Timed artificial insemination in crossbred mares: Reproductive efficiency and costs.

Timed artificial insemination (TAI) has boosted the use of conventional artificial insemination (CAI) by employing hormonal protocols to synchronize oestrus and ovulation. This study aimed to evaluate the efficiency of a hormonal protocol for TAI in mares, based on a combination of progesterone releasing intravaginal device (PRID), prostaglandin (PGF2α ) and human chorionic gonadotropin (hCG); and compare financial costs between CAI and TAI. Twenty-one mares were divided into two groups: CAI group (CAIG; n = 6 mares; 17 oestrous cycles) and TAI group (TAIG; n = 15 mares; 15 oestrous cycles). The CAIG was subjected to CAI, involving follicular dynamics and uterine oedema monitoring with ultrasound examinations (US), and administration of hCG (1,600 IU) when the dominant follicle (DF) diameter's ≥35 mm + uterine oedema + cervix opening. The AI was performed with fresh semen (500 × 106 cells), and embryo was recovered on day 8 (D8) after ovulation. In TAI, mares received 1.9 g PRID on D0. On D10, PRID was removed and 6.71 mg dinoprost tromethamine was administered. Ovulation was induced on D14 (1,600 IU of hCG) regardless of the DF diameter's, and AI was performed with fresh semen (500 × 106 cells). On D30 after AI, pregnancy was confirmed by US. The pregnancy rate was 80.0% in TAIG and 82.3% in CAIG (p > .05). The TAI protocol resulted in 65% reduction in professional transport costs, and 40% reduction in material costs. The TAI was as efficient as CAI, provided reduction in costs and handlings, and is recommended in mares.

Impact of a progesterone-releasing intravaginal device and inflammatory reaction on ovarian activity in embryo-recipient anestrus mares.

This study aimed to correlate the inflammatory reaction (IR) caused by a progesterone-releasing intravaginal device (P4) with ovarian activity and pregnancy rate (PR) in embryo-recipient anestrus mares (to decrease the spring transitional period). 50 animals were assigned to three groups: GP4 (P4 group; n = 16), GP4OH (P4 + oxytetracycline hydrochloride and hydrocortisone sprayed onto the device; n = 14), and GNP4 (no intravaginal P4; n = 20). The administration protocol for GP4 was: Day 0, 750 mg P4 + ovarian examination by ultrasonography (US) + vaginal sample collection; Day 8, US; Day 11, P4 removal + 7.5 mg PGF2α + US + second vaginal sample collection; Days 13 to 16, US; Days 17 to 21, US + 750 IU hCG to mares with follicles 35 mm or more in diameter; Days 19 to 23 US (ovulation check); Days 24 to 28, embryo transfer + intravenous flunixin meglumine; and Days 30, US pregnancy diagnosis. The GP4OH and GNP4 mares received the same administration protocol as GP4, except that no P4 device was administered to the GNP4 group on Day 0. Although neutrophil-mediated IR occurred in the GP4 and GP4OH groups, the IR was significantly reduced in GP4OH as compared with that in GP4 (P < 0.0001). From Day 0 to Day 17, the GP4 and GP4OH mares developed a greater number of follicles per animal than did the GNP4 mares (P < 0.05), and the average diameter of the follicles was larger in the GP4 and GP4OH mares. The ovulation rates in GP4, GP4OH, and GNP4 mares were, respectively, 43.7%, 64.3%, and 30.0%, and ovulation occurred at 6.8, 6.5, and 23 days after P4 removal (P < 0.05). On Day 17, endometrial edema was verified in 50%, 64.2%, and 35.0% of the GP4, GP4OH, and GNP4 mares, and the PRs after embryo transfer were 80%, 100%, and 66.6%, respectively. Although intravaginal devices caused IR in both the device-recipient groups (P = 0.0001), IR and vaginitis had no negative impact on follicle diameter, ovulation rate, period to ovulation after the removal of P4, endometrial edema, or PR. In addition, P4 reactivated the ovarian function and the IR eliminated a large percentage of bacteria (Bacillus spp., Enterobacter spp., Proteus spp., Pseudomonas spp., and Staphylococcus spp.), especially in GP4; the application of oxytetracycline hydrochloride and hydrocortisone on the devices reduced the severity of vaginitis.