Effects of Long and Short-Term Progestagen Treatments Combined with PMSG on Oestrus Synchronization and Fertility in Awassi Ewes during the Breeding Season

Abstract

Synchronization of oestrus has been used to increase reproductive effi ciency in most animals, including ewes. The aim of the present study was to compare the effect of the length of a progestagen treatment (12 d vs. 6 d) on synchronization effi ciency (oestrus response, time to onset of oestrus and duration of oestrus) and fertility rate using fl uorogestone acetate (FGA) progestagen sponge treatment with pregnant mare serum gonadotropin (PMSG) administration applied at different times of sponge removal. Ewes (n = 68) were divided into two groups; long term (LT, n = 33) and short term (ST, n = 35) groups treated with FGA progestagen sponges. At the end of intravaginal sponge treatment period the animals of each group were divided into the 3 subgroups in relation to time of PMSG (300 IU) treatment. PMSG treatment was applied 24 h before sponge removal, at sponge removal and 24 h after sponge removal for LT1 and ST1, LT2 and ST2, and LT3 and ST3, respectively. Each ewe was inseminated intra-cervically twice with skim cow milk-diluted semen (1000 × 10 6 motile cells/ml) 40 h and 60 h after sponge removal. Non-return rates (NRR-30) were monitored from 12 day after sponge removal to 30 day with the aid of teaser rams. Onsets of oestrus response and oestrus cessation were signifi cantly different (P < 0.05) between the ST and LT treatment groups. Synchronization of oestrus was tighter in LT than ST group. Except for oestrus cessation, other indicators studied were not different in the ST subgroups. In the ST subgroups the oestrus cessation of the ST1 (88.7 ± 15.4 h) was the shortest and differed from ST3 (120.0 ± 14.2 h) (P < 0.05). No statistical difference was observed among all studied indicators for LT groups according to application time of PMSG (P > 0.05). The NRR-30 and lambing rate of the ST and LT after timed AI were 35.7% and 31.0% and 32.1% and 28.6%, respectively (P > 0.05).

Oestrous synchronisation and pregnancy rate following artificial insemination (AI) in South African indigenous goats

“…The low pregnancy rate in this study might also be attributed to semen cryopreservation, as the sperm cell motility used for AI was B40% post-thaw. Pregnancy rate of 34.3% for the long-term progestagen treated does was also lower compared to the pregnancy rate of 46.7% reported by Motlomelo (Vinoles et al 2001;Greyling et al 2002;Ustuner et al 2007;Tibary 2009). Three does in this trial did not show any signs of oestrus following treatment (two unimproved indigenous goats and one Boer goat).…”

Effect of Different Doses of PMSG for Synchronisation of Estrus in Progesterone Primed Goats

“…The growth rate of follicle per day was 0.50 mm in group I and 0.90 mm in group II ( Ustuner et al, (2007) who also reported estrus response of 100 per cent, using progesterone intravaginal sponges and PMSG treatment. Thus the addition of PMSG induced estrum in all the does in group II and group III, irrespective or the dose levels used.…”

Estrus Synchronization and Artificial Insemination with Fresh and Chilled Semen in Assaf Ewes

“…Ovulatory response was rather fast, maybe due to the administration of 750 IU/ewe. eCG has been shown to reduce the interval between sponge withdrawal and estrus and improve the efficiency of synchronization of estrus and ovulation during the breeding season [38]. However, fertility rate tends to be maximum when AI is performed at the second half of the estrous, a few hours before ovulation [39].…”