CIDR Insertion Research Articles

PSV-3 Ovarian dynamics of brahman cows submitted to five-day or twelve-day progesterone-based estrus synchronization protocol

Abstract The aim of this study was to investigate the ovarian response of Brahman cows submitted to two different estrus synchronization protocols and to determine the estrus response and ovulation time. A total of 153 Brahman cows were randomly assigned to receive one of the following estrus synchronization protocols: 1) CIDR insert and an injection of prostaglandin F2α (25 mg, PGF) on Day -5 and CIDR removal with PGF on Day 0 (CIDR5; n = 77); 2) CIDR insert on Day -12 and an injection of PGF on Day -12, Day -5 and Day 0 upon CIDR removal (CIDR12; n = 76). Estrotect breeding indicator patches were placed on Day 0 and cows were artificially inseminated (AI) 12h after estrus detection; cows not detected in estrus after 96h received TAI coupled with 100 µg of GnRH. Ovarian dynamics were observed during the protocol and follicular diameter were measured every 12h after AI until ovulation. Cows synchronized with CIDR12 had increased follicular diameter (CIDR5, 10.19 ± 0.51 vs. CIDR12, 13.12 ± 0.52 mm; P = 0.01) and decreased serum concentrations of progesterone (CIDR5, 1.68 ± 0.12 vs. CIDR12, 0.81 ± 0.12 ng/ml; P < 0.01) at CIDR removal. The percentage of cows exhibiting estrus did not differ between treatments (CIDR5, 66.2 vs. CIDR12, 64.5%; P = 0.25). No difference was observed in ovulation rate (CIDR5, 94.1 vs. CIDR12, 94.1%; P = 0.6). Time of estrus expression and ovulation time after CIDR removal did not differ (CIDR5, 59.9 ± 2.3 vs. CIDR12, 61.5 ± 2.3h; P = 0.71 and CIDR5, 88.1 ± 2.6 vs. CIDR12, 90.9 ± 2.6h; P = 0.75; respectively). In conclusion, extended length of CIDR with additional PGF increased follicular diameter and decreased concentrations of progesterone but did not influence estrus response and ovulation time in Brahman cows.

519 Late-Breaking: Evaluation of the 7 & 7 Synch and Bee Synch II protocols for control of the estrous cycle among cows of varying percentage Bos indicus influence

Abstract The 7 & 7 Synch and Bee Synch II protocols for control of the estrous cycle were compared among cows with varying percentages of Bos indicus influence. Angus (n = 48), ⅛ - ¼ Brahman-influenced (n = 90), Brangus (n = 11), and ½ Brahman-influenced (n = 56) cows were blocked based on breed, age, and days postpartum and randomly assigned to treatment. Cows treated with 7 & 7 Synch (n = 104) received prostaglandin F2α (PG; 25 mg dinoprost tromethamine) and insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) on Day -17, gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) on Day -10, and PG coincident with CIDR removal on Day -3. Cows treated with Bee Synch II (n = 101) received PG coincident with CIDR insertion on Day -8 and PG coincident with CIDR removal on Day -3. Fixed-time artificial insemination was performed on Day 0 at 66 h. Ovarian ultrasound was performed on Day -3 to assess presence of corpora lutea (CL) and diameter of the largest ovarian follicle (LFD), and color Doppler was used on Day 7 to assess CL blood perfusion. A greater proportion of 7 & 7 Synch cows (P < 0.0001) had CL on Day -3 (83%; 86/104) compared with Bee Synch II cows (48%; 48/101). On Day -3, LFD did not differ among Bos indicus-influenced cows treated with Bee Synch II (12.5±0.3 mm), Bos indicus-influenced cows treated with 7 & 7 Synch (12.2±0.3 mm), or Angus cows treated with 7 & 7 Synch (12.1±0.6 mm); however, greater LFD was observed among Angus cows treated with Bee Synch II (15.4±0.8 mm). Brangus cows had greater periphery signal percentages (P = 0.02) when treated with 7 & 7 Synch compared with Bee Synch II. In conclusion, across cow of varying percentage Bos indicus influence, 7 & 7 Synch resulted in a greater proportion of cows with CL on Day -3.

Resynchronizing the first eligible estrus in dairy cattle after a prior insemination and fertility of the prior insemination after gonadotropin-releasing hormone and progesterone treatments

The hypothesis of this study tested whether application of designed treatments to synchronize estrus in nonpregnant previously inseminated lactating dairy cows increased the proportion of nonpregnant cows in estrus before early pregnancy diagnosis on Day 32 after the previous insemination (Day 0) and increase fertility of the pretreatment insemination. A progesterone insert (CIDR) and GnRH were applied to cows after insemination to resynchronize the returning estrus of cows that failed to conceive on Day 0. The combination of GnRH (Day 14) and a CIDR insert (d 17 through 24) in experiment 1 (n = 347 cows) did not increase (P = 0.13) the proportion of nonpregnant cows returning to estrus before pregnancy diagnosis, but increased (P < 0.01) the synchrony of their return by 24.4% points, and delayed (P < 0.01) that return by 2.3 ± 0.3 d compared with controls. Ovulation risk after GnRH treatment on Day 14 was only 10%. For cows that failed to return to estrus before Day 32, progesterone concentration on Days 14 and 17 were less than that in cows that returned to estrus by Day 32 and in pregnant cows. Cows that returned to estrus had larger follicles and fewer numbers of CL on Day 21 than pregnant cows and cows that failed to return to estrus, but concentrations of pregnancy-associated glycoproteins on Day 28 indicated that cows failing to return to estrus were likely pregnant but suffered embryo death. In experiment 2 (n = 881), use of GnRH alone (Day 7), a CIDR insert alone (Days 14 through 21), or in combination, failed to increase the proportion of nonpregnant cows in estrus before pregnancy diagnosis on Day 32 compared with controls. Cows receiving the CIDR insert had increased (P < 0.01) synchrony of estrus by 24–34% points compared with cows that did not receive a CIDR insert. More cows receiving GnRH had 2 or more CL on Days 14 and 21 compared with controls. Ovulation risk after GnRH on Day 7 was greater than 66%. In both experiments combined, treatments with GnRH or GnRH + CIDR insert increased (P = 0.015) pretreatment pregnancy per AI by 7.1% points, but did not affect pregnancy loss. Although administering GnRH with or without a CIDR insert synchronized returns to estrus, treatments failed to increase the proportion of nonpregnant cows reinseminated before pregnancy diagnosis, but increased pretreatment pregnancy risk.

Progesterone supplementation in Holstein heifers subjected to cooling and timed AI during summer: physiological and reproductive variables and thyroid hormone concentrations.

Our aim was to evaluate the effects of progesterone supplementation after fixed-time artificial insemination (FTAI) on physiological and reproductive variables and serum thyroid hormone concentrations of cooled Holstein heifers during a hot summer season. Sixty-nine Holstein heifers were randomly assigned to three treatments: (1) heifers under visual estrus detection and inseminated according to AM-PM rule (n = 23; control (C)), (2) heifers subjected to FTAI after estrus synchronization using a CIDR insert (n = 24; FTAI group), and (3) heifers treated as the FTAI group plus progesterone supplementation between the day 4 and 14 post-insemination with a reused CIDR device (n = 22; FTAI+SP4 group). All heifers were cooled daily with misting and fans. Physiological variables were measured; likewise, blood samples were collected to determine serum progesterone, thyroxine, and triiodothyronine concentrations. Both respiration rate and rectal temperature were similar among treatments. Conception rate was greater (P < 0.05) in C (65.2%) and FTAI+SP4 (59.1%) heifers than in FTAI heifers (33.3%). Serum triiodothyronine and progesterone concentrations of FTAI+SP4 heifers were similar to those of C heifers but greater (P < 0.05) than those of FTAI heifers. In conclusion, progesterone supplementation post-insemination increased conception rate and serum progesterone concentrations without affecting thermoregulation capacity in Holstein heifers subjected to FTAI and cooling during a hot summer season.

Prostaglandin F2? as ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome

This study evaluated the effect of a prostaglandin F2? (PGF) analogue as an ovulatory stimulus in dairy cows and buffaloes raised in the Amazon biome. To this end, three experiments were performed in the state of Rondônia, located in the Amazon biome. In Experiment 1, 22 lactating dairy buffaloes received 2 mg of intramuscular (I.M.) estradiol benzoate (EB) on day 0 and an intravaginal progesterone-releasing device (CIDR) from day 0 to day 9 of the protocol. On days 8 and 9, all cows were given 500 ?g of I.M. d-cloprostenol (PGF analogue). On day 10, buffaloes were divided into two groups to receive 500 ?g of PGF (PGF group, n = 8) or no treatment (CTL group, n = 14), respectively. In Experiment 2, 16 lactating crossbred dairy cows (Holstein x Gir) received 2 mg of EB on day 0 and a CIDR insert from day 0 to day 8. On days 7 and 8, all cows were given 500 ?g of d-cloprostenol. On day 9, cows were divided into two groups to receive 500 ?g of d-cloprostenol (PGF group, n = 8) or no treatment (CTL group, n = 8), respectively. In Experiment 3, 16 lactating crossbred dairy cows (Holstein x Gir) were handled and treated similarly as in Experiment 2, although cows did not receive d-cloprostenol on day 8. Single-point outcome variables were analyzed using one-way analysis of variance (ANOVA), while proportions with dichotomous outcomes were analyzed with the chi-square test. In Experiment 1, there was no difference (P = 0.30) in the ovulation rate between groups, and, on average, 68% of the buffaloes ovulated. Moreover, the treatment did not affect the interval to ovulation (P = 0.61) nor the diameter of the preovulatory follicle (P = 0.47). As for Experiment 2, only one cow, from the PG group, did not ovulate. There were no differences between the CTL and PG groups (P = 0.69) in the moment of ovulation, which occurred in average 82 h after CIDR removal. Finally, in Experiment 3, cows treated with PGF ovulated earlier than those in the CTL group (62.5 ± 5.8 and 94.5 ± 13.5 h, respectively; P = 0.05). Collectively, these results suggest that PGF hastens ovulation in lactating dairy cows, whereas no effect was observed in dairy buffaloes.

Melatonin and CIDR improved the follicular and luteal haemodynamics, uterine and ovarian arteries vascular perfusion, ovarian hormones and nitric oxide in cyclic cows.

This study hypothesizes that melatonin with exogenous progesterone (CIDR) can improve follicular, luteal, ovarian and uterine haemodynamic of heat-stressed cows. Holstein cows (N=12) studied for two spontaneous oestrous cycles during winter then divided equally during summer into the CIDR group received CIDR for 7days and the melatonin group (Mel) received three injections of melatonin (75mg/head) at the CIDR insertion, removal and ovulation days. Blood samples were collected to assay oestradiol (E2), progesterone (P4) and nitric oxide (NO). On day 0 (Ovulation), Mel had more small follicles (p<.05), higher ipsilateral and contralateral ovarian arteries (Ov.A.) peak systolic velocity (PSV), higher ipsilateral uterine artery (Ut.A.) PSV (p=.031) and blood flow volume (BFV), also Mel elevated contralateral Ut.A. PSV and BFV (p<.0001) but lowered contra Ut.A. pulsatility index (PI, p<.0001), E2 (p<.01) and NO (p<.0001). Mel increased the corpus luteum diameter (CL, p<.001), coloured area (p<.007) and P4 (p<.0001) on day 5 and reduced them (p<.05; p<.01) on Day 14. On day 10, Mel obtained CL diameter (p<.03) and coloured area (p<.002) of spontaneous that was higher than CIDR and decreased P4 (p<.003). Mel increased CL diameter, area and coloured area and decreased them thereafter. Mel increased the ipsilateral ovarian and uterine arteries PSV and BFV before ovulation and until day 8. Mel increased P4 and decreased NO until days 6 and 14. In conclusion, the improvement in follicular, luteal, ovarian and uterine haemodynamic and the decrease of NO production proved our hypothesis Melatonin doses higher than 75mg/head is recommended to improve the heat-stressed cow's fertility.

Study of sexual behaviours with different types of estrus synchronization protocols in Boer goats.

There is still a lack of information on estrus synchronization in goats. Understanding the estrus synchronization protocols and the subsequent effects is important to improve the efficiency of assisted reproductive technologies (ARTs) and subsequently would improve the breeding procedures. This study will help in determining the most suitable estrus synchronization protocol and understand better the effect on the sexual behaviour and hormonal effects in goats. A total of 127 Boer does were used and divided into three groups with different duration of CIDR insertion intravaginally either for 14 (two groups) or 9 days (one group). Approximately 0.5 ml Estrumate® (PG) was administered intramuscularly to all groups at CIDR removal, and only groups PMSG14 and PMSG9 were administered with 200IU of Pregnant Mare Serum Gonadotropin (PMSG) intramuscularly. Estrus signs were observed at 4 h intervals and blood samples were collected for progesterone and luteinizing hormone determination. The percentage of does in estrus within 24 to 72 h post CIDR removal was significantly higher (P<0.05) in groups with PMSG compared to the group without the PMSG. The numbers of does display estrus signs within 24 to 28 h post CIDR removal were significantly higher (P<0.05) in group shorter period (9 days) compared to groups with 14 days CIDR. The P4 concentrations at 24 hours post CIDR removals and LH concentration was not significantly different (P>0.05) in all groups. The time of the LH peak in the group without the PMSG was significantly delayed (P<0.05) when compared to group 9 days CIDR and administered with PMSG. It is recommended to use the treatment for 9 days CIDR since the estrous cycle can be shortened.

PSII-29 Effects of delayed injection of prostaglandin F2α and TAI in the 14-d CIDR-PG &amp; TAI protocol in replacement beef heifers

Abstract To determine the effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG &amp; TAI protocol, 911 Angus heifers at 5 locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to 1 of 2 treatment groups: 1) PG16 (n = 452), heifers received a CIDR insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal [d 30], and a 100-µg injection of gonadotropin-releasing hormone concurrently with TAI 66 ± 2 h later; or 2) PG17 (n = 459), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal [d 31], and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 171). Furthermore, transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI was similar (P = 0.50) between treatments (48.9 vs. 52.0%, respectively). Moreover, dominant follicle diameter at PGF and TAI was similar (P ≥ 0.43) between PG16 and PG17 heifers. Pregnancy rates to TAI did not differ (P = 0.48) between treatment groups (46.4 vs. 48.9%, respectively). The results of this experiment indicate that delaying the injection of PGF from d 30 to d 31 along with TAI in the 14-day CIDR-PG &amp; TAI protocol had no effects on fertility parameters in beef heifers. In conclusion, the PGF injection and TAI in the 14-d CIDR-PG &amp; TAI protocol may be delayed, providing more flexibility in scheduling without negatively affecting fertility.

55 Effects of concentrate supplementation frequency and amount on growth and reproductive performance of Brangus heifers

Abstract A 2-yr study evaluated the impacts of supplementation frequency and amount on growth and puberty attainment of Brangus heifers. On d 0 of each year, 64 Brangus heifers were stratified by BW and age (244 ± 4 kg; 311 ± 18 d) and assigned to 1 of 16 bahiagrass pastures (4 heifers/pasture). Treatments were randomly assigned to pasture (4 pastures/treatment) in a 2 × 2 factorial design and consisted of heifers offered a soybean hulls-based supplement DM at 1.25% or 1.75% of BW delivered either daily (7X) or 3 times weekly (3X; Monday, Wednesday, and Friday). On d 56, heifers were inserted with a CIDR device for 14 d, followed by administration of PGF2α and a timed-AI+GnRH protocol on d 89. Heifers were exposed to bulls from d 89 to 167. Data were analyzed using the SAS GLIMMIX procedure. No rate × frequency interactions were detected (P ≥ 0.20). Overall ADG was greater for 7X vs. 3X heifers (P = 0.007). Daily supplementation increased (P ≤ 0.03) the percentage of pubertal heifers prior to CIDR insertion and at AI compared to 3X supplementation; however, percentage of pregnant heifers did not differ (P = 0.70). Supplementation at 1.25% vs. 1.75% enhanced the overall ADG (P = 0.02) but did not impact (P = 0.18) the percentage of pubertal heifers before CIDR insertion. After the puberty induction protocol, heifers supplemented at 1.75% of BW achieved greater puberty attainment at time of AI (P = 0.05) and final pregnancy rates (P = 0.02) than heifers supplemented at 1.25% of BW. When a puberty induction protocol was included, the percentage of pregnant Brangus heifers were not affected by supplementation frequency (daily vs. 3 times weekly) but enhanced when the supplement dry matter amount was offered at 1.75 vs. 1.25% of body weight.

The Effectiveness of Pharmacological Synchronization of the Estrous Cycle in Hinds (Cervus elaphus L.): A Pilot Field Trial.

Simple SummaryReproductive biotechnics of Cevidae species may increase valuable traits for the agricultural sector, and improve genetic diversity in relatively small farmed populations. The first step of biotechnics in terms of suitability for embryo transfer or insemination is preparation of females for proper phase of the estrous cycle. Based on available synchronization protocols applicated in red deer and domestic ruminant females we estimated the protocol for hinds in view of future routine use. Progestin analogues in the form of an insert (CIDR) or a sponge (Chronogest) and injection of equine chorionic gonadotropin (eCG; Folligon) were used on the appropriate day for inducing the estrus. The effect of synchronization was checked by measurement of progesterone (P4) and 17-beta estradiol (E2) concentration by RIA, pregnancy-associated glycoproteins (PAG)s concentration by EIA and insemination effectiveness—pregnancy rate. The better method of the estrous cycle synchronization found down to be progestin sponge and eCG based protocol in hinds considering hormone responsiveness and pregnancy rate.The aim was to estimate the effective pharmacological method of the estrous cycle synchronization by checking the effects of synchronization by measurement of progesterone (P4) and 17-beta estradiol (E2) concentration by RIA and artificial insemination. The experiment was performed at the red deer farm in Rudzie (North-East Poland; 3 year’s old). The herd (N = 14) was kept away from bulls and was divided in two groups of seven animals. In the Group I, CIDR insert (0.3 g of P4) was applicated intravaginally for 12 days; a second insert replaced the first one for the next 12 days, and next 200 IU of equine chorionic gonadotropin (eCG) was injected intramuscularly (Folligon). Estrus was expected 48 h after eCG injection. In the Group II, Chronogest sponge (20 mg of flugestone acetate) was applicated intravaginally and after 7 days replaced with second chronogest sponge for 7 days. After removing the sponge, on the same day eCG was injected and estrus was expected after 48 h. Artificial insemination was provided with frozen-thawed semen twice: 12 and 24 h after expected estrus. The peripheral blood from the jugular vein was collected each time when the inserts or sponge were applicated and 40 days after insemination. The concentration of P4 and E2 in plasma was measured by RIA. The effectiveness of insemination was monitored by pregnancy-associated glycoproteins determination and observed by the number of calves born. Two pregnancies were confirmed in Group I and five in Group II based on PAG concentration. One newborn was observed in Group I and five in Group II. Both methods of synchronization are effective in hinds based on the received profile of steroids. Although the sponge shape in case of chronogest is better comparing with CIDR, which was not completely deposited in the vagina of hind, potentially leads to bacteria inflammation, and it disturbs the rightful endocrine regulation. Moreover, pregnancy rate and hormone responsiveness were better in Group II.

Size and number of corpora lutea and serum progesterone concentrations when administering two doses of eCG in an estrous synchronization treatment regimen for dairy cattle

There was investigation of whether there were ovulations from co-dominant follicles following eCG administration. In all experiments, there was GnRH injection and CIDR insertion on day 0 (D0), CIDR withdrawal on D8, and cloprostenol administration on D8 (Exp. I and II) or D7 and D8 (Exp. III). Females in the control group were not administered any further treatment. Females in other group(s) were treated with eCG (500 IU) on Day 2 in Exp. I, Day 2 (eCG-2) or 8 (eCG-8) in Exp. II and Day 2 (eCG-2) or Days 2 and 6 (eCG-2-6) in Exp. III. Ovaries were examined using ultrasonography. In Experiments I and II, females had follicle emergence on Day 2. At the time of CIDR removal, more eCG-treated heifers (8/9; Exp. I) and cows (5/6; eCG-2; Exp. II) had co-dominant follicles compared to those in the control group (P < 0.05). Occurrence of ovulations from co-dominant for individual cows was minimal. In Experiment III, the time period from CIDR removal to estrus in cows treated with eCG-2 (68 ± 13 h) was longer compared to cows in the control (37±2 h) and eCG-2-6-treated group (38 ± 5 h; P < 0.05). There was a greater proportion of heifers having ovulations and thus greater progesterone concentration in the eCG-2-6 than eCG-2 group (P < 0.05). Administering eCG twice 4 days apart with the initial administration being two days after GnRH administration, at the time of follicle wave emergence, could induce growth of and ovulation from co-dominant follicles and enhance progesterone production in cattle.

Comparison of the 7 & 7 Synch protocol and the 7-day CO-Synch + CIDR protocol among recipient beef cows in an embryo transfer program

An experiment was designed to evaluate the effectiveness of the recently developed 7 & 7 Synch protocol to synchronize estrus among recipients prior to embryo transfer (ET). Postpartum beef cows (n = 1358) across thirteen locations were assigned to either the 7-d CO-Synch + CIDR protocol or the 7 & 7 Synch protocol prior to ET. Cows were preassigned to balanced treatments within location based on age and days postpartum, with body condition score recorded at ET. Cows assigned to the 7-d CO-Synch + CIDR protocol were administered gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin acetate) on Day 7, an intravaginal controlled internal drug release (CIDR; 1.38 g progesterone) from Day 7 to Day 14, and prostaglandin F2α (PGF2α; 25 mg dinoprost tromethamine) coincident with CIDR removal on Day 14. Cows assigned to the 7 & 7 Synch protocol were administered PGF2α (25 mg dinoprost tromethamine) coincident with CIDR insertion on Day 0, GnRH (100 μg gonadorelin acetate) on Day 7, and PGF2α (25 mg dinoprost tromethamine) coincident with CIDR removal on Day 14. Cows were observed for visible signs of estrus, with GnRH (100 μg gonadorelin acetate) administered to cows failing to express estrus during the detection period. Embryo transfer was performed approximately seven days after estrus or GnRH administration. Presence of corpora lutea (CL) was determined via transrectal palpation by a single veterinarian blinded to treatment, and embryos were transferred only to cows with palpable CL. Embryo transfer was performed using either fresh or frozen embryos, with embryo stage and grade recorded for each recipient. The proportion of cows expressing estrus was increased (P < 0.0001) among cows assigned to the 7 & 7 Synch protocol (86% [529/615] vs 76% [488/640]). The proportion of cows expressing estrus and presenting with palpable CL at ET was greater (P < 0.0001) among cows following treatment with the 7 & 7 Synch protocol compared to the 7-d CO-Synch + CIDR protocol (76% [466/615] vs 65% [418/640]). Consequently, the proportion pregnant to ET was greater (P < 0.03) following the 7 & 7 Synch protocol (40% [263/653]) compared to the 7-d CO-Synch + CIDR protocol (34% [228/664]). In summary, the 7 & 7 Synch protocol involving administration of PGF2α and treatment with a CIDR for 7 days prior to GnRH improved the likelihood of estrus expression in recipients, increased the proportion of cows eligible to receive an embryo, which resulted in a greater pregnancy rate to ET.

Treatment with prostaglandin F2α and an intravaginal progesterone insert promotes follicular maturity in advance of gonadotropin-releasing hormone among postpartum beef cows

An experiment was designed to evaluate treatments to promote ovarian follicular maturity in advance of administration of exogenous gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) for control of the bovine estrous cycle. We hypothesized prostaglandin F2α (PGF2α; 500 μg cloprostenol) followed by an intravaginal progesterone-releasing insert (CIDR; 1.38 g progesterone) would induce greater follicle size and serum estradiol at the time of GnRH administration. Postpartum cows (n = 194) in two locations were assigned to one of five treatments based on age, days postpartum, and body condition score. Cows in Treatment 1 were treated with the standard 7-d CO-Synch + CIDR protocol: administration of GnRH and CIDR insertion on Day −10, and administration of PGF2α and CIDR removal on Day −3. Treatments 2–5 were designed in a 2 × 2 factorial arrangement, with Treatment 1 included as an additional reference. On Day −17, cows in Treatments 2–5 received a CIDR insert, either with (Treatments 2 and 3) or without (Treatments 4 and 5) administration of PGF2α at CIDR insertion. On Day −10, all cows were administered GnRH, and CIDR inserts were either removed (Treatments 2 and 4) or remained in place until Day −3 (Treatments 3 and 5). Treatment with PGF2α and CIDR in advance of GnRH (Treatments 2 and 3) resulted in increased diameter of the largest ovarian follicle (P < 0.001) and increased serum concentrations of estradiol (P < 0.0005) on Day −10. In addition, variation among cows in CL status (no CL vs. a single CL vs. multiple CL) on Day −3 tended to be decreased (P = 0.08), with cows more likely to have a single CL rather than no CL or multiple CL. Lastly, the proportion of cows expressing estrus prior to fixed-time artificial insemination tended (P = 0.08) to be improved. Results support the hypothesis that administration of PGF2α and treatment with a CIDR for 7 days prior to GnRH promotes follicular maturity in advance of GnRH administration and may provide an approach by which to enhance response of postpartum beef cows to GnRH-based estrus synchronization programs.

Real-time assessment of the superovulatory effect of FSH and eCG with laparoscopy at different seasons in Akkaraman ewes.

Conventional methods for determining the reproductive performance of sheep bred either after estrus synchronization during the breeding season or after induction of estrus/ovulation during the non-breeding season take a long time and may give misleading results due to the effect of environmental factors. Laparoscopic observations allow real-time monitoring of ovarian activity around estrus or ovulation. This study was aimed at assessing the superovulatory effects of follicle-stimulating hormone (FSH) and equine chorionic gonadotropin (eCG) treatments by laparoscopy during breeding (September-November, n=12) and non-breeding (April-June, n=12) seasons in Akkaraman sheep. In both seasons, after CIDR withdrawal, the ewes were injected either with 600 IU eCG or 300 μl (20 mg/ml) FSH twice at 12 hour intervals. Plasma P4, E2 and LH concentrations were determined at the time of intra-vaginal CIDR insertion (day 0) and then at its withdrawal (day 12), followed by 3 and 6 days of eCG or FSH injections. After 3 (first observation) and 6 (second observation) days of hormone injections, laparoscopy was performed to record ovarian activity in both seasons. The eCG increased (p⟨0.05) the numbers of large follicles (first observation) and CL (first and second observations) in the breeding season compared to FSH treatment. CL, small-moderate and large follicle numbers of eCG treated ewes were higher (p⟨0.05) than those of FSH at both observations in the non-breeding season. In the breeding season, eCG treated ewes had higher (p⟨0.05) plasma P4 (3 and 6 days after hormones injections) and E2 (3 days after hormones injections) concentrations than those of FSH. In conclusion, the results of the present study indicate that treatment with eCG during the non-breeding season can support ovarian activity, and thus increase ovulation rate and plasma hormone concentrations around induced estrus/ovulation in Akkaraman ewes.

Efficacy of ovulation synchronization with timed artificial insemination in treatment of follicular cysts in dairy cows

The efficacy of five ovulation-synchronization protocols with FTAI in treatment of cows diagnosed with follicular cysts was investigated in a nonrandomized study in a single herd. Cows identified with follicular structures >25 mm on two subsequent ultrasonographic (USG) examinations 7–10 days apart (n = 552) were assigned to one of the five treatment regimens on the day of the second USG examination. Treatment regimens were Ovsynch (GnRH-7d-PGF2α-56 h-GnRH-16 h-FTAI), New-CIDR (as Ovsynch with a new CIDR insert being fitted between days 0 and 7), Reused-CIDR (as New-CIDR but the CIDR insert was previously used for 7 days in another cow), G-New CIDR (Pre-GnRH on day 0 with the New-CIDR regimen being initiated 7 days later), and RG-Ovsynch (Pre-GnRH on day 0 and then every 7 days until detection of a luteal structure upon USG examination; at that point the Ovsynch was initiated). A subset of cows was subjected to ovarian USG examination at the time of PGF2α administration, at insemination, and 8–10 days post-insemination. Progesterone-releasing ability of new and reused CIDR inserts were evaluated in cows diagnosed with severe ovarian inactivity (n = 16). The data were analyzed using logistic regression with pregnancy per AI on days 30 (P/Al 30) and 70 (P/AI 70) post-insemination were included as outcome measures. Compared with Ovsynch, RG-Ovsynch improved the P/AI 30 (OR = 2.6, P = 0.03) and the P/AI 70 (OR = 2.5, P = 0.05). New-CIDR and G-New CIDR were associated with non-significant increase in P/AI 30 (OR = 2.1, P = 0.09 and OR = 2.3, P = 0.07, respectively) and P/AI 70 (OR = 2.01, P = 0.09 and OR = 2.2, P = 0.09, respectively). Reused-CIDR was not associated with improvement in P/AI (P = 0.93 and 0.79 for P/AI 30 and P/AI 70, respectively). RG-Ovsynch had a longer diagnosis-to-FTAI interval (median 24, IQR 17,31). The dominant ovarian structures and the presence of a cyst or a luteal structure at PGF2α administration or at insemination were not associated with P/AI. The new and re-used CIDR inserts produced comparable concentrations of serum progesterone 3 h, 3 days and 7 days post CIDR insertion. In conclusion, the RG-Ovsynch improved the P/AI whereas the New-CIDR and the G-New CIDR regimens tended to increase the P/AI compared with Ovsynch. Marginal differences in P/AI between RG-Ovsynch, New-CIDR, and G-New-CIDR together with prolonged diagnosis-to-FTAI in RG-Ovsynch should be considered if to evaluate the economic value of these regimens.

Treatment of cows that fail to respond to pre-synchronization treatments with a CIDR-Ovsynch regimen improves the overall pregnancy percentage after a double Ovsynch treatment regimen

In this study, there was evaluation of pregnancy per AI (P/AI) as a result of the first postpartum AI following four ovulation-synchronization treatments. Treatment regimens were Ovsynch-56 (OVS, n = 875; GnRH1-7d-PGF2α-56h-GnRH2-16h-FTAI), CIDR-OVS (n = 1001; OVS plus CIDR inserts between GnRH1 and PGF2α), Double-Ovsynch (DOVS, n = 663; imposing Pre-OVS followed by breeding-OVS 7 days later), and Modified-DOVS (M-DOVS, n = 1397; imposing Pre-OVS followed either by breeding-OVS or CIDR-OVS based upon the ovarian structure at GnRH1). Cows with a corpus luteum were assigned to a breeding-OVS treatment regimen and those that did not have a corpus luteum were assigned to the CIDR-OVS treatment regimen. Compared with OVS, the P/AI of the cows in the M-DOVS (OR = 1.5, P = 0.001) and CIDR-OVS (OR = 1.4, P = 0.017) was greater at day 30. At day 70, only in the M-DOVS group was there a greater P/AI compared with the OVS group (OR = 1.7, P < 0.001). Pregnancy loss between days 30 and 70 was greater in cows of the CIDR-OVS (OR = 1.9, P = 0.014) compared with those of the OVS group. In cows of the M-DOVS, the dominant ovarian structures (follicle, corpus luteum or cyst) at different time-points of the pre-synchronization period and occurrence of estrus at the end of this period were not associated with P/AI at day 30 post-AI. In conclusion, imposing CIDR-OVS in cows that did not respond to pre-synchronization treatments, resulted in an enhanced pregnancy percentage with the use of the DOVS.

The effect of pre-breeding vitamin E and selenium injection on reproductive performance, antioxidant status, and progesterone concentration in estrus-synchronized Mehraban ewes.

The present study was conducted to assess the effects of pre-breeding vitamin E and selenium (ESe) injections on the reproductive performance, antioxidant status, and serum progesterone (P4) concentration in estrus-synchronized Mehraban ewes. During the breeding season, 38 ewes (3-4years) were divided into two groups (n = 18), and the synchronization of estrus was achieved by intravaginal insertion of 0.3g progesterone CIDR device for 13days followed by 350IU eCG at CIDR withdrawal. Ewes were kept under pasture conditions and exposed to Mehraban rams 48h following CIDR withdrawal. The experimental treatments were control and ESe injection. The ESe group was received three intramuscular (5mL) injections of Ese (0.5mg/mL of selenium as sodium selenite and 50IU vitamin E as DL-α- tocopheryl) once every 2weeks. Specifically, Ese was administered at 2weeks before CIDR insertion, at the times of CIDR insertion and CIDR withdrawal. Fertility, prolificacy, lambing rate, and birth weight were recorded after parturition. Blood samples were collected at CIDR insertion, CIDR withdrawal, 5, 10, and 15days after ram exposure. Fertility, prolificacy, lambing rate, and birth weight did not improve by Ese treatment, but viabilityof lambs was higher in ESe than control (P < 0.05). Serum total antioxidant capacity at day 5 and P4 at day 10 after ram exposure was higher in ESe than control (P < 0.05). In conclusion, sheep breeders can use ESe at CIDR insertion and withdrawal times to potentiate antioxidant status and progesterone profile of estrus-synchronized Mehraban ewes.

Dynamics of Selected Trace Minerals during Estrus Induction in Anestrus Sahiwal Cattle

The present study evaluated the effect of circulatory trace mineral profiles on fertility response during estrus induction by progesterone based therapy in acyclic Sahiwal cattle. Sahiwal cows and post-pubertal heifers (n=25 each) with true anestrus condition (acyclicity confirmed ultrasonographically) were subjected to CIDR-based protocol (intravaginal CIDR application for 7 days, 500 IU eCG at CIDR removal, followed by estrus observation and AI). In heifers, additionally an injection of 5.0 mg estradiol valerate at CIDR insertion was given. Blood samples on days 0 (before CIDR application), 3, 5, 7 and 9 were collected. Almost similar estrus induction (68% vs. 64%) and subsequent conception rates (41.2% vs. 50%) during the first induced estrus were recorded in cows and heifers, respectively. During the course of treatment, significant (P 0.05) was recorded for iron concentration vis-a-vis estrus induction response. Hence, it is indicated that circulatory copper, zinc and manganese profiles influence the reproductives energy in acyclic animals and their suboptimal profiles may reduce the efficacy of estrus induction protocols in Sahiwal cattle.

299 Treatment with prostaglandin F2α and an intravaginal progesterone insert in advance of gonadotropin-releasing hormone enhances response to estrus synchronization in mature beef cows

Abstract An experiment was designed to evaluate the effect of treatments in advance of gonadotropin-releasing hormone (GnRH; 100μg gonadorelin) administered at the start of estrus synchronization. We hypothesized that administration of prostaglandin F2α (PG; 500μg cloprostenol) followed by treatment with an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) would result in increased follicle size at GnRH, thereby enhancing response to GnRH and overall response to estrus synchronization. Postpartum suckled beef cows (n = 183) in two locations were assigned to one of five treatments based on age, days postpartum, and body condition score. Treatments (Figure 1) were designed as a two-by-two factorial with a control (Treatment 1). Treatments 2–5 received a CIDR insert from Day -17 to Day -10, with (Treatments 2 and 3) or without (Treatments 4 and 5) administration of PG coincident with CIDR insertion on Day -17. Coincident with GnRH administration on Day -10, CIDR inserts were either removed (Treatments 2 and 4) or remained in place until Day -3 (Treatments 3 and 5). On Day -3, estrus detection aids were applied and a representative subset of cows in each treatment were fitted with estrus detection transmitters. Blood samples were collected on Days -27, -17, -10, -3, and 0 for determination of serum estradiol and/or progesterone concentrations via radioimmunoassay. For a representative subset of cows (n = 111), transrectal ovarian ultrasound was performed to assess ovarian follicle size and presence of corpora lutea on Days -17, -10, -3, and 0. Treatment with PG and CIDR in advance of GnRH resulted in improvements (P &amp;lt; 0.05) in several response variables, including follicle size on Day -17 and estrous response prior to AI. Results support the hypothesis that administration of PG and treatment with a CIDR for 7 d prior to GnRH improves likelihood of GnRH response and enhances response of mature cows to estrus synchronization.

PSVIII-42 Effect of presynchronization using prostaglandin F2α prior to a shortened progesterone exposure in fixed-timed AI of crossbred beef cows nursing calves

Abstract Presynchronization has been shown to improve AI pregnancy rates in dairy cattle, by improving the effectiveness of the initial GnRH treatment required for follicular control in estrous synchronization protocols. An experiment was designed to evaluate the effect of prostaglandin presynchronization in a fixed-timed AI (FTAI) protocol with a shortened progesterone exposure in beef cows. A total of 135 fall calving (September-November) crossbred beef cows from two locations were randomized to receive either: A) prostaglandin (25mg; Lutalyse, Zoetis, Kalamazoo, MI) administered two days prior to synchronization with GnRH (100mg; Factrel, Zoetis) and progesterone (1.38g P4; CIDR, Zoetis) for 6 days, or B) Control, the same synchronization protocol without Lutalyse pretreatment. On day 6 (Day 0: CIDR insertion) CIDR was removed and 25mg of prostaglandin was administered and 72 hours later fixed-timed AI with concurrent injection of 100mg of GnRH. Conventional frozen semen from Simmental-Angus sires was used for AI and fertile Angus bulls were used for pasture exposure. Pregnancy was determined by ultrasound 30 days after AI and again 30 days after clean-up bull exposure for 30 days. Statistical analysis was performed using the frequency procedure of SAS (Cary, NC) and significance was set at X2 &amp;lt; 0.05. Pregnancy rate to timed AI was 71.4% for Treatment A compared to 80.3% for Treatment B (Control). Although these results were greater than previously reported at these research stations, there was no statistical difference (X2=0.23) between treatments. Overall pregnancy rates tended to be different (X2=0.06) and were potentially influenced by treatment or shortened exposure to progesterone in synchronization. Research supported by University of Arkansas Division of Agriculture.