Induction of hypocalcaemia and evaluation of reticuloruminal motility using a three-axis accelerometer

Context Reticuloruminal motility, which is continuous and regular, is essential for digestive activity, but some functional abnormalities can appear in cattle with several metabolic disorders. Particularly in periparturient dairy cows, decreased blood calcium concentrations induce deterioration of rumen motility as well as the risk of reproductive disorders. Aims This study aimed to evaluate reticuloruminal motility using a bolus-type biosensor incorporated with a three-axis accelerometer (3XA) following induction of hypocalcaemia by infusion of ethylenediamine-tetraacetic acid disodium salt dihydrate (Na(2)EDTA) solution. Methods In the 2 x 2 crossover experiment, six non-pregnant and non-lactating cows were assigned to each of the treatment (TRE) and control (CON) groups and infused for 1 h with 13% Na(2)EDTA solution and physiological saline respectively. The cylindrical biosensor was fed and placed in the reticulum before the experiment, and the three acceleration values of each cow were recorded and transmitted wirelessly. Considering the device shape, the reticuloruminal motility was represented as the vector value (V-2) calculated with each change in X- and Z-axis acceleration over time. Key results Plasma calcium concentrations were measured to confirm hypocalcaemia, and the average was significantly decreased to 1.23 mmol/L at 1 h in TRE. The mean V-2 value was significantly decreased in TRE compared with CON, from 1 to 2 h after Na(2)EDTA infusion. Conclusion 3XA was able to detect a change in reticuloruminal motility caused by hypocalcaemia. The use of 3XA in cattle will allow for rapid treatment of hypocalcaemia or other metabolic disorders that reduce productivity. Implications The 3XA inserted into the reticulum of a dairy cow detected a decrease in reticuloruminal motility wirelessly caused by induced hypocalcaemia.