Seasonal changes of some reproductive traits in Farafra ewes under Egyptian environmental condition

Abstract
Thirty Egyptian Farafra ewes were used to study the effect of seasonal variations on reproductive cycle
and ovarian activity. Estrus was detected twice daily throughout the year. Percentages of ewes showing
estrus monthly, number of estrous cycle/ewe/season, estrous cycle length and heat duration were
measured throughout different seasons of the year. Changes in ovarian activity were examined using
Laparoscopy technique. Percentage of ovulated ewes, ovulation rate and number of large and small
follicles were recorded over different seasons. The obtained results revealed that the highest active
cycles were observed in autumn and summer (87.1 and 84%), while the lowest was observed in spring
(64.3%). Percentages of ewes that exhibited normal estrous cycle length during winter, spring; summer
and autumn were 73.3, 47.0, 64.0, and 44.5%, respectively. While, the percentage of the short estrous
cycle length was high in autumn (37.0%). During spring, summer and winter, the percentages of the
long cycle length were 25.0, 20.0 and 20.0 %, respectively. The percentages of ewes showed normal
heat duration during autumn was 63.0%, summer (56.0%) and spring (46.4%), while the percentage of
ewes exhibited short heat duration were in spring (53.6%) and winter (50%). During autumn, ewes
recorded the longest (p<0.01) heat duration (64.7 hrs). Ovulation rate was the highest (P< 0.01) in
autumn (1.75) and the lowest in winter (0.82). Incidence of large follicles (2.76 > 3 mm3) in diameter
were significantly higher (P<0.05) in winter. Plasma progesterone concentration was always the lowest
at the onset of estrous, increased gradually to a maximum level in day 8 and remained until day 14 (luteal
phase), then declined in day 16 in winter, spring and summer and at day 18 in autumn. In conclusion,
subtropical Farafra ewes were almost cyclic throughout the year. Reproductive performance of Farafra
ewes still need more studies to reveal the strength and potential of this breed.