A semiquantitative and rapid radioimmunosorbent assay of luteinizing hormone for early prediction of time of ovulation in cattle.

A radioimmunoassay (RIA) for bovine luteinizing hormone (LH) is presented. It is based on the binding of the second antibody to polystyrene vials. Less than 4 h is required to estimate the hormone level in the plasma. LH content is determined by comparing unknown plasma samples to relevant control plasma to identify the preovulatory LH surge. Of 182 samples, 176 (97%) were found to contain either more or less LH than the control plasma, and 12 out of 13 (92%) LH surges were identified using the immunosorbent RIA. The method can be used for early prediction of ovulation in cattle, and it may be used to time aspiration of oocytes.