Implications for early rearing techniques: ovarian dynamic and hormonal effects in Barki Ewes

Abstract Background Compared to mature ewes, the ovarian dynamics and hormonal characteristics of ewe lambs aged 10–12 months are still poorly understood, although reproductive efficiency in sheep is essential for increasing flock productivity. To overcome this gap in knowledge, the present study aimed to compare ovarian follicular dynamics, circulating progesterone and estradiol-17β profiles, and selected parameters of reproductive efficiency between ewe lambs and mature ewes, to identify potential differences in ovarian activity and reproductive performance. Methods Sixty Barki ewes were separated into two equal groups: mature ewes and ewe lambs. At 24, 48, and 72 h after sponge withdrawal, ultrasonography and Enzyme-Linked Immunosorbent Assay (ELISA) were used to measure ovarian dimensions, follicular dynamics, serum estradiol 17-β and progesterone levels. Fertility, estrus, and lambing rates were measured after mating with fertile rams. Results The length and width of the ovary for both sides of the ovary were significantly higher in the mature ewe compared to the ewe lambs. Mature ewes had larger ovarian dimensions ( P < 0.01) and higher estradiol 17-β ( P < 0.01) when comparing the lamb ewe groups, but fertility rate was no significance ( P > 0.05). On the right side the diameter value was larger for the mature ewes than ewe lambs. Furthermore, the serum progesterone concentrations did not differ significantly ( P > 0.05) during experimental periods, although serum estradiol 17-β had a greater value in the mature ewes than ewe lambs. There were no significant differences ( P > 0.05) in fertility rates between mature ewes and ewe lambs. Conclusion Mature ewes showed ovarian activity and higher estradiol 17-β concentrations compared to ewe lambs. Furthermore, reproductive performance parameters, including fertility, estrus, and pregnancy rate, showed no significant differences between groups, indicating the use of ewe lambs (10–12 months) in breeding programs can increase flock productivity without compromising reproductive performance.