Single PGF2α Research Articles

Ovarian Dynamics and Changes in Estradiol-17β and Progesterone Relationship with Standing Estrus, Preovulatory Follicles, and Ovulation Using Single Prostaglandin F2α Injection in Barbari Goats.

The purpose of the present research was to define ovarian follicular dynamics and plasma endocrine profiles in response to a single PGF2α injection, administered indiscriminately during the breeding season of Barbari goats. Ovarian dynamics were observed at every 12 h interval by using B mode ultrasonography, blood samples for hormonal analysis such as estradiol 17β and progesterone were collected at every 12 h interval, and bucks with aprons were used to identify standing estrus at every 6 h interval. Relative to PGF2α, the start of standing estrus and ovulation differ (p < 0.05) between early- (n = 7), intermediate- (n = 6), and late-responding (n = 6) goats. The highest plasma level of estradiol 17β was detected 12 h prior to ovulation. The average diameter of the ovulatory follicle and length of standing estrus were comparable (p > 0.05) between the goats. The corpus luteum degenerated more quickly (p < 0.05) in early- than intermediate- and late-responding goats. Dominant follicle diameter and estradiol 17β concentration also differ (p < 0.05) among groups. Although the plasma level of progesterone did not vary (p = 0.065), the variation in progesterone concentration with time differed (p < 0.05) amongst the goats. As a result, this research indirectly reveals that the beginning of standing estrus, end of estrus, and ovulation after PGF2α might fluctuate in Barbari goats because of follicular and hormonal dynamics during the luteal phase.

Evaluation of luteolysis, follicle size, and time to ovulation in Holstein heifers treated with two different analogs and doses of prostaglandin-F2α

Objectives were to evaluate the effect of 2 analogs of PGF2α (cloprostenol vs. dinoprost) and 2 doses (1 injection vs. 2 injections) on luteolysis, follicle diameter, hormonal concentrations, and time to ovulation in dairy heifers. Holstein heifers were fitted with automated estrus detection devices and had their estrous cycle synchronized using PGF2α and an intravaginal insert containing progesterone. Heifers detected in estrus were blocked by weight and randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement: cloprostenol on d 7 after estrus (CLOx1; n = 45), cloprostenol on d 7 and 8 after estrus (CLOx2; n = 41), dinoprost on d 7 after estrus (DINx1; n = 43), or dinoprost on d 7 and 8 after estrus (DINx2; n = 44). Treatment with the first injection of PGF2α was defined as experiment d 0. Area and blood flow of corpus luteum (CL) and diameter of follicles >5 mm were recorded every 12 h from d 0 to estrus and every 6 h thereafter until ovulation. Blood was sampled every 6 h from d 0 until ovulation. Heifers treated with cloprostenol had shorter interval to luteolysis (± SEM; CLOx1 = 23.5 ± 2.2, CLOx2 = 22.9 ± 2.2, DINx1 = 32.6 ± 2.7, DINx2 = 26.4 ± 2.1 h); however, time to ovulation was not affected by treatment. A smaller proportion of heifers treated with a single injection of PGF2α underwent luteolysis compared with heifers treated with 2 injections (CLOx1 = 84.6 ± 6.2, CLOx2 = 100.0 ± 0.0, DINx1 = 59.7 ± 9.8, DINx2 = 96.3 ± 2.7%). Proportion of heifers that ovulated was smaller for DINx1 compared with other treatments (CLOx1 = 88.8 ± 5.1, CLOx2 = 100.0 ± 0.0, DINx1 = 55.2 ± 9.7, DINx2 = 94.4 ± 3.4%). Ovulatory follicle diameter was larger for DINx1 (18.2 ± 2.7 mm) compared with DINx2 (17.4 ± 2.7 mm), whereas dose did not affect the diameter of the ovulatory follicle in heifers treated with cloprostenol (CLOx1 = 17.6 ± 2.7 vs. CLOx2 = 17.8 ± 2.8 mm). Among heifers that underwent luteolysis, progesterone concentrations from 18 to 36 h after treatment were lesser in heifers treated with cloprostenol compared with those treated with dinoprost. Type of PGF2α did not affect progesterone concentrations past 36 h from treatment; however, heifers treated with 2 PGF2α injections had lesser progesterone concentrations and CL blood flow from 36 to 72 h after treatment compared with heifers that received a single PGF2α injection.

Comparative Study on Effect of Different Estrus Synchronization Protocols on the Pattern of Estrus, Conception Rate and Serum Hormonal Profile in Indigenous Kangayam Cows

Background: The indiscriminate crossbreeding is the major cause for losses as well as for risk to existing breeds. Kangayam, a pride indigenous cattle breed of Tamil Nadu, also badly affected due to this unplanned indiscriminate breeding. Urgent and immediate action is required to protect this traditional breed. Estrus synchronization would be a best tool to improve the fertility rate and increase the population of this breed under field condition. Methods: Fifty Kangayam cows selected at farmer’s field were divided into Group I, II, III, IV (Treatment groups) and Group V (Control group). Estrus synchronization with single PGF2α, double PGF2α, CIDR+PGF2α and ovsynch protocols were used in Group I, II, III and IV cows, respectively and inseminated during induced estrus. Group V cows were inseminated during observed estrus. The pattern of estrus, fertility rate and serum hormonal profiles on different days of treatment were studied. Result: The conception rates were higher in double PGF2α (80 per cent) and ovsynch protocol (80%) followed by CIDR+ PGF2α (70%). The progesterone (ng/ml) concentration was significantly (P≤0.05) higher during estrus induction with PGF2α in treatment groups than during selection and insemination. The serum estradiol-17β concentration was significantly (P≤0.05) higher during insemination (24.21±1.74 to 25.57±0.80 pg/ml) than during PGF2α injection (12.81±0.25 to 13.68±0.30 pg/ml). The study concluded that higher conception rate in indigenous Kangayam cows can be obtained with synchronization using Double PGF2α and Ovsynch protocol followed by CIDR+PGF2α protocol.

Economic impact of adding a second prostaglandin F2α treatment during an Ovsynch protocol using a meta-analytical assessment and a stochastic simulation model

Incomplete luteal regression after treatment with a single dose of PGF2α during an Ovsynch protocol decreases fertility to timed artificial insemination (AI). An additional treatment with PGF2α 24 h after the first dose has been recommended to increase the proportion of cows with complete luteal regression and subsequent pregnancy per AI (P/AI). This is, however, associated with additional costs of labor and product. The objective was to develop a stochastic partial budget model to estimate the economic impact of an additional PGF2α treatment on d 8 during an Ovsynch protocol in primiparous and multiparous cows. A systematic review of the literature and a meta-analytical assessment was performed to evaluate the effects of adding a second PGF2α treatment during the Ovsynch protocol on P/AI in lactating dairy cows. Thirteen randomized controlled experiments from 11 published manuscripts including 9,735 cows were used. We were able to retrieve information regarding parity from 9 experiments from 7 manuscripts (2,367 primiparous cows and 5,356 multiparous cows). An additional dose of PGF2α yielded a 5.60 risk difference in P/AI [95% confidence interval (CI) = 3.69-7.52]. In primiparous cows and multiparous cows, an additional dose of PGF2α yielded a 4.24 (95% CI = 0.31-8.17) and a 5.31 risk difference in P/AI (95% CI = 2.75-7.87). Revenue was based on the associated improvement in reproductive performance because of an increase in P/AI multiplied by the value of a pregnancy (PGVAL). Median PGVAL was €252, ranging from €42 (fifth percentile) to €623 (95th percentile). Based on parity, median PGVAL was €205 (5th percentile = €43; 95th percentile = €651) and €264 (5th percentile = €88; 95th percentile = €598) for primiparous (n = 1,252) and multiparous cows (n = 3,003), respectively. Using a stochastic simulation model with 10,000 iterations, adding a second PGF2α dose on d 8 was more profitable (€7.76/cow; 5th percentile = €0.01; 95th percentile = €29.40) compared with a single PGF2α administration on d 7. In primiparous cows, adding a second PGF2α treatment was more profitable (€1.99/cow; 5th percentile = -€3.08; 95th percentile = €22.52) in 67% of all simulated iterations. In multiparous cows, adding a second PGF2α treatment was more profitable (€7.92/cow; 5th percentile = -€0.09; 95th percentile = €28.22) in 95% of all simulated iterations. In conclusion, there was a clear benefit of an additional PGF2α treatment during the Ovsynch protocol on P/AI (+5.6 percentage units). Despite additional costs for hormones and labor, an additional treatment with PGF2α on d 8 was more profitable in 95% of all scenarios because of the associated increase in fertility. It turned out, however, that adding a second PGF2α treatment was more profitable in multiparous cows compared with primiparous cows.

Response to Therapeutic Abortion in Lactating Dairy Cows Carrying Dead Twins during the Late Embryo/Early Fetal Period.

Simple SummaryThe presence of dead embryos/fetuses can be precisely detected around 60 days post-insemination in dairy cattle. Little information on the fate of dead twins has been published. Practitioners usually apply a therapeutic abortion using prostaglandin F2α (PGF2α) or its analogs to reduce the associated extended interval to estrus. This study evaluated the dose–response effect of PGF2α inducing abortion in cows with two dead twins at pregnancy diagnosis 28–34 days post-AI (late embryonic period) or at confirmation of pregnancy 49–55 days post-AI (early fetal period). An increased PGF2α dose had no influence on the induction of abortion and the induced abortion rate was inversely associated with milk production during the late embryonic period, whereas an increased PGF2α dose was found to offer improvements during the early fetal period.This study examined the dose–response effect of prostaglandin F2α (PGF2α) when used to induce abortion in cows with two dead twins at pregnancy diagnosis 28–34 days post-AI (late embryonic period: LE) or at pregnancy confirmation 49–55 days post-AI (early fetal period: EF). The study population consisted of 415 cows receiving a single PGF2α dose (PG1 group: 254 LE and 161 EF cows) and 200 receiving a 1.5 × PGF2α dose (PG1.5 group: 121 LE and 79 EF cows). The induced abortion rate was significantly lower (chi-square test; p < 0.0001) in the EF (34.6%) than LE cows (88%), and was also reduced (p = 0.001) in the EF PG1 group (28%) compared with the EF PG1.5 group (48.1%). High milk production (≥45 kg) was the only factor influencing the induced abortion rate in LE cows (odds ratio 0.2; p < 0.0001), whereas the odds ratio for induced abortion of PG1.5 cows was 2.3 (p = 0.005) in EF cows. In conclusion, an increased PGF2α dose had no effect on abortion induction during the late embryonic period and its rate was inversely associated with milk production. This higher PGF2α dose did, however, offer benefits during the early fetal period.

Comparison of efficacy of Ovsynch protocol to single PGF2α administration in treatment of individual dairy cows with post-service subestrus.

The aim of this study was to evaluate the efficacy of the Ovsynch protocol in the treatment of post-service subestrus in individual dairy cows compared to a single administration of PGF2α. The study was performed on 517 Polish Friesian Holstein cows with post-service anestrus over four years in 3 dairy herds under a herd health program. Cows (n=240) diagnosed ultrasonographically as non-pregnant and with a mature corpus were treated with a single PGF2α administration and inseminated at detected estrus. Cows without corpus (n=277) were treated with the Ovsynch protocol. The estrus detection rate after PGF2α administration, percentages of cows pregnant after the treatment and at day 260, intervals from parturition to treatment and from treatment to conception and pregnancy loss rates were calculated. The overall percentage of cows pregnant after treatment did not differ between animals treated with the Ovsynch protocol and with PGF2α (38.9% vs. 42.5%; p>0.05). In herd A the percentage of cows pregnant after treatment was significantly lower (p⟨0.05) for the Ovsynch group than for the PGF2α group (30.2% vs. 61.2%). In contrast, in herd C the percentage of cows pregnant after treatment was significantly higher (p⟨0.05) in the Ovsych group than in the PGF2α group (39.6% vs. 28.8%). The overall estrus detection rate after administration of PGF2α was 59.6%. However, it was significantly lower (p⟨0.05) in herd C (44.7%) than in herds A (79.6%) and B (76.3%). The overall pregnancy loss rate ranged from 5.1% to 13.3% and did not differ significantly between herds and treatment groups (p>0.05). In conclusion, Ovsynch protocol can be a useful alternative for treatment of post-service suboestrus in individual cows in dairy herds with insufficient oestrus detection.

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

Simple SummaryIn 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.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 PGF2α 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.

Presence of multiple corpora lutea affects the luteolytic response to prostaglandin F2α in lactating dairy cows.

Since the 1970s, luteolytic doses used for synchronizing estrus in dairy cattle have remained unchanged. This study aimed to evaluate the dose-response effect of prostaglandin F2α (PGF2α), which is used for synchronizing estrus, and subsequent fertility in cows with two or more corpora lutea (CL). The study population consisted of 1,683 cows with a single CL (1CL), 501 cows with multiple CL receiving a single dose of PGF2α (2CL1), and 252 cows with multiple CL receiving a 1.5 × PGF2α dose (2CL1.5). Cows with a single CL (n = 1,245) showed estrus significantly (P < 0.01) earlier (3.01 ± 1.23 days; mean ± SD) than cows with multiple CL (n = 287; 3.33 ± 1.69 days). Using 1CL cows as reference, the odds ratio (OR) for the estrus response in 2CL1 cows was 0.13 (P < 0.0001), whereas the ORs for estrus response and pregnancy of 2CL1.5 cows were 1.8 (P = 0.0001) and 1.7 (P = 0.001), respectively. Based on the results for only the 2CL1 cows, the OR for the estrus response was 0.7 (P = 0.01) for cows producing ≥ 45 kg of milk at treatment, compared to the remaining cows producing < 45 kg of milk. Our results showed that the presence of multiple CL reduced the estrus response to that induced by a single PGF2α dose and milk production was inversely associated with this response, whereas an increased PGF2α dose improved the estrus response. Therefore, an increase in the standard PGF2α dose is recommended.

Postpartum prostaglandin F2α administration affects colostrum yield, immunoglobulin G, and piglet performance.

ObjectiveCurrent study was conducted to determine the effect of postpartum prostaglandin F2α (PGF2α) administration on colostrum and milk yield, colostrum immunoglobulin G (IgG) and piglet growth performance.MethodsIn total, 36 sows were included in the experiment. The sows were classified into two groups: i) control (n = 11) and ii) PGF2α (n = 25). Sows in the PGF2α group received 10 mg of PGF2α within an hour after farrowing. The body weight of piglets was measured at 0 and 24 h after birth to estimate colostrum consumption. Colostrum was collected at 1 and 24 h after farrowing to determine IgG concentrations. For milk yield study, the remaining sows in the PGF2α group (n = 23) were divided into two subgroups: i) single PGF2α (n = 12) and ii) multiple PGF2α (n = 11). In the multiple PGF2α, the sows received repeated doses of PGF2α at seven and 14 days postpartum. The piglets’ body weight was measured at 0, 1, 5, and 20 days of age. The milk yield of the sows was calculated.ResultsColostrum yield of sows averaged 5.62±2.25 kg. Sows treated with PGF2α postpartum had a higher colostrum yield than control (7.01 and 5.12 kg, p<0.05). The concentration of IgG in colostrum at 24 h in the PGF2α group was higher than the control (31.6 and 17.4 g/L, p<0.05). For primiparous sows, milk yield was highest in the sows treated with multiple doses of PGF2α during lactation and lowest in control sows (10.25 and 7.61 kg, p<0.05). Colostrum intake was higher in the treatment than the control groups (+56.7 g, p<0.05). Primiparous sows treated with multiple doses of PGF2α had a higher litter weight than controls (p<0.01).ConclusionPostpartum treatment with PGF2α improved colostrum yield and IgG in multiparous sows and increased colostrum intake of piglets. Multiple administration of PGF2α improved the milk yield and increased litter weight of piglets in primiparous sows.

Conception Rate of 11 Months Old Dairy Heifer Following Artificial Insemination with Natural Estrus and PGF2α Treatment

The aim of this study was to evaluate the conception rate of 11-months old dairy heifer following artificial insemination with natural estrus or treated with PGF2α at PT. Ultra Peternakan Bandung Selatan. A case study was applied in this study involving all data of 700 records for date of birth, body weight and reproduction status. Sample was selected according the complete records with criteria of age was 11±3 months, body weight >300kg, having normal reproduction organs detected by rectal palpation. The results showed that from observation of selected 300 samples out of 700 heifers, 25 heifers of them were natural estrus (Control), 50 estrus after single PGF2α injection (PG), 95 following single PGF2α and left to normal estrus after 21 days (PG-N), 50 after double PGF2α (2PG), and the rest of 80 heifers showed estrus following double PGF2α – Natural estrus (2PG-N) with the conception rate (CR) of 17/25(68%), 44/50(88%), 42/50(84%), for the respective groups. None of heifers in PG-N and 2PG-N groups became pregnant after first insemination. The body weight (BW) was classified into Low (336-347kg), Medium (348-359kg) and High (360-372kg). The total conception rate was 34%. The CR for Low, Medium and High BW were 41%, 32% and 31%, respectively. The conclusion, the 11-months old heifer was possible to become normal pregnant following insemination without and with PGF2α injection when reached body weight over 300 kg. To ensure the higher number animal exhibiting estrus, double PGF2α injections should be applied.

Short communication: Reproduction outcomes in dairy heifers following a 14-d progesterone insert presynchronization protocol

The objectives were to evaluate pregnancy per artificial insemination (AI), days to first AI, and proportion pregnant within 7 d of AI eligibility in dairy heifers subjected to presynchronization compared with dairy heifers not presynchronized. Thirty days before AI eligibility, Holstein heifers were assigned randomly to 1 of 3 groups: 14-d controlled internal drug release (CIDR; containing progesterone) presynchronization, PGF2α presynchronization, or control (no presynchronization). Heifers in the 14-d CIDR presynchronization treatment (n = 119) received a CIDR on d -30, which was removed on d -16, followed by an injection of PGF2α upon entry to the breeding program (d 0). Heifers in the PGF2α presynchronization treatment (n = 118) received an injection of PGF2α on d -11 and d 0. Control heifers (n = 121) were not presynchronized and received an injection of PGF2α on d 0. All heifers received tail paint on d 0 to facilitate once-daily detection of estrus (based on paint removal). Heifers detected in estrus received AI with conventional semen on the same morning as detected estrus. Generalized linear mixed models were used to assess mean treatment differences. Following PGF2α treatment on d 0, more heifers were detected in estrus in the first 7 d after eligibility in the 14-d CIDR group (95.8%) compared with the PGF2α (74.6%) and control (66.9%) groups. Days to first AI differed between treatments (14-d CIDR = 3.6 d vs. PGF2α = 5.0 d vs. control = 6.8 d). Pregnancy per AI for first AI within 7 d of eligibility was 71.9% (14-d CIDR), 58.0% (PGF2α), and 61.7% (control), and differed between 14-d CIDR and PGF2α heifers. Presynchronization with a 14-d CIDR increased the proportion of heifers pregnant in the first 7 d of eligibility (14-d CIDR = 68.9% vs. PGF2α = 43.2% vs. control = 41.3%). Projected days on feed (d 0 to projected calving date) were 295 (14-d CIDR), 302 (PGF2α), and 305 (control), and were different between the 14-d CIDR and control heifers. The potential economic benefit to the producer was $15.85 per heifer presynchronized with a 14-d CIDR protocol compared with the control group. Treatment of dairy heifers with a 14-d CIDR effectively presynchronized estrus, resulting in a greater proportion detected in estrus, reduced days to first AI, and an increased proportion of heifers pregnant within the first 7 d after breeding eligibility compared with heifers presynchronized with a single PGF2α injection and control heifers.

Effect of Utilization of Single or Double Prostaglandin Administration Within an Ovsynch Fixed-Time Artificial Insemination Protocol During Summer Season in Dairy Cows

Abstract This study investigated the fertility of dairy cows during summer season after treatment with a single or double PGF2α in a progesterone (P4)-based Ovsynch protocol for fixed-time artificial insemination (FTAI). The data were compared to a treatment effectuated during winter season. Two groups of 60 dairy cows each were randomly assigned on day 60 post-partum to single PGF2α or double PGF2α group. At removal of the P4 treatment the single PGF2α group received a single dose and the double PGF2α group received two doses of PGF2α at 24 hours apart. In each group, 30 cows were treated during the summer (June, July and August) and 30 cows during the winter (December, January and February) season. During summer season a double PGF2α dose did not influence pregnancy rate at FTAI but improved cumulative pregnancy rate 60 days after FTAI (43% vs 69% for single PGF2α and double PGF2α administration, respectively; P&lt;0.05). During winter season the single or double PGF2α administration did not modify PR or cumulative PR. In conclusion, during summer the utilization of a double instead of single PGF2α treatment into a P4-based Ovsynch-FTAI protocol did not increase pregnancy rate at FTAI but improved cumulative pregnancy rate.

Follicular dynamics and changes in oestradiol-17β, progesterone and LH profiles following PGF2α induced oestrus in early and late ovulating Beetal goats.

This study compares the factors associated with variable interval to oestrus and ovulation between early versus late ovulating goats following PGF2α administration. The time of ovulation in Beetal goats (n=38) was monitored through transrectal ultrasound at every 6hr following a single dose of PGF2α (experiment 1). Variations in oestrus and ovulation times were further explored throughthe changes in follicular dynamics, endocrine profiles and behaviour in another set of goats (n=13) following single PGF2α given randomly during the lutealphase (experiment 2). The ovulation time varied between 60 and 96hr, and 57% of ovulations occurred by 72hr following PGF2α (experiment 1). Accordingly, the goats (n=13) in the second experiment were retrospectively dividedeither into early and/or late ovulating, that is, ≤72 and/or ≥84hr following PGF2α . The onset of oestrus, peak estradiol-17β concentration and LH surge after PGF2α was first observed in early than late ovulating goats (p<0.05). The goats ovulating early had larger follicleand smaller CL in diameter at the time of PGF2α administration than those ovulating late (5.4±0.2 vs. 4.3±0.2mm and 10±0.6 vs. 11.8±0.3mm, respectively; p<0.05). Likewise, plasma progesteroneconcentration tended to be lower (p=0.087) in earlythan late ovulating goats. In conclusion, the size of dominant follicle and CL at the time of PGF2a determines the interval toovulation following a single dose of PGF2a during the luteal phase.

Evaluation of two estrus synchronization protocols in dairy cattle at North Shoa zone Ethiopia

This study was initiated to change the hesitation of the farmer on the effectiveness of estrus synchronization under their (Ethiopian small holder) livestock management system using two synchronization protocols. Non-pregnant animals with normal reproductive tract and that fulfilled the preconditions for estrus synchronization were considered for treatment &amp; assigned into two synchronization protocols (single PGF2α injection; and double PGF2α injection). Among 94 (27 heifer and 67 cows) synchronized cows using one and two injections of PGF2α protocols 26 heifers and 63 cows (89/94.7%) were exhibited estrus by visual observation and rectal palpation the remaining 5 (5.3%) did not illustrate heat. The overall pregnancy was 59.6 % with overall birth 94.3 %. High pregnancy was obtained in the double injection of PGF2α treatment group (63.1 %) than animals treated with one shot protocol 55.8 % there were statistically significant difference between treatments (p&lt;0.05). Higher pregnancy was obtained from cross breed animals than local breeds. More over most of the animals come to estrus greater than 96 hrs. There was also significant difference between technicians on detecting the CL and conception. The estrus response, conception rate, pregnancy rate and calving rate was higher in both protocols so producers or farmers can use either the two protocols to achieve remarkable result but tight follow-ups and more resources are need to be exploited at farmer level.

Effect of two low doses of prostaglandin F2α on luteolysis in dairy cows

In this preliminary study, we determined the effect of a modified method involving the administration of two low doses of prostaglandin F2α (PGF2α) at an interval of 24 h on luteolysis in dairy cows, and compared it with the standard single-dose method. Twenty-six cows were assigned to three groups treated with two low doses (TLD group, n = 10), one standard dose (SD group, n = 10), and one low dose (OLD group, n = 6) on day 9 to 10 of the oestrous cycle (day 0 = the day of PGF2α administration). Their serum progesterone (P4) levels and corpus luteum (CL) sizes were measured daily from day 0 to 4 to assess CL regression. The results indicated that the proportion of complete luteolysis, indicating a P4 value ≤ 1 ng/mL on day 3, was higher in the TLD group (100.0%) than in the SD (60.0%) and OLD (66.7%) groups. Ultrasonically detected changes in the CL area correlated with the shifts in the P4 values in both the TLD and the SD groups. The remaining CL area was significantly smaller in the TLD group (17.8% ± 3.3%) than in the SD or OLD group on day 4. Thus, we concluded that the proportion of luteolysis in cows was increased with two low doses of PGF2α as compared to a single PGF2α dose, indicating the necessity of the second dose of PGF2α. However, further studies with larger sample sizes in the field are required.

Short communication: Optimization of a timed artificial insemination program for reproductive management of heifers in Canadian dairy herds

Pregnancy per AI (P/AI) following the use of 1 of 2 timed AI (TAI) protocols and 2 different intervals between TAI and resynchronization were compared in heifers that were inseminated with either conventional or sex-sorted semen. Holstein heifers (n = 317; 527 inseminations) were submitted to a 5-d Cosynch protocol with (+) or without (-) GnRH at the time of controlled internal drug release (CIDR) insertion on d 0, CIDR removal and a single PGF2α treatment on d 5, and TAI plus GnRH on d 8 (72 h later). Visual estrus detection (ED) was conducted on d 6 in the afternoon and d 7 in the morning and heifers observed in estrus were artificially inseminated on d 7 in the afternoon. Heifers were alternately assigned conventional or sex-sorted semen. Pregnancy was diagnosed by ultrasound 27 and 42 d after AI, and heifers diagnosed as nonpregnant were resynchronized, up to 3 times, starting on d 27 or 34 to provide an interbreeding interval of 35 or 42 d. Overall, TAI protocol had no effect on P/AI at 27 or 42 d after artificial insemination or on pregnancy loss, but P/AI following the first service tended to be higher in the -GnRH TAI group (66.3 vs. 56.8%). Pregnancy per AI at 27 d (61.9 vs. 55.5%) tended to differ between conventional and sex-sorted semen. Heifers artificially inseminated based on ED tended to have a greater P/AI (67.6 vs. 58.2%) and had decreased pregnancy loss (0.0 vs. 4.1%) than those submitted to TAI. A greater number of heifers in the -GnRH TAI protocol were artificially inseminated on ED than the +GnRH TAI protocol (21.5 vs. 13.7%). No difference in P/AI was observed between the 35- and 42-d interbreeding intervals; however, more heifers in the 42-d group were artificially inseminated based on ED than in the 35-d group (22.7 vs. 7.8%). A 5-d Cosynch+CIDR TAI protocol without the initial GnRH and with a single PGF2α at CIDR removal is an acceptable alternative to achieve high P/AI when either conventional or sex-sorted semen is used in Holstein heifers. Breeding heifers based on detected estrus increases labor, but has the potential to increase fertility.

Adding a second prostaglandin F2α treatment to but not reducing the duration of a PRID-Synch protocol increases fertility after resynchronization of ovulation in lactating Holstein cows

Our objective was to evaluate the effect of a second PGF2α treatment and duration of an Ovsynch protocol that included a progesterone-releasing intravaginal device (PRID) on progesterone (P4) concentrations and pregnancies per artificial insemination (P/AI) after resynchronization of ovulation and timed artificial insemination (TAI). Lactating Holstein cows (n=821) were assigned randomly at a nonpregnancy diagnosis (d 0) to 3 resynchronization protocols: (1) GnRH, d 0; PGF2α, d 7; GnRH, d 9.5 (7D1PGF); (2) GnRH, d 0; PGF2α, d 7; PGF2α, d 8; GnRH, d 9.5); (7D2PGF); or (3) GnRH, d 2; PGF2α, d 7; PGF2α, d 8; GnRH, d 9.5 (5D2PGF). All cows received a PRID at the first GnRH treatment of the resynchronization protocol, which was removed at the first PGF2α treatment, and all cows received TAI approximately 16h after the second GnRH treatment. Blood samples were collected from a subgroup of cows at each treatment of the resynchronization protocols. At 32 d after TAI, cows receiving a second PGF2α treatment (7D2PGF + 5D2PGF cows) had more P/AI (42.6 vs. 35.7%) than cows receiving a single PGF2α treatment (7D1PGF cows). For cows treated with a second PGF2α treatment, decreasing the duration of the protocol did not increase P/AI (41.4 vs. 43.8% for 7D2PGF vs. 5D2PGF cows). At 60 d after TAI, P/AI did not differ between cows treated with the 1 PGF2α (7D1PGF cows) or 2 PGF2α (7D2PGF + 5D1PGF cows) treatments (32.5 vs. 37.9%, respectively). In addition, reducing the duration of the protocol did not increase P/AI at 60 d after TAI (37.8 vs. 38.5% for 7D2PGF vs. 5D2PGF cows). Pregnancy loss from 32 to 60 d after TAI was not affected by the number of PGF2α treatments (8.5 vs. 10.6%, for 7D1PGF vs. 7D2PGF + 5D2PGF cows) or the duration of the protocol (9.1 vs. 12.1%, for 7D2PGF vs. 5D2PGF cows). The percentage of cows with incomplete luteal regression at the second GnRH treatment tended to differ among treatments and was lowest for 7D2PGF cows, intermediate for 5D2PGF cows, and greatest for 7D1PGF cows (1.9 vs. 6.9 vs. 11.0%, respectively). In conclusion, addition of a second PGF2α treatment tended to decrease the percentage of cows with incomplete luteal regression and increased P/AI 32 d after AI, whereas decreasing the duration of the Ovsynch protocol did not increase P/AI.

Comparison of the pregnancy rates and costs per calf born after fixed-time artificial insemination or artificial insemination after estrus detection in Bos indicus heifers

This study compared pregnancy rates (PRs) and costs per calf born after fixed-time artificial insemination (FTAI) or AI after estrus detection (i.e., estrus detection and AI, EDAI), before and after a single PGF2α treatment in Bos indicus (Brahman-cross) heifers. On Day 0, the body weight, body condition score, and presence of a CL (46% of heifers) were determined. The heifers were then alternately allocated to one of two FTAI groups (FTAI-1, n = 139) and (FTAI-2, n = 141) and an EDAI group (n = 273). Heifers in the FTAI groups received an intravaginal progesterone-releasing device (IPRD; 0.78 g of progesterone) and 1 mg of estradiol benzoate intramuscularly (im) on Day 0. Eight days later, the IPRD was removed and heifers received 500 μg of PGF2α and 300 IU of eCG im; 24 hours later, they received 1 mg estradiol benzoate im and were submitted to FTAI 30 to 34 hours later (54 and 58 hours after IPRD removal). Heifers in the FTAI-2 group started treatment 8 days after those in the FTAI-1 group. Heifers in the EDAI group were inseminated approximately 12 hours after the detection of estrus between Days 4 and 9 at which time the heifers that had not been detected in estrus received 500 μg of PGF2α im and EDAI continued until Day 13. Heifers in the FTAI groups had a higher overall PR (proportion pregnant as per the entire group) than the EDAI group (34.6% vs. 23.2%; P = 0.003), however, conception rate (PR of heifers submitted for AI) tended to favor the estrus detection group (34.6% vs. 44.1%; P = 0.059). The cost per AI calf born was estimated to be $267.67 and $291.37 for the FTAI and EDAI groups, respectively. It was concluded that in Brahman heifers typical of those annually mated in northern Australia FTAI compared with EDAI increases the number of heifers pregnant and reduces the cost per calf born.

Lack of complete regression of the Day 5 corpus luteum after one or two doses of PGF2α in nonlactating Holstein cows

The early corpus luteum (CL) (before Day 6) does not regress after a single PGF2α treatment. We hypothesized that increasing PGF2α dose or number of treatments would allow regression of the early CL (Day 5). Nonlactating Holstein cows (N = 22) were synchronized using the Ovsynch protocol. On Day 5 (Day 0 = second GnRH treatment), cows were assigned to: (1) control (N = 5): no further treatment; (2) 1PGF (N = 6): one dose of 25 mg PGF2α; (3) 2PGF (N = 5): two doses of 25 mg PGF2α (50 mg) given 8 hours apart (second PGF2α on Day 5 at the same time as the other PGF2α treatments); (4) DPGF (N = 6): double dose of 25 mg PGF2α (50 mg) given on Day 5. Blood samples were collected to monitor progesterone (P4) profiles in two periods. In the first period (0 to 24 hours), there were effects of treatment (P = 0.01), time (P < 0.01), and an interaction of treatment and time (P = 0.02). Group 1PGF versus control was different only at 12 hours (P = 0.02). Cows treated with DPGF were different than control at 4 hours (P = 0.04), 12 hours (P < 0.01), and 24 hours (P < 0.01). Only cows treated with 2PGF had lower P4 than control during the entire period and low P4 (0.37 ± 0.17 ng/mL) at 24 hours, usually indicative of luteolysis. In the second period (Day 5 to 15 of the cycle), there were effects of treatment (P < 0.01), time (P < 0.01), and interaction of treatment and time (P = 0.002). Group 1PGF was not different than control from Day 5 to 13 and P4 was greater than control on Day 14 (P = 0.01) and 15 (P < 0.01). Circulating P4 in DPGF cows was lower than control from Day 7 (P = 0.05) through 12 (P < 0.01). Likewise, there were differences between control and 2PGF from Day 7 to 13, but not on Day 14 and 15. On Day 15, all PGF2α-treated groups had circulating P4 consistent with an active CL. Ultrasound evaluation confirmed that no CL from any group completely regressed during the experiment and no new ovulations occurred to account for functional CL later in cycle. In summary, a double dose of PGF2α (twice on Day 5 or 8 hours apart) can dramatically decrease P4, consistent with classical definitions of luteolysis; however, these CL recover and become fully functional. Thus, the Day 5 CL of mature Holstein cows do not regress even to two doses of PGF2α.

Effects of 1 or 2 treatments with prostaglandin F2α on subclinical endometritis and fertility in lactating dairy cows inseminated by timed artificial insemination

The objectives of the current study were to investigate the efficacy of PGF2α as a therapy to reduce the prevalence of subclinical endometritis and improve pregnancy per artificial insemination (P/AI) in cows subjected to a timed artificial insemination (AI) program. A total of 1,342 lactating Holstein dairy cows were allocated randomly at 25±3d in milk (DIM) to remain as untreated controls (control, n=454) or to receive a single PGF2α treatment at 39±3 DIM (1PGF, n=474) or 2 treatments with PGF2α at 25±3 and 39±3 DIM (2PGF, n=414). All cows were enrolled in the double Ovsynch program at 48±3 DIM and were inseminated at 75±3 DIM. A subset of 357 cows had uterine samples collected for cytological examination at 25±3, 32±3, and 46±3 DIM to determine the percentage of polymorphonuclear leukocytes (PMNL). Subclinical endometritis was defined by the presence of ≥5% PMNL. Vaginal discharge score was evaluated at 25±3 DIM and used to define the prevalence of purulent vaginal discharge. Body condition score was assessed at 25±3 DIM. Pregnancy was diagnosed 32d after AI and reconfirmed 28d later. At 32±3 DIM, the prevalence of subclinical endometritis was reduced by treatment with PGF2α at 25±3 DIM in 2PGF (control=23.5% vs. 1PGF=28.3% vs. 2PGF=16.7%); however, this benefit disappeared at 46±3 DIM, and 14% of the cows remained with subclinical endometritis. One or 2 treatments with PGF2α did not influence P/AI on d 32 or 60 after timed AI, which averaged 39.9 and 35.2%. Similarly, treatment with PGF2α had no effect on pregnancy loss between 32 and 60d of gestation (11.9%). Cows diagnosed with both purulent vaginal discharge and subclinical endometritis had the lowest P/AI and the highest pregnancy loss compared with those diagnosed with only 1 of the 2 diseases or compared with cows having no diagnosis of uterine diseases. Interestingly, subclinical endometritis depressed P/AI and increased pregnancy loss only when it persisted until 46 DIM. On d 32 after AI, cows not diagnosed with subclinical endometritis and those that resolved subclinical endometritis by 46 DIM had greater P/AI than those that remained with subclinical endometritis at 46 DIM (45.4 and 40.0 vs. 25.0%, respectively). Similar to P/AI, cows not diagnosed with subclinical endometritis and those that resolved subclinical endometritis by 46 DIM had less pregnancy loss than those with subclinical endometritis at 46 DIM (9.6 and 13.5 vs. 43.9%, respectively). One or 2 treatments with PGF2α before initiation of the timed AI program were unable to improve uterine health, P/AI, and maintenance of pregnancy in lactating dairy cows. Cows diagnosed with both purulent vaginal discharge and subclinical endometritis had the greatest depressions in measures of fertility at first AI, particularly when subclinical endometritis persisted in the early postpartum period.