Comparison between the reproductive performance of ewe hoggets and mature ewes following a progesterone-based oestrus synchronization protocol

Two experiments were conducted to compare the reproductive performance of ewe hoggets and mature ewes. All ewes were synchronized by an intravaginal progesterone-releasing device and bred together over a 5-day period. In Experiment 1, of those joined with the ram, more mature ewes ovulated (99% vs 68%; P < 0.05) with a higher ovulation rate (1.82 vs 1.14; P < 0.05) than ewe hoggets. Mature ewes had a higher pregnancy rate (98% vs 47%; P < 0.05) and lower early pregnancy loss (13% vs 41%; P < 0.05) than ewe hoggets. In Experiment 2, the ovulation rate (1.84 vs 1.44; P < 0.05) and pregnancy rate (86% vs 7%; P < 0.05) was higher in mature ewes compared with ewe hoggets. Combined, these studies help to quantify the difference in reproductive performance during breeding and pregnancy between ewe hoggets and mature ewes, and help to direct further research.