Announcement

Plasma LH was measured by radioimmunoassay after the administration of gonadotropin releasing analogue (Gonadorelin, Hoechst) in five buffalo heifers in January and June. A longer time from injection to the LH peak and a lower LH peak height was found in June as compared with January. The difference between the two seasons in the area under the LH response curve, however, was not significant. These data suggest that the known lower ovarian activity during the summer season may be associated with a decrease in the level of pituitary activity.