Ruminal and abomasal ammonia concentrations were determined in cows with left displaced abomasum (LDA), right displaced abomasum (RDA), or abomasal volvulus (AV) before the abomasum was corrected, as well as one and three days later, and compared with those from healthy control cows fed hay or hay and concentrates. In LDA, RDA, and AV, ruminal and abomasal ammonia concentrations before correction of the position of the abomasum significantly exceeded ammonia concentrations in control cows during hay diet. In LDA, ruminal and abomasal ammonia concentration before correction did not differ from control cows during hay/concentrate diet, whereas in RDA and AV, ruminal and abomasal ammonia significantly exceeded control cows during hay/concentrate diet. Ammonia concentrations significantly differed between forms of displacement before correction and one day after correction, with LDA showing lowest, RDA intermediate and AV highest ruminal ammonia values, and LDA and RDA showing lower abomasal ammonia values than AV. However, three days after correction, ruminal and abomasal ammonia concentrations did not differ between LDA, RDA and AV. Up to the third day after correction, ruminal and abomasal ammonia concentrations significantly decreased in LDA, RDA and AV. On the third day after correction, ruminal and abomasal ammonia concentrations in LDA, RDA and AV did not differ from control cows during hay diet, and were significantly lower than in control cows during hay/concentrate diet. These findings suggest disturbances in the protein metabolism of cows with abomasal displacement.