Pregnancy outcomes are not improved by administering gonadotropin-releasing hormone at initiation of a 5-day CIDR-Cosynch resynchronization protocol for lactating dairy cows

In Vivo Follicular and Uterine Arterial Indices as an Indicator of Successful Hormonal Stimulation for Inactive Ovaries in Repeat-Breeder Crossbred Dairy Cows Using a Short-Term Progesterone-Based Programme

Simple Summary

Blood supply of female reproductive organs plays an important role in reproductive performance in cattle. Ovarian and uterine arterial indices (vascularised area) from colour Doppler imaging provided important information about ovarian activity, supporting clinical diagnoses and reproductive management decisions in female cattle. However, the information regarding the relationship between reproductive vascular indices and resumption of follicular activity after hormonal stimulation for inactive ovaries in infertile dairy cows is scarce; thus, infertile crossbred dairy cows with inactive ovaries were induced using a 5-day progesterone-based programme. Our results highlighted that repeat-breeder crossbred dairy cows with greater follicular size and follicular and uterine arterial indices underwent a resumption of ovarian activity after hormonal stimulation. Therefore, additional information on follicular and uterine arterial indices that can be helpful in predicting the resumption of ovarian activity after hormonal stimulation in inactive ovary cows can be gained by reproductive vascularisation from colour Doppler ultrasonography.

Abstract

An investigation of vascularity of ovarian and uterine arteries after hormonal treatment for inactive ovaries using the short-term progesterone-based programme had not yet been explored in repeat-breeder crossbred dairy cows. To investigate the in vivo follicular and uterine arterial indices as an indicator of successful hormonal stimulation for inactive ovaries in repeat-breeder crossbred dairy cattle, 59 cows with inactive ovaries were induced with a 5-day progesterone-based protocol. At the completion of hormonal synchronisation, cows were divided into two groups according to the size of the largest follicle (LF) on their ovary: small (≤10.0 mm) and large (>10.0 mm) LFs. Vascularities of LF and uterine artery (UtA) were evaluated using a colour Doppler tool. Cows that presented with large LF had greater follicular and UtA vascular indices (p < 0.001) and pregnancy rate (p < 0.01) than cows bearing small LF on their ovary. There was a positive correlation (p < 0.001) between follicular size and LF and UtA vascular indices. Our findings highlighted that in vivo LF and UtA vascular indices at the completion of hormonal stimulation might be a promising indicator for predicting success in ovarian response to hormonal stimulation for inactive ovaries of infertile crossbred dairy cows.

The effect of GnRH administration/insemination time on follicular growth rate, ovulation intervals, and conception rate of Nili Ravi buffalo heifers in 7 -day-CIDR Co-synch

The present study aimed to compare two different insemination times (72 vs 84 h) associated with an ovulation induction (GnRH) in a 7-day CIDR Co-synch to improve the conception rate of Nili Ravi buffalo heifers. Forty Nili Ravi buffalo heifers were randomly separated into two treatments based on artificial insemination (AI) timing (72 vs 84 h). All heifers were subjected to controlled internal drug release (CIDR), containing 1.38 g of progesterone for 7 days. On CIDR removal, both treatments received 150 µg of prostaglandin intramuscularly. In 7-day CIDR Co-synch (n = 20), animals were injected 100 µg of GnRH administration intramuscularly and inseminated concurrently at 72 h after CIDR removal. The remaining half (n = 20) were injected and inseminated concurrently at 84 h of CIDR removal. Pregnancy diagnosis was performed on day 40 of timed artificial insemination (TAI) with ultrasound. The follicular growth rate between 72 h after PGF_2α/CIDR removal to pre-ovulatory follicle in 7-day CIDR Co-synch was more (0.102 ± 0.005 mm vs 0.079 ± 0.003 mm; P = 0.01) at 84 than 72 h. The interval from GnRH administration/TAI to ovulation was high (26.8 ± 1.64 h vs. 15.1 ± 1.25 h, P = 0.01) in 72 than 84 h. Conception rates were considerably higher in buffalo heifers inseminated at 84 h (65%) than 72 h (25%) in 7-day CIDR Co-synch protocol. In conclusion that in Nili Ravi buffalo heifers, GnRH administration/TAI after 84 h of CIDR removal allows greater follicular growth rate and shortens interval from AI to ovulation compared to the GnRH administration/TAI after 72 h of CIDR removal in 7-day CIDR-Co-synch protocol.

Effect of One-Day Delaying CIDR Administration in 5-Day Cosynch Protocol in Dairy Heifers

Simple Summary

In modern dairy farms, the optimum age for first calving is 23 to 25 months, to achieve this goal heifers having to conceive at 15 months of age using fixed-time artificial insemination. Despite the difference of follicular dynamics between heifers and cows, the dairy cow based synchronization protocols need to be modified for dairy heifers. We investigated the effect of one-day delaying administration of intravaginal progesterone device (CIDR) at the beginning of 5-day Cosynch protocol. Pregnancy per AI (P/AI) was significantly declined in CIDR-4 (4-day CIDR application instead of 5 days) group as heifers’ age proceeded. We have shown that there was no benefit of one-day delay of CIDR administration in 5-day Cosynch protocol on P/AI. However, higher P/AI in 5-day CIDR synchronization in aged heifers could reveal the necessity of longer progesterone administration in Cosynch protocol for better fertility.

Abstract

Effect of one-day delaying progesterone administration at the beginning of 5-day Cosynch protocol was investigated in Holstein heifers for the first artificial insemination (AI). Heifers received a synchronized ovulation and timed AI (TAI) with CIDR inserted on day (d) 0 (CIDR-5; n = 206) or d 1 (CIDR-4; n = 192). In both group, GnRH was administered on d 0 followed by a single PGF_2α injection and CIDR removal five days later from GnRH. On d 8, TAI and GnRH administration were concurrently conducted. Heifers detected in estrus up to 24 h prior to TAI were inseminated without GnRH administration. Rates of ovulation, accessory CL formation and new dominant follicle development following initial GnRH injection did not differ between groups. P/AI did not differ between CIDR-4 (44.3%, [85/192]) and CIDR-5 (51.9%, [107/206]) groups, respectively. Pregnancy per AI (P/AI) was significantly (p < 0.01) declined as heifers’ age (12–13, 14, 15, 16 and17–21 months) proceeded in CIDR-4 group (55.6%, 52.1%, 37.9%, 35.7%, 32.4%) compared to those in CIDR-5 group (60.0%, 50.0%, 53.9%, 51.5%, 46.2%) respectively. In conclusion, there is no benefit for delaying CIDR administration in 5-day Cosynch protocol in dairy heifers. However, higher P/AI in CIDR-5 group in older heifers can be considered for reproductive management.

Effect of progesterone supplementation in a resynchronization protocol on follicular dynamics and pregnancy success

The objective of this study was to evaluate the necessity of a controlled internal drug releasing device (CIDR) in a fixed-time AI resynchronization protocol as well as to compare a commercially available blood pregnancy test with transrectal ultrasonography for Day 28 pregnancy detection. Over a two-year period, beef cows and heifers from twelve herds were inseminated using the 7-day CO-Synch + CIDR protocol. On Day 21 following the first insemination, the protocol was repeated, with animals receiving either a CIDR or no CIDR. Pregnancy status (AI1) was determined on Day 28 by both transrectal ultrasonography and the IDEXX Rapid Visual Pregnancy Test. Non-pregnant animals by both methods (CIDR: n = 190 cows, n = 228 heifers; no CIDR: n = 185 cows, n = 223 heifers) received an injection of Prostaglandin F2alpha and were inseminated at the appropriate time or bred following detection of estrus. Corpora lutea (CL) number and largest follicle diameter were recorded on a subset of non-pregnant animals (CIDR: n = 66 cows, n = 46 heifers; no CIDR: n = 76 cows, n = 41 heifers) at time of pregnancy diagnosis on Day 28. Final pregnancy status was determined a minimum of 31 days following the second AI (AI2). The GLIMMIX procedure of SAS was utilized for estrus and pregnancy data; while the MIXED procedure was utilized for analyses of CL number and largest follicle diameter. There was no effect (P ≥ 0.55) of treatment on AI1 pregnancy, AI2 pregnancy, or overall pregnancy rates. The presence of a CIDR during the resynchronization increased (P < 0.001) estrus expression prior to AI2. There was an effect of treatment by age on AI2 pregnancy (P < 0.01); heifers that received a CIDR had greater AI2 pregnancy rates than heifers that did not receive a CIDR (P = 0.04), but there was no difference between cows with and without a CIDR. Treatment had no effect (P > 0.10) on embryonic loss (between the first and second pregnancy diagnosis), CL number, or follicle diameter. Although, there was a tendency for the interaction of treatment by age on follicle size (P = 0.07), with cows having larger follicles than heifers in the no CIDR group but not the CIDR group. In conclusion, use of a CIDR in this resynchronization protocol increased estrus expression, increased AI2 pregnancy for heifers, but did not improve pregnancies in cows, and did not influence overall pregnancy or embryonic loss.

Development of the Timed Re-Insemination (TRI-synch) program re-inseminating 24 days after the initial service in dairy cows

For the timed re-insemination at the minimal interbreeding interval, cows were treated with a progesterone (P4 )-releasing intravaginal device from Days 13-15 to 21 post-insemination (Day 0 = estrus), followed by plasma P4 assay on Day 23 and then subjected to the Experiments 1 and 2. In Experiment 1, of 18 cows, 6 cows were determined as luteolysis with low (<1 ng/ml) plasma P4 concentrations on Day 23 and ovulated on Days 24 (3 cows), 25 (1 cow), and 26 (1 cow) except a cow affected by ovarian quiescence. In Experiment 2, all cows were treated with GnRH on Day 23. Cows with low (<1 ng/ml) plasma P4 concentrations on Day 23 were diagnosed as non-pregnant and subjected to the re-insemination in the morning of Day 24 irrespective of estrous signs. Of 36 cows, 15 cows were diagnosed as being non-pregnant on Day 23. Fourteen cows of the non-pregnant animals were re-inseminated in the morning of Day 24 irrespective of estrous signs and the pregnancy rate of re-insemination was 36%. The conception rates of initial and re-inseminations were 50% (18/36) and 36% (5/14), respectively. The overall pregnancy rate by adding the rates of initial and re-inseminations was 64% (23/36).

A shortened resynchronization treatment for dairy cows after a nonpregnancy diagnosis

We hypothesized that a shortened version of a modified Ovsynch program (OVS: GnRH-1 - 7 d - PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI) that excluded GnRH-1 to resynchronize ovulation in cows bearing a corpus luteum (CL) after a non-pregnancy diagnosis (NPD) or including progesterone supplementation with the OVS treatment for cows without a CL would produce shorter inter-insemination intervals and pregnancy per AI (P/AI) not different from that of cows treated with the OVS treatment. Of the 1697 lactating Holstein cows enrolled in this experiment, complete data were available for only 1584 cows because the remainder was not treated, inseminated per treatment design, left the herd before pregnancy diagnosis, or some other outcome was missing. Cows were enrolled in the study and assigned to either of three treatments at NPD (32 ± 3 d after AI [Day 0]). Cows with a detected CL were assigned randomly to: (1) a modified Ovsynch (OVS; GnRH-1 - 7 d - PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI) or (2) Short Synch (SS; PGF_2α-1 - 24 h - PGF_2α-2 - 32 h - GnRH-2 - 16 h - AI). Cows with no CL were assigned to OVS plus a progesterone insert (CIDR). Blood was collected at NPD to measure progesterone concentration and determine accuracy of treatment assignment (progesterone ≥ 1 ng/mL for a functional CL). Overall progesterone concentration at NPD was less in OVS + CIDR cows (1.5 ± 0.3 ng/mL) than in OVS (5.2 ± 0.2 ng/mL) or SS cows (3.7 ± 0.3 ng/mL). No differences in luteolytic risk (progesterone < 0.5 ng/mL at 72 h after PGF_2α-1) were detected after PGF_2α (>96.7%) and ovulation risk after GnRH-2 was 93.8, 91.7, and 86.2% for SS, OVS, and OVS + CIDR, respectively. Mean and median inter-insemination interval were less in SS (mean = 34.3 ± 0.05 d [median = 35 d] than OVS cows (40.2 ± 0.05 d [42 d]), but that in OVS cows did not differ from OVS + CIDR cows (41.4 ± 0.05 d [42 d]). Technicians were more accurate in visually detecting a functional CL than a non-functional CL (81.2 vs. 61.1%). Sensitivity of detecting a functional CL by technicians averaged 91.2%, but specificity was 39.8%. Pregnancy per AI at 32 ± 3 d after AI was less for SS (16.5% [n = 115]) than OVS (29.3% [n = 133] when a functional CL was inaccurately detected, but did not differ when a functional CL was detected accurately (27.6% [n = 561] vs 30.3% [508]). Pregnancy per AI did not differ between OVS and OVS + CIDR cows regardless of CL status. Short synch is an alternative to the entire modified Ovsynch program to produce similar P/AI when the CL status was detected accurately, and regardless of functional CL status, SS reduced inter-insemination intervals by 7 d.