Effects of Gonadotropin Releasing Hormone and Prostaglandin F2 Alpha (α) on Postpartum Reproductive Fertility in Black Bengal Goat (Capra hircus)

Experiment 1 was conducted to compare 7 and 7 Synch and the 7-day CO-Synch + controlled internal drug release (CIDR[copyright]) protocols prior to fixed-time artificial insemination (FTAI) of beef cows with conventional or sex-sorted semen. Cows (n = 1,538) were blocked based on age and days postpartum (DPP) and randomly assigned to protocol and semen type. Cows assigned to 7-day CO-Synch + CIDR (n = 769) received administration of gonadotropin-releasing hormone (GnRH) and insertion of an intravaginal progesterone-releasing insert (CIDR) on Day -10, and administration of prostaglandin F2[alpha] (PG) coincident with CIDR removal on Day -3. Cows assigned to 7 and 7 Synch (n = 769) received PG and insertion of CIDR on Day -17, GnRH on Day -10, and PG coincident with CIDR removal on Day -3. Estrus detection aids were applied to all cows. Cows received FTAI 66 h after CIDR removal with conventional (20 x 106 cells per unit) or sex-sorted (4 x 106 cells per unit) semen. Estrus expression was affected by protocol (P = 0.01) by protocol x DPP (P = 0.0004), with 7 and 7 Synch (82 percent; 629/769) resulting in a greater proportion of cows expressing estrus (82 percent [629/769] versus 64 percent [492/769]), especially among cows with greater DPP. Pregnancy rates to FTAI were reduced (P < 0.0001) when using sex-sorted semen but greater among cows treated with 7 and 7 Synch (conventional semen: 72 percent [280/389]; sex-sorted semen: 52 percent [199/380]) compared with 7-day CO-Synch + CIDR (conventional semen: 61 percent [233/383]; sex-sorted semen: 44 percent [171/386]). Experiment 2 was designed to evaluate later timing of fixed-time artificial insemination (FTAI) with sex-sorted semen among postpartum beef cows following the 7 and 7 Synch protocol, with the hypothesis that later timing would result in increased pregnancy rates (P/AI) among cows that expressed estrus prior to FTAI. Beef cows (n=414) were blocked based on age and days postpartum (DPP) and randomly assigned to receive FTAI at 66 or 72 h after administration of prostaglandin F2[alpha] (PG). Estrus was synchrized using the 7 and 7 Synch protocol, which consists of administration of PG (500 [mu]g cloprostenol) and insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38 g progesterone) on Day 0, gonadotropin-releasing hormone (GnRH; 100 [mu]g gonadorelin) on Day 7, and PG coincident with CIDR removal on Day 14. Estrus detection aids (EstrotectTM) were applied to all cows on Day 14, and activation status was recorded at fixed-time artificial insemination (FTAI) on Day 17. All cows that expressed estrus prior to FTAI received sex-sorted semen (4 x 106 cells per unit; SexedULTRA 4MTM). The proportion of cows expressing estrus prior to FTAI did not differ between treatments at this power of test (66 h: 71 percent [146/205]; 72 h: 76 percent [158/209]). Additionally, P/AI of estrous cows inseminated with sex-sorted semen did not differ between treatments (66 h: 45 percent [68/146]; 72 h: 40 percent [63/158]). In conclusion, later timing of FTAI following the 7 and 7 Synch protocol failed to improve P/AI of estrous cows inseminated h sex-sorted semen.

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116 EFFECT OF EXOGENOUS PROGESTERONE AND GONADOTROPIN-RELEASING HORMONE APPLICATION ON MAINTENANCE OF PREGNANCY IN EARLY PREGNANT EWES AFTER PROSTAGLANDIN F2 ALPHA INJECTION

Reproduction Fertility and Development ◽

10.1071/rdv27n1ab116 ◽

2015 ◽

Vol 27 (1) ◽

pp. 150 ◽

Cited By ~ 1

Author(s):

M. Kose ◽

M. S. Kaya ◽

M. O. Atli

Keyword(s):

Early Pregnancy ◽

Prostaglandin F2α ◽

High Plasma ◽

Gonadotropin Releasing Hormone ◽

Plasma Progesterone ◽

Releasing Hormone ◽

Prostaglandin F2 Alpha ◽

Buserelin Acetate ◽

Chi Squared ◽

Exogenous Progesterone

In this experimental study, we tested the hypothesis that exogenous progesterone and GnRH applications would prevent the detrimental effect of prostaglandin F2α (PGF2α; a) on early pregnancy in ewes by sustaining high plasma progesterone level. For this purpose, 9 pregnant ewes (mating day = 0) were divided into 2 groups on Day 18 as follows: (1) PGF2α group (125 μg of d-cloprostenol injection on Day 18, n = 5); (2) PGF2α + progesterone sponge group (125 μg of d-cloprostenol injection on Day 18 + 20 mg flugestone acetate for 7 days, n = 4). Moreover, gonadotropin-releasing hormone (GnRH; 10 μg of buserelin acetate, n = 4) was injected intramuscularly to PGF2α + progesterone sponge group ewes on Day 22 after mating to induce luteinization in dominant follicles. The progesterone sponge was withdrawn on Day 25. Plasma progesterone (P4) concentration was measured on Days 18 and 19 by ELISA. Pregnancies were examined by using transrectal ultrasonography on Days 18, 22, 25, and 35 after mating. Statistical difference between groups was analysed by Chi-squared test. P4 concentration declined to below 1 ng mL–1 on Day 19 in both groups. While all pregnancies were terminated (5/5) in the PGF2α group by Day 25, progesterone sponge application prevented pregnancy loss (4/4) in the PGF2α + progesterone sponge group (P < 0.02). When the progesterone sponge was withdrawn on Day 25, half of the pregnancies (2/4) continued after GnRH application in the PGF2α + progesterone sponge group until birth. In conclusion, results suggest that exogenous progesterone application is sufficient for maintaining early pregnancy in ewes, even if the corpus luteum is regressed. Furthermore, GnRH application on Day 22 after mating might luteinize dominant follicles and could be sufficient to maintain pregnancy after exogenous progesterone is removed.

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