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The aim of the present study was to investigate the effect of breeding season [late spring (LSP) vs winter (WIN)] on reproductive performances, foetal development and progesterone (P(4)) concentrations of sheep in the subtropics. Ewes of Farafra breed were exposed for mating in LSP (n = 79) and WIN (n = 45). Ultrasonographic examinations were performed at days 25, 45 and 75 of mating to estimate the pregnancy rate, incidence of twinning and percentage of foetal losses. Foetal growth rate was determined at 10-day interval, and blood samples were taken on days 0 (oestrus), 8, 18 of oestrous cycle and on days 30, 45, 60 and 90 of pregnancy for P(4) analysis. The results showed that pregnancy and lambing rates were greater (p < 0.01) for ewes mated in LSP (93.7% and 92.4%) than for those mated in WIN (75.6% and 71.1%), respectively. There was no effect of season on the incidence of twinning (overall 19.1%) or the frequency of foetal losses (overall 7.3%). Transient reduction of placental size, foetal growth and P(4) concentration was observed following LSP matings. In conclusion, pregnancy and lambing rates were higher following LSP matings. Summer heat stress of the late spring mated ewes transiently interferes with foetal growth and P(4) concentrations.

This study aimed to evaluate three regimes for oestrus and ovulation synchronization in Farafra ewes in the subtropics. During autumn, 43 ewes were assigned to (i) controlled internal drug releasing (CIDR)-eCG group, treated with CIDR for 12 days and eCG at insert withdrawal, n=13; (ii) PGF2alpha-PGF2alpha group, treated with two PGF2alpha injections at 11 days interval, n=14; and (iii) GnRH-PGF2alpha-GnRH group, treated with GnRH, followed 5 days later with PGF2alpha and 24 h later with a second GnRH, n=16. Oestrus-mating detection was carried out at 4 h intervals starting on day 0 [the day of CIDR withdrawal (CIDR-eCG group), the day of second PGF2alpha treatment (PGF2alpha-PGF2alpha group) and the day of PGF2alpha treatment (GnRH-PGF2alpha-GnRH group)]. Ovarian dynamics was monitored by ultrasound every 12 h beginning on day 0 and continued for 4 days. Blood samples were obtained daily for progesterone (P4) and oestradiol 17beta (E2) estimation starting on day 0 and continued for 4 days. The obtained results showed that, oestrus expression, ovulation and conception were greater (p<0.05) in CIDR-eCG and PGF2alpha-PGF2alpha groups than in GnRH-PGF2alpha-GnRH group. All ewes of PGF2alpha-PGF2alpha group presented, on day of second PGF2alpha injection with mature CL (P4>2.0 ng/ml), compared to 42.9% in GnRH-PGF2alpha-GnRH group (p=0.01). The peak of oestrus occurred 32-52, 48-60 and 28-96 h after the end of treatment in CIDR-eCG, PGF2alpha-PGF2alpha and GnRH-PGF2alpha-GnRH groups, respectively. Ovulation started 48 h after treatment in all groups and extended for 24, 36 and 48 h for CIDR-eCG, PGF2alpha-PGF2alpha and GnRH-PGF2alpha-GnRH groups, respectively. Results demonstrated that oestrus and ovulation synchronization could be efficiently achieved in Farafra ewes using either CIDR-eCG or PGF2alpha-PGF2alpha regimes; however, the GnRH-PGF2alpha-GnRH treatment induced a more spread oestrus and ovulation that may make the protocol inadequate for timed artificial insemination.

The aim of this study was to evaluate reproductive performance traits of Chios and Farafra sheep. Eight hundred and twenty five Farafra and two hundreds and five Chios ewes were used for comparison during the experimental period. Ewes lambed per ewe joined (EL/EJ), estimates of lambs born per ewe joined (LB/EJ), lambs weaned per ewe joined (LW/EJ), kilogram born per ewe joined (KB/EJ) and kilogram weaned per ewe joined (KW/EJ) were recorded and calculated. Results showed that EL/EJ in Farafra ewes was significantly (P< 0.01) higher than Chios ewes (0.67 vs. 0.49).