. The technique developed in the present work may have advantages over usual cannulation techniques because physiologically intact animals are used.