Estrus synchronization with melengestrol acetate in cyclic ewes. Insemination with fresh or frozen semen during the first or second estrus post treatment

Effect of time of artificial insemination on fertility of progestagen and PMSG treated indigenous Greek ewes, during non-breeding season

A total of 2567 indigenous Greek ewes (Chios, Vlachiki and VlachikixChios breeds) were used to determine the optimum time for insemination, following synchronization of oestrus with MAP-impregnated intravaginal sponges and PMSG during non-breeding season. Within each breed group, the ewes were divided into three subgroups and submitted to a double blind cervical artificial insemination 48 and 60h (subgroup I), 60 and 72h (subgroup II) and 48 and 72h (subgroup III) after sponge withdrawal. From the results of the present investigation it can be concluded that the conception rate in the Chios island breed is better than that in the VlachikixChios breed, with the latter being better than that in the Vlachiki breed. Using fixed time for AI, a better conception rate is obtained when applied 48 and 72h after sponge withdrawal for Chios and ChiosxVlachiki breeds, while for Vlachiki breed a better conception rate is obtained when fixed AI is applied 48 and 60h after sponge withdrawal.

A comparison of the effects of progesterone sponges and ear implants, PGF2alpha, and their combination on efficacy of estrus synchronization and fertility of Mashona goat does

Efficacy of estrus synchronization and fertility after synchronization of 60 multiparous Mashona goat does using intravaginal progesterone (P4) sponges (Group 1), norgestomet ear implants (Group 2), cloprostenol (Group 3), or a combination of P4 sponges and cloprostenol (Group 4) was compared with untreated does (Group 5). At the end of treatments, all does were mated to intact fertile bucks for 21 d. The number of does bred within 11 to 96 h was significantly higher (P < 0.05) in the treated groups than the untreated control, with rates of 80, 80, 64, 67 and 30% for Groups 1 to 5, respectively. There were no differences (P > 0.05) among treated does. Kidding rates ranged from 64 to 83% but were not different (P > 0.05) between groups. Prolificacy and overall fecundity were similar (P > 0.05) among the groups. The results indicate that all 4 treatment methods were effective in synchronizing estrus and that none of the methods affected overall fertility of the does.

Reproductive performance of lactating dairy cows following oestrus synchronisation with progesterone, oestradiol and prostaglandin

The ability to synchronise onset of oestrus, and hence the time of breeding and calving, offers potential economic and management benefits to dairy farmers, especially in herds with seasonally concentrated calving patterns. A trial involving 2681 cows in 11 seasonal herds was conducted to evaluate the reproductive performance of lactating dairy cows following oestrus synchronisation with a combination of progesterone, oestradiol and prostaglandin. Cows were randomly assigned within herds to synchronised and control groups, balanced for age, date of calving, body condition and breed. Cows in the synchronised group were treated with an intravaginal progesterone-releasing device containing 1.9 g of progesterone and a gelatin capsule containing 10 mg of oestradiol benzoate 10 days prior to the planned start of the breeding season (Day 0). The device was removed 8 days later on Day -2 and a luteolytic dose of prostaglandin F2alpha was administered 2 days prior to removal of the progesterone-releasing device. Returns to service for cows in the synchronised group were synchronised by inserting a previously used intravaginal device during Days 16-21 after the start of the breeding season. Cows in the control group were left untreated. The percentage of cows being inseminated during the first 5 days was 89.0% for the synchronised group compared to 29.7% for the control group. Compared to cows in the control group, those in the synchronised group had a lower conception rate to the first insemination (52.9% v. 64.3%, p<0.001), a lower conception rate to the second insemination (51.8% v. 62.5%, p<0.001), a higher percentage of empty cows at the end of the breeding season (7.3% v. 5.1%, p<0.05), and more insemination services per pregnancy to artificial insemination (2.0 v. 1.6, p<0.001). There was no difference between the synchronised and control groups in the percentage of cows pregnant to artificial insemination (81.8% v. 85.5%, p>0.10). The mean day of conception from the start of the breeding season was advanced (p>0.0 1) by 1.3 days in synchronised cows (19.9 +/- 0.7 days; mean +/- SEM) compared to control cows (21.2 +/- 0.5 days). It is concluded that the oestrus synchronisation regime used in the present study caused a reduction in fertility, which reduced the potential gains from using such a programme to increase reproductive efficiency in dairy cows.