Effect of hypocalcemia on motility of the ruminant stomach.

The sensitivity of ruminal and abomasal contractions to hypocalcemia was evaluated in sheep. Serum diffusible calcium concentrations were determined during induction of hypocalcemia (IV infusion of Na2EDTA) and recovery from hypocalcemia (no infusion). Contractile strength of the rumen gradually decreased as serum diffusible calcium concentrations decreased; significant correlation (r = 0.75; P less than 0.001) was observed. Ruminal contractions disappeared before clinical signs of hypocalcemia were seen. Abomasal contractions were slightly reduced when serum diffusible calcium concentrations were equal to those producing ruminal stasis and clinical signs of hypocalcemia. These observations indicated that ruminal dysfunction may occur considerably before the onset of clinical signs of hypocalcemia.