IDENTIFICATION OF OVARIAN FOLLICLES AT ESTRUS AND DEVELOPMENT OF THEIR ENSUING CORPORA LUTEA IN SINGLE AND MULTIPLE OVULATING EWES ON TWO FEEDING REGIMES

Abstract

Twelve hours after standing estrus was first detected, 30 ewes had their four largest follicles identified and marked with India ink. Seven days later, ovulation rates and origin of the corpora lutea (CL) from previously marked follicles were determined. Feeding a high energy ration from day 10 to estrus did not change the ovulation rate as compared to feeding a low energy ration. Its only effect was to increase the diameter of the third and fourth largest follicles. The diameter of the largest follicle was identical in single and multiple ovulators. However, in multiple ovulators, the diameter of the second largest follicle was larger than in single ovulators. The largest follicle identified at estrus developed into a CL that was 15% heavier in single than in multiple ovulators. In multiple ovulators, the second largest follicle developed into a CL of weight similar to that from the largest follicle.