Peri-pubertal ovulatory events and progesterone profiles of Javanese thin-tail sheep

Abstract

Pre- and post-pubertal progesterone profiles and ovarian activity of 24 Javanese thin-tail ewe lambs were studied under research-station conditions. The results showed that immaturity of ovarian function before the animals reached puberty was characterized by the occurrence of ovulation without oestrus (66.7%), oestrus without ovulation (12.5%) and failure in some ewe lambs to maintain regular ovarian activity following their first ovulation. A high proportion (39.5%) of corpora lutea was not fully functional. Some pronounced increases in plasma-progesterone concentration were observed before first ovulation, while an ovulation observed by laparoscopy was not always followed by a marked increase in plasma-progesterone concentration. Once the animals reached puberty, the levels and the patterns of change in plasma-progesterone concentration during a cycle or in early pregnancy were similar to those commonly observed in temperate breeds.