Seasonality of oestrus, ovulation and ovulation rate of Sicilo‐Sarde sheep

Abstract

This study aimed to investigate monthly changes in oestrus and ovulatory activity of Sicilo-Sarde sheep. Experimental animals comprised 25 adult and 10 maiden ewes at the start of the experiment. For 12 consecutive months (September-August), the females were exposed to natural photoperiod and permanently kept in presence of seven aproned rams. Oestrus was checked daily and ovarian activity was monitored by monthly endoscopies during the last week of each month. Ovulation rate for a particular month was assessed as the sum of corpora lutea or corpora albicans present on both ovaries at the time of endoscopy. Proportions of ewes observed in oestrus at least once a month were lowest in March (24.3%) and highest in June and October (100%). They tended (p < 0.06) to be different according to age, dropping during summer from a common value of 100% in June to 85.7% and 90% in July and then to 57.1% and 70% in August for, respectively, the Adults and Maiden females. Overall, the experimental period, 92.5% and 83.8% of Adult and Maiden ewes ovulated at least once per month (p < 0.01) respectively. Least proportions ovulating, attained 60% and 30% in April for, respectively, Adult and Maiden ewes before peaking up at 100% again in May (p < 0.05). Mean (±SD) ovulation rate of Sicilo-Sarde sheep is 1.40 ± 0.503. Adult females had a higher (p < 0.001) ovulation rate than Maiden sheep with respective average values of 1.51 ± 0.516 and 1.16 ± 0.373. It varied little between months and decreased in Adults from a maximum value of 1.95 in October to a minimum value of 1.16 in April. It is concluded that benchmarking seasonal variations of reproductive activity in Sicilo-Sarde breed would be valuable in designing improved management calendars for this breed.

Ovary morphology in ewes in different months of year

“…Проведене дослідження також показа ло, що лапароскопічний огляд яєчників є ін фор мативним прийомом вивчення особливос тей їх морфології у перехідний період, оскільки при цьому є можливість повторити огляд через певний час [15], а також ви яви ти дрібні особливості, недоступні при сонографіч ному обстеженні [12], зокрема білі плямки.…”

Non-genetic sources of variation of milk production and reproduction and interactions between both classes of traits in Sicilo-Sarde dairy sheep

“…This result confirmed finding of Atti (2011) who suggested summer mating to ameliorate reproductive performances of sheep. Indeed in June, more ewes are spontaneously cycling than in previous months (Lassoued et al, 2014). The IML varied between years of mating from 158.2 days in 2010 to 170 days in 2005 as shown in Table 3.…”

“…Generally, mating is scheduled once per year and coincides with the natural breeding season during latesummer and autumn. However and in order to synchronize the milking period with the green season (Djemali et al, 1995), the mating season in flocks included in this study is advanced to spring, out of the natural breeding season (Lassoued et al, 2014). It lasts from 2 to 3.5 months (Rouissi et al, 2001).…”

The Role of Certain Specific Hormonal Treatments in Estrus Synchronization of Ewes: A mini Review

“…Estrus synchronization has many benefits, including introducing the largest possible group of ewes in the estrus stage, thus facilitating their pollination and synchronizing their births in the reproductive season [4]. The onset of estrus can be controlled and made in the first week of the season, its off-season events, and the process of ovulation events [5]. There are several widespread ways to synchronize estrus in ewes, including natural methods (Ram effect) or pharmacological methods such as Progesterone hormone, which is used in the form of vaginal sponges or injection or implantation under the skin at the base of the ears.…”