[Ovulation prediction in cattle by rapid measurement of plasma LH and by laparoscopic observation].

The last hours of intrafollicular maturation are important to preserve the potential of oocytes for fertilization and development. To collect mature oocytes it is consequently essential to predict accurately the time of ovulation. Therefore we have modified a regular and specific plasma LH radioimmunoassay to a convenient assay providing reliable results within four to five hours. Using this technique we have been able to detect the LH peak with a delay small enough to predict the moment of ovulation; then we have been able to observe and photograph ovulation. The antigen-antibody reaction takes place during a two hour incubation at 37 degrees C. The immune complex is precipitated by addition of a rabbit anti-gamma-globulin and incubation at 22 degrees C for 30 minutes. The variation between fast and regular assays is lower than 15%. From a study of 25 cycles in 12 animals we suggest intervals of approximately 27 hours between the beginning of the LH peak and ovulation and of about 17 hours between the end of the peak and ovulation. Intervals between the beginning of heat and ovulation appear irregular and cannot be used with certainty as a reference point to predict ovulation. Five ovulations were observed closely and in the five cases, the formation of an apex was noted Our results clearly show that with the technique mentioned above we can predict rapidly and precisely bovine ovulation.