Induction/synchronization of oestrus and ovulation in dairy goats with different short term treatments and fixed time intrauterine or exocervical insemination system

Abstract

Two experiments were carried out on Ionica dairy goats in order to test the efficiency of: (1) short term-5-day combined progestogen-PGF2α-GnRH treatments on induction/synchronization of oestrus and fertility after natural mating in lactating goats and during the transition period (Experiment 1); (2) short term-9-day FGA-PGF2α-eCG treatments on synchronizing oestrus and ovulation (Experiment 2.1) and artificial insemination (AI) fixed time system in synchronized does (Experiment 2.2), during the breeding season. In Experiment 1, four treatment groups ( N = 24) were considered: (1) FPe-11d – control, FGA intravaginal sponges (11 days) + PGF2α (9th d) + eCG (11th d); (2) FPe-5d, FGA (5 days) + PGF2α (5th d) + eCG (5th d); (3) PFe-5d, PGF2α (D0) + FGA (5 days) + eCG (5th d); (4) GPe-5d, GnRH (D0) + PGF2α (5th d) + eCG (5th d). Goats were checked for oestrus and naturally mated. The occurrence of oestrus was 75.0, 78.3, 86.4, and 58.3% for groups 1–4, respectively, with significant differences ( P < 0.05) between groups 3 and 4. Interval to oestrus was earlier ( P < 0.05) in GPE-5d than in FPe-11d control group. There were no differences between the groups ( P > 0.05) in fertility or in prolificacy. In Experiment 2.1, 22 goats were subdivided into two treatment groups ( N = 11): (T1) FPe-11d (control), FGA (11 days) + PGF2α (9th d) + eCG (11th d); (T2) FPe-9d, FGA (9 days) + PGF2α (7th d) + eCG (9th d). Oestrus and ovulation times were monitored every 4 h; ovulation rate was also determined. The induction of oestrus ranged from 91 to 100% and all goats ovulated. Intervals to oestrus, from the onset of oestrus to ovulation, from sponge removal to ovulation, and ovulation rates were 28.2 ± 4.9 and 26.0 ± 4.0 h, 25.3 ± 9.2 and 28.9 ± 7.4 h, 53.5 ± 7.6 and 54.9 ± 7.1 h, 3.7 ± 1.6 and 2.4 ± 1.4 corpora lutea ( P < 0.05) for T1 and T2, respectively. In T2 a great abnormal ovulatory response was observed. In Experiment 2.2, 48 goats were synchronized with FPe-9d treatment and subjected to AI, performed 50 h after s.r. with frozen semen, and subdivided into 2 AI system groups ( N = 24): T3, exocervical AI (100 × 10 6 Spz/doe); T4, intrauterine AI (20 × 10 6 Spz/doe). Fertility rate was higher ( P < 0.05) in T4. It seems that short term-5-day combined progestogen-PGF2α-GnRH-eCG treatments need to be investigated for AI fixed time.