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 mm 3 ) 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.