Luteal Profile Research Articles

Assessment of plasma melatonin profile in summer anestrous buffaloes exhibiting differential fertility following melatonin implants treatment

Plasma melatonin vis-a-vis anestrus or estrus status of buffaloes during summer or winter season (n=50 in each group) suggested its impact on reproductive axis as plasma melatonin activity tended to be higher (P>0.05) in buffaloes exhibiting estrus compared to their anestrous counterparts irrespective of season. The differential reproductive status of these buffaloes was confirmed by history as well as differences (P<0.05) in diameter of largest follicle and luteal profile. Further, for evaluating the impact of melatonin treatment during summer season on reproductive axis, 132 anestrous buffaloes were subcutaneously inserted 2x4 mm absorbable slow-release melatonin implants (18 mg/50 kg b wt) at the base of left ear and 60 buffaloes were used as control. In these buffaloes, ovarian ultrasonography and jugular vein blood sampling was carried out at 7-day interval till day 35 post-treatment or till ovulation, whichever was earlier. Control and implanted buffaloes were subjected to artificial insemination (AI) at overt or induced estrus followed by pregnancy diagnosis at day 90 post-AI. In treatment group, an increase (P<0.05) in plasma melatonin was recorded in all the buffaloes, exhibiting differential fertility status, during post-treatment study period compared to their pre-treatment and control group values. However, within treatment group, there was no difference (P>0.05) in plasma melatonin between ovulatory or non-ovulatory as well as between pregnant or non-pregnant counterparts. Moreover, plasma melatonin within control buffaloes remained similar (P>0.05) throughout the study period irrespective of differential exhibition of fertility. It can be concluded that factors other than circulating melatonin are also involved in the display of differential fertility in terms of initiation of ovarian cyclicity/ovulation or ability to conceive in summer anestrous buffaloes.

The thermographic monitoring in early pregnancy detection in Holstein cows and heifers

This study aimed to conduct a comprehensive investigation to demonstrate early pregnancy detection using thermography in heifers and cows. A total of 60 heifers (n: 30) and cows (n: 30) were divided into two groups as pregnant (n: 15 heifers, n: 15 cows) and non-pregnant (n: 15 heifers, n: 15 cows) according to the day 28 of gestation. Thermographic images were taken from the vulvar and anal regions on alternate days from D0 to D20. Blood samples were collected to determine estrogen and progesterone concentrations. The mean temperature difference between the anal and vulvar regions (ΔT °C) was used in the statistical analyses. Based on the hormonal profiles, no abnormalities were observed for follicular waves or luteal profiles in heifers and cows. The ΔT °C values between heifers and cows and between days were statistically significant (P < 0.001). In thermographic analyses, the differences observed in other main effects and interactions of the group, sampling time, and pregnancy were not statistically significant (P > 0.05). In receiver operating characteristic (ROC) analyses, it was concluded that the ΔT °C value of ≤ 2.9 °C (100% Se - 61.9% Sp) was highly correlated with pregnancy diagnosis in cows on day six after artificial insemination (AI) (P < 0.001). In conclusion, it was determined that the clinical application of thermography can be used for the detection of pregnancy on day six after AI in cows. However, further studies are needed to determine heifers' thermographic characteristics and profiles.

Intensity of estrus expression – valuable obvious determinant of fertility in Bos indicus cows

This study aimed to characterize estrus response and to establish relationships between intensity of estrus, preovulatory follicle (POF) size and estradiol (E2) concentrations on day of AI, luteal profiles and pregnancy outcome in lactating Hariana breed of cows. 200 cyclic cows were subjected to Ovsynch (n = 54) and Pre-OV treatment (n = 146). Ovsynch: Buserelin acetate (BA; 10 µg), Cloprostenol (500 µg) and BA (10 µg) were injected i.m. on day 0, 7 and 9, respectively, irrespective of treatment. Pre-OV: BA (10 µg) and Cloprostenol (500 µg) was also injected i.m. simultaneously 7 days prior to initiate Ovsynch. On the basis of estrus behavior, the cows were classified into three groups: weak, moderate and intense. Artificial insemination performed at 18–24 hours after 2nd BA of Ovsynch in both treatments. The average duration of estrus did not differ (p > 0.05) between Ovsynch and Pre-OV treatment. A positive correlation was observed between estrus response and POF size, concentration of E2 on day of AI and luteal profiles on day 12 post-AI. First service conception rate was higher in cows exhibited intense (45.46%) and moderate (42.56%) estrus response than weak (28.57%) estrus response. In conclusion, intensity of estrus expression could be considered as important determinant for deciding pregnancy outcomes in Bos indicus cows.

Effect of melatonin implantation prior to ovsynch plus cidr protocol on subsequent ovarian activity and pregnancy rate in summer anestrous Murrah buffaloes

For assessing the impact of melatonin pre-treatment in summer anestrous Murrah buffaloes on subsequent reproductive activity of a fixed time artificial insemination (FTAI) protocol, 83 anestrous Murrah buffaloes were subcutaneously inserted 2x4 mm size absorbable melatonin (MT) implants (18 mg/50 kg b wt) at the base of left ear and 38 Murrah buffaloes were used as non-implanted controls. On day 35 post-MT, the treatment and control group Murrah buffaloes were subjected to FTAI protocol (Ovsynch plus CIDR). Ovarian ultrasonography and jugular vein blood sampling was carried out on day 7 and 10 of protocol and on day 7-post AI. Overall pregnancy rate on day 90 post-AI in MT group was higher compared to control group (55.4 vs 31.6%, P&lt;0.05), along with the higher (P&gt;0.05) plasma progesterone on day 7 of FTAI protocol in Murrah buffaloes of the former group which conceived subsequently compared to their non-pregnant counterparts. Moreover, MT group had higher (P&gt;0.05) increase in dominant follicle diameter between day 7 and 10 of protocol compared to control group. On day 7 post-AI, the luteal profile in pregnant murrah buffaloes of MT group was better (P&lt;0.05) compared to their counterparts in control group (CL: 14.80±0.70 vs 10.82±0.46 mm, P4: 1.54±0.07 vs 1.04±0.08 ng/ml). In conclusion, melatonin pre-treatment in summer anestrous Murrah buffaloes could be associated with better luteal activity and higher pregnancy rate in the Ovsynch+CIDR protocol.

5d CIDR-Heatsynch improves the circulatory estradiol levels, estrus expression and conception rate in anestrus buffalo (Bubalus bubalis)

The present study aimed to investigate whether increasing estradiol (E2) during preovulatory period would increase estrous expression, luteal profiles and conception rate in 5d CIDR based timed AI protocol. A total 156 anestrus buffalo allocated (78 per group) to either 5d CIDR-Cosynch (d-5: CIDR + GnRH; d0: PGF2α+CIDR removal; 72 h post-CIDR removal: GnRH) or 5d CIDR-Heatsynch (d-5: CIDR + GnRH; d0: PGF2α+CIDR removal; 24 h post-CIDR removal: estradiol benzoate) group. All the buffaloes inseminated at 72 and 84 h post-CIDR removal. A subset of buffalo (n = 58) were subjected to examination of the follicle diameter and luteal profile during protocol, post-AI on days 5 and 12. The buffalo in 5d CIDR-Heatsynch had greater (p < .05) E2 concentrations, estrus induction and increasing trend (p < .08) for conception rate (57.7% vs. 43.6%) than 5d CIDR-Cosynch. The percentage of pregnant buffalo that exhibited estrus signs was greater (p < .01) in 5d CIDR-Heatsynch than 5d CIDR-Cosynch. Positive correlation (p < .01) was observed between POF and E2 concentrations; POF and CL diameter, CL diameter and P4 concentrations. Estrus response and P4 concentrations were indicators of probability of pregnancy. In conclusion, 5d CIDR-Heatsynch tended to improve conception rate. The estrus expression and P4 concentrations (d5 and 12 post-first-AI) is the indicator of probability of pregnancy in buffalo.

Presynchronization with simultaneous administration of GnRH and prostaglandin F2α (PGF2α) 7 days prior to Ovsynch improves reproductive profile in Hariana zebu cow

This study is aimed at assessing the impact of simultaneous administration of GnRH and prostaglandin F2α (PGF2α) 7days prior to Ovsynch in Hariana cow. Two hundred cyclic cows (> 4months postpartum) were assigned to control (n = 54) and pre-OV (n = 146). As per Ovsynch protocol, buserelin acetate (10μg), cloprostenol (500μg), and buserelin acetate (10μg) were injected i.m. on days 0, 7, and 9, respectively, in cows irrespective of treatment. But in pre-OV cows, buserelin acetate (10μg) and cloprostenol (500μg) were also injected i.m. simultaneously 7days prior to initiate the Ovsynch protocol. Artificial insemination was performed between 18 and 24h after the 2nd GnRH of Ovsynch in both treatments. Ultrasonography and blood sampling for hormonal analysis were done on each day of treatment, on day of AI, and 12days post-AI. Pre-OV treatment resulted to increased (45.20% vs 29.62%; P < 0.05) pregnancy outcomes and higher (P < 0.01) ovulation rate to first GnRH of Ovsynch than control. Cows showing complete luteolysis in response to PGF2α of Ovsynch were also higher (P < 0.05) in pre-OV than control. Greater (P < 0.05) synchronization rate was recorded in pre-OV than control (86.76% and 68.75%). The circulating concentrations of estradiol on day of AI and progesterone on day 12 post-AI were higher (P < 0.01) in cows diagnosed pregnant than non-pregnant in both control and pre-OV treatment. In conclusion, simultaneous administration of GnRH and PGF2α 7days before Ovsynch improved the synchronization rate and luteal profile in terms of CL area and hence resulted in higher conception rate in Hariana zebu cow.

Impact of Doublesynch and Ovsynch Protocols, Preovulatory Follicle, Estradiol and Luteal Profiles on Fertility in Cyclic Murrah Buffaloes during Breeding and Compromised-Breeding Season

The present study designed to evaluate the efficacy of Doublesynch and Ovsynch estrus synchronization protocols, preovulatory follicle (POF) and luteal profile in cyclic Murrah buffaloes (n=83) in summer and winter season at farm and field level. In Ovsynch protocol, buffaloes were administered (i.m.) two injections of 10µg, Buserelin acetate on days 0 and 9, and an injection of 500µg, Cloprostenol on day 7. In Doublesynch protocol, an additional injection (i.m.) of 500µg, Cloprostenol 2 days before the start of Ovsynch protocol was administered. The ultrasonography (USG) and blood sampling was performed on each day of treatment, on day of estrus and 10 days post-AI. The conception rate in Ovsynch treatment group during summer and winter season was 20% and 27.8%, respectively and in Doublesynch groups, it was 40% and 48% in summer and winter season, respectively. Overall mean diameter of POF on day of estrus was larger (p&lt;0.05) in pregnant than non-pregnant buffalo (14.6 ± 0.4 vs 12.7 ± 0.3 mm, respectively). The POF diameter was positively correlated with estradiol concentration on the day of AI and corpus luteum (CL) diameter on day 10 post-AI (E2: r=0.84, p&lt;0.05; CL: r=0.72, p&lt;0.05). Doublesynch group’s buffaloes had higher (p&lt;0.05) ovulation rate after first GnRH injection than Ovsynch group than Ovsynch in both season. It was concluded that Doublesynch protocol can be used as estrus synchronization protocol in both seasons to achieve acceptable conception rate with size of preovulatory follicle greatly affecting the fertility by influencing estradiol levels and luteal profile in buffalo.

Pre-ovulatory follicle size at induced estrus and post-ovulatory luteal profiles, and pregnancy rate in Murrah buffalo (Bubalus bubalis) using estradiol-17β + CIDR protocol

Pre-ovulatory follicle size at induced estrus and post-ovulatory luteal profiles, and pregnancy rate in Murrah buffalo (Bubalus bubalis) using estradiol-17β + CIDR protocol

Effects of melatonin supplementation prior to Ovsynch protocol on ovarian activity and conception rates in anestrous Murrah buffalo heifers during out of breeding season

Buffalo heifers have tendency to show anestrus during summer season. Melatonin has been used for correcting summer dependent anestrous via inducing resumption of ovarian activity. Therefore, the investigation was conducted to compare efficacy of melatonin for induction of estrus and conception rate with Ovsynch protocol in summer anestrous Murrah buffalo heifers. Thirty, summer anestrous Murrah buffalo heifers were selected and divided into two groups- treatment (n = 20; 12 melatonin implants) and control (n = 10; no treatment). On day 28 post-implant insertion, animals of both the groups were subjected to Ovsynch protocol. Blood sampling and ovarian ultrasonography were conducted to measure plasma melatonin, progesterone concentration and ovarian dynamics, respectively. No animal in either group showed estrus during first 28 days post-implant insertion. However, estrus induction rate was 100% after Ovsynch protocol in both groups. As compared to controls, treatment group exhibited higher (p < 0.05) plasma melatonin on days 1, 4, 8, 15, 22 and 28 post-melatonin, with highest concentration on day 4. The progesterone concentration increased (p < 0.05) on days 15 and 22 post-melatonin treatment. The treatment group had larger (p < 0.05) preovulatory follicle on day of AI, subsequently developed larger (p < 0.05) corpus luteum and higher plasma progesterone concentrations by day 12 post-AI as compared to the control group. The overall conception rate was 50 and 20% in treatment and control groups, respectively. In conclusion, melatonin treatment along with Ovsynch protocol improved the luteal profiles as well as the conception rate in buffalo heifers when compared with animals treated with Ovsynch protocol alone during summer season.

Effects of preovulatory follicle size on estradiol concentrations, corpus luteum diameter, progesterone concentrations and subsequent pregnancy rate in buffalo cows (Bubalus bubalis)

The present study was undertaken to investigate the effects of preovulatory follicle (POF) size on estradiol concentrations, luteal profile (CL diameter and progesterone concentration) and subsequent pregnancy rate in Murrah buffalo cows. The buffalo cows (n = 49) were synchronized for estrus by two doses of PGF2α given 11 days apart. The buffalo cows were inseminated during standing estrus and again after 24 h. Ovaries were scanned at estrus and 24 h intervals until ovulation, thereafter on days 5, 12 and 16 post-ovulation to examine the POF and CL diameter. Size of POF at estrus was divided into three categories; I: 10 to ≤12; II: >12.0 to ≤14.0; III: >14.0–16.0 mm. Blood samples were collected for estradiol (on day of estrus) and progesterone concentration (on days 5, 12 and 16). The estradiol concentrations were greater (P < 0.05) in category II than category I with the greatest (P < 0.05) concentrations estimated in category III. A positive correlation (P < 0.05) between POF and progesterone concentration, CL diameter and progesterone concentration was observed on all sampling day. Pregnant buffalo cows exhibited greater (P < 0.05) plasma progesterone as compared with their non-pregnant counterpart. Greater pregnancy rates were observed with an increased size of POF (χ2 = 2.9, P > 0.05). It was concluded that the POFs having diameters between 12 and 16 mm are mature enough to be transformed into CL of such optimum diameter and can secrete optimum progesterone concentrations that can sustain the pregnancy in Murrah buffalo cows.

Mastitis outcomes on pre-ovulatory follicle diameter, estradiol concentrations, subsequent luteal profiles and conception rate in Buffaloes

The objectives of this study was to investigate the outcome of mastitis, in its clinical or subclinical forms, on the mean diameter of pre-ovulatory follicle (POF), plasma estradiol concentration on the day of estrus, subsequent luteal profile and subsequent conception rate in buffaloes. Sixty dairy buffalo (Bubalus bubalus) conducted in this study were divided into three groups {healthy (H), n=20; subclinical mastitis (SCM), n=18; and clinical mastitis (CM), n=22}. Ultrasonography of ovaries revealed that mean diameter of POF was larger (P<0.05) in H buffalo (14.35mm) compared to SCM (12.40mm) and CM (10.25mm). Also, plasma estradiol concentration on the day of estrus was higher (P<0.05) in H buffalo compared to SCM and CM counterparts; 34.95 vs. 32.87 and 27.50pg/ml, respectively. Besides, positive correlation was observed between the POF diameter with plasma estradiol concentration in H, SCM and CM buffaloes (r=0.64, 0.74, 0.72 respectively, P<0.05). Moreover, positive correlations (P<0.01) were found on days 9, 12, 16, and 21 post-ovulation between POF diameter and luteal profile. Thus, the conception rate in H buffalo was higher (P<0.05) compared with SCM and CM counterparts; 55% vs. 38.89 and 18.18%, respectively. In conclusion, mastitis in its clinical or subclinical forms disrupts the functioning of the pre-ovulatory follicle on the day of estrus, associated with low follicular estradiol production, resulting in suppression to subsequent luteal profile leading to substantial decrease in pregnancy consequence of buffaloes.

Impact of Buserelin Acetate or hCG Administration on the Day of First Artificial Insemination on Subsequent Luteal Profile and Conception Rate in Murrah Buffalo (Bubalus bubalis).

This study was designed to investigate the impact of buserelin acetate (BA) or human chorionic gonadotropin (hCG) administration on the day of first artificial insemination (AI) on subsequent luteal profile (diameter of corpus luteum (CL) and plasma progesterone) and conception rate in Murrah buffalo. The present experiment was carried out at two locations in 117 buffalo that were oestrus-synchronized using cloprostenol (500μg) administered (i.m.) 11days apart followed by AI during standing oestrus. Based on treatment (i.m.) at the time of AI, buffalo were randomly categorized (n=39 in each group) into control (isotonic saline solution, 5ml), dAI-BA (buserelin acetate, 20μg) and dAI-hCG (hCG, 3000 IU) group. Out of these, 14 buffalo of each group were subjected to ovarian ultrasonography on the day of oestrus to monitor the preovulatory follicle and on days 5, 12, 16 and 21 post-ovulation to monitor CL diameter. On the day of each sonography, jugular vein blood samples were collected for the estimation of progesterone concentrations. All the buffalo (n=117) were confirmed for pregnancy on day 40 post-ovulation. The conception rate was better (p<0.05) in dAI-BA (51.3%) and dAI-hCG (66.7%) groups as compared to their control counterparts (30.8%). Furthermore, the buffalo of dAI-hCG group had improved (p<0.05) luteal profile, whereas the buffalo of dAI-BA group failed (p>0.05) to exhibit stimulatory impact of treatment on luteal profile when compared to control group. In brief, buserelin acetate or hCG treatment on the day of first AI leads to an increase in conception rate; however, an appreciable impact on post-ovulation luteal profile was observed only in hCG-treated Murrah buffalo.

135 SHORT-TERM OVARIAN EFFECTS OF UNILATERAL OVARIECTOMY IN COWS

Classical studies established that the removal of one of the paired organs produces a compensatory effect on the remaining organ. In the bovine ovary this aspect has not been examined in detail. We took advantage of follicular and luteal profiles from a previous study to retrospectively examine the effects of ovariectomy before and after ovulation on follicular dynamics of the remaining ovary in cattle. To characterise the prevalence and distribution of tyrosine kinase receptor A in the bovine ovary, the original design involved unilateral ovariectomy of cows at different stages of the periovulatory period. For the purposes of the present study, we combined data into 2 groups, a preovulatory group (n = 6 cows) and a post-ovulatory group (n = 5 cows), to provide sufficient data for statistical interpretation. The cows were examined daily by transrectal ultrasonography to determine the ovarian status. For the preovulatory group, a luteolytic dose of prostaglandin was administered when the dominant follicle of the second follicular wave reached ≥10 mm, and the ovary containing the dominant follicle was removed within 48 h. For the post-ovulatory group, ovariectomy was performed on the ovary containing the newly formed corpus luteum between Days 2 to 6 (Day 0 = ovulation). Unilateral ovariectomy was performed by colpotomy under caudal epidural anaesthesia using a chain ecraseur. After ovariectomy, cows were examined daily by ultrasonography from ovariectomy to the completion of an interovulatory interval (period between 2 ovulations). Single-point data were compared between groups by t-test, and binomial data were compared between groups by Fisher’s exact test. Double ovulations were detected in 3/6 ovariectomized in the preovulatory period and 2/5 ovariectomized in the post-ovulatory period. The first ovulation after ovariectomy tended to occur earlier in the preovulatory group than in the post-ovulatory group (P = 0.08), which was attributed primarily to the development of oversized persistent dominant follicles (~20 mm in diameter for ≥7 days in absence of a corpora lutea) in 2 of 5 cows in the post-ovulatory ovariectomy group. The interovulatory interval after ovariectomy was shorter in the post-ovulatory group than in the preovulatory group (14.6 ± 0.3 v. 20.3 ± 0.6 days; P = 0.01). No distinct patterns were detected in follicular and luteal dynamics between the pre- and post-ovulatory ovariectomy groups. The number of follicles ≥3 mm detected by ultrasonography was greater in the post-ovulatory ovariectomy group than in the preovulatory group on Days 6, 7, 8, and 16 of the first interovulatory interval after ovariectomy. In conclusion, results of this retrospective study support the concept that follicular and luteal effects of removal of one ovary are influenced by the timing of ovariectomy relative to ovulation. A prospective study involving a comparison of ovarian dynamics of the same cows before and after unilateral ovariectomy will provide a better understanding of the disruption that take place and the mechanisms controlling it. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

Impact of buserelin acetate or hCG administration on day 5 post-ovulation on subsequent luteal profile and conception rate in Murrah buffalo (Bubalus bubalis)

The present study aimed to establish the impact of buserelin acetate or hCG administration on day 5 post-ovulation on subsequent luteal profile and conception rate in buffalo. The buffalo (n=45) were subjected to an estrous synchronization protocol (synthetic analog of PGF2α administered, through intramuscular route, 11 days apart), followed by artificial insemination (AI) during mid to late estrus. On day 5 post-ovulation, buffalo were administered (i.m.) normal saline (Control, n=14), buserelin acetate (20μg, d5-BA, n=14) or human chorionic gonadotropin (3000IU, d5-hCG, n=17). Ovarian ultrasonography was conducted on the day of induced estrus and on days 0, 5, 12, 16 and 21 post-ovulation to assess preovulatory follicle or corpus luteum (CL) diameter. Also, on these days, jugular vein blood sampling was conducted for the estimation of plasma progesterone. First service conception rate was greater (χ2=5.18, P>0.05) in d5-BA and d5-hCG groups (71.4% and 47.1%, respectively) as compared to control (28.6%). Both treatment groups had a greater (P<0.05) CL diameter and plasma progesterone during the post-treatment period in comparison to that control treatment group. Treatment-induced accessory CL formation was observed in 92.9% and 76.5% buffalo of d5-BA and d5-hCG groups, respectively. In conclusion, buserelin acetate and hCG administration on day 5 post-ovulation leads to accessory CL formation that may have a role in enhancing conception rate.

Detection of estrous behavior in buffalo heifers by radiotelemetry following PGF2α administration during the early or late luteal phase

This study examined the usefulness of radiotelemetry for estrous detection in buffalo heifers and the impact of prostaglandin F2α (PGF2α) administration during the early or late luteal phase on estrous behavior and ovulatory follicle variables. Induction of estrus with PGF2α at a random stage of the estrous cycle was followed by the arbitrary division of heifers into groups receiving a second dose of PGF2α during either the early (n=33) or late (n=17) luteal phase (6–9 or 11–14 days after estrus, respectively) for the induction of synchronized estrus. The electronic detection of synchronized estrus by radiotelemetry was confirmed using ultrasonography every 6h until ovulation. Radiotelemetry was 90% efficient and 100% accurate for estrous detection. Intervals between the PGF2α dose and the beginning of synchronized estrus (40.7±10.9 vs. 56.7±12.8h) or ovulation (70.0±11.3 vs. 85.6±12.5h) were shorter (P<0.05) for heifers receiving PGF2α during the early luteal phase. PGF2α administration during the early or late luteal phase produced similar (P>0.05) results for the duration of estrus, the intervals from the beginning or end of estrus to ovulation, the number and duration of mounts per estrus, the duration of mounts, the diameter of the ovulatory follicle and the luteal profile on day 5 after estrus. In conclusion, radiotelemetry was a suitable tool for the efficient and accurate detection of estrus in buffalo heifers. Treatment with PGF2α during the early luteal phase had a shorter interval to synchronized estrus and ovulation; however, estrous behavior, ovulatory follicle dynamics and subsequent luteal activity were similar following PGF2α administration during the early or late luteal phase.

Improvement of conception rate in postpartum flaxseed supplemented buffalo with Ovsynch + CIDR protocol

The present study was conducted on lactating Murrah buffalo to assess the effect of crushed flaxseed (a source of omega-3 fatty acids) supplementation (300g/100kg bwt/day for 60 days), over and above the routine feed, on luteolytic signal (PGF2α), luteal function (progesterone) and conception rate. In first experiment, on day 50 post-calving, six non-supplemented buffalo were treated to synchronize time of ovulation using an Ovsynch+Controlled Internal Drug Release (CIDR) protocol followed by intravenous oxytocin treatment (OT; 100IU) on day 15 post-ovulation. Blood samples were collected at 15min interval, 1h before to 4h after OT challenge. Thereafter, the same buffalo were supplemented with flaxseed, treated to synchronize time of ovulation starting on day 35 post-supplementation using the same protocol and subjected to OT treatment and blood sampling on day 15 post-ovulation. The PGF2α response was measured as the venous concentration of 13,14-dihydro-15-keto PGF2α (PGFM). The mean hourly concentration of PGFM subsequent to flaxseed supplemented was less (P<0.05) than in the pre-supplementation period at all the occasions. Flaxseed supplementation did not affect plasma fatty acids and other plasma metabolites except for an increase (P<0.05) in plasma cholesterol and plasma alanine transaminase. In the second experiment, 31 buffalo were randomly assigned to a control (n=16) and flaxseed supplemented (n=15) group. The latter group was supplemented with flaxseed starting from day 15 post-calving. On day 50-post-calving, buffalo of both groups were treated to synchronize time of ovulation among animals as described for the first experiment followed by artificial insemination (AI). Post-AI luteal phase plasma progesterone was greater (P<0.05) in the supplemented group compared to controls. Conception rate on day 63 post-AI was 66.7% in supplemented and 31.2% in controls (P<0.05). The present study indicated the beneficial impact of dietary supplementation of crushed flaxseed on conception rate through attenuation of luteolytic signal and improvement in post-breeding luteal profile.

Impact of buserelin acetate or hCG administration on day 12 post-ovulation on subsequent luteal profile and conception rate in buffalo (Bubalus bubalis)

The present study investigated the impact of gonadotropic hormone administration on day 12 post-ovulation on subsequent luteal profile and conception rate in buffaloes. All the buffaloes (n=48) were estrus synchronized by a synthetic analogue of prostaglandin F2α (PGF2α), administered 11 days apart, followed by insemination during mid to late estrus. To examine the effect of mid-luteal phase hormonal treatment, buffaloes were randomly divided into control (normal saline, n=14), d12-BA (buserelin acetate, 20μg, n=17) and d12-hCG (hCG, 3000IU, n=17) groups. Ovaries were scanned on the day of induced estrus to measure the preovulatory follicle (POF) diameter and on days 5, 12, 16 and 21 post-ovulation to examine the alterations in corpus luteum (CL) diameter. On the day of each sonography, blood samples were collected for the estimation of plasma progesterone. In treatment groups, luteal profile (CL diameter and plasma progesterone) on day 16–21 post-ovulation was better (P<0.05) as well as first service conception rate was higher (52.9% in each treatment group vs. 28.6%, P>0.05) compared to controls. All the pregnant buffaloes exhibited higher (P<0.05) plasma progesterone on various post-ovulation days than their respective non-pregnant counterparts. Treatment-induced accessory corpus luteum (ACL) formation was observed in 58.8 per cent and 70.6 per cent buffaloes of d12-BA and d12-hCG group, respectively, that also had higher (P<0.05) plasma progesterone compared to controls. Compared to the spontaneous CL, the diameter of ACL was less (P<0.05) in the treatment groups. In conclusion, buserelin acetate and hCG administration on day 12 post-ovulation leads to accessory CL formation, improves luteal profile and consequently increases conception rate in buffaloes.

Impact of initiating a PGF2α-GnRH fixed-time AI protocol at the late luteal phase on reproductive performance of repeat-breeder crossbred dairy cattle

The objectives of this study were to document ovarian and endocrine responses as well as pregnancy establishment following the treatment of repeat-breeder crossbred dairy cattle with a prostaglandin F2a-gonadotropin releasing hormone (PGF2a-GnRH) fixed-time artificial insemination (AI) protocol at the late luteal phase. Cattle (15) were administered PGF2a (500 µg cloprostenol) on day 16 of the estrous cycle, followed by GnRH analogue (20 µg buserelin) 5 days later. About 24 h after GnRH, AI was carried out in all the cattle. Transrectal ovarian ultrasonography was carried out at the time of PGF2a administration, at AI and on days 5, 16 and 21 post-AI. Plasma progesterone was assayed with solid- phase radioimmunoassay. All the cattle responded to treatment with a luteolytic dose of PGF2a. On the day of AI, large follicles of 15.94±0.60 (12.7–22.0) mm diameter were observed in all the cattle. The presence of active luteal profile on day 5 post-AI confirmed the occurrence of ovulation in all the cattle. Post-treatment first service conception rate was appreciable (66.7%) in cattle with history of repeat breeding. Repeat-breeder cattle failing to conceive after hormonal treatment had suprabasal plasma progesterone on the day of AI in comparison to their non-conceiving counterparts. In conclusion, initiation of PGF2a-GnRH protocol based fixed-time AI protocol at the late luteal phase is highly successful for inducing ovulation in all the repeat-breeder cattle, and yielded an appreciably high conception rate.

Impact of norgestomet supplementation during early luteal phase on subsequent luteal profiles and conception rate in buffalo: a preliminary study

The current study was aimed to establish the impact of progesterone supplementation (norgestomet progestagen) between days 4 to 10 post-ovulation on subsequent luteal profile and conception rate in buffaloes. The 28 Murrah buffaloes of second to fourth parity, having normal reproductive organs, were estrus synchronized by double PGF(2α) protocol at 11 days apart. The buffaloes were inseminated during mid- to late estrus and thereafter repeated at 24 h interval. The buffaloes were randomly assigned into two groups: (1) control (no treatment, n = 14) and (2) treatment group (CRESTAR ear implant, n = 14). The CRESTAR ear implant (3 mg, norgestomet progestagen) was inserted subcutaneous between days 4 to 10 post-ovulation. The ovaries were scanned at estrus and thereafter on days 4, 10, 16, 21, and 40 post-ovulation to examine the preovulatory follicle (POF) and corpus luteum (CL) diameter. Each ultasonography was followed by blood sample collection for analysis of plasma progesterone concentrations following ovulation. The conception rate was similar (p > 0.05) between treated and control buffaloes. The pregnant buffalo of the control group had larger (p < 0.05) POF diameter than nonpregnant counterparts. The CL diameter was similar (p > 0.05) in both treated and untreated control as well as in their pregnant and nonpregnant buffaloes of the respective groups. The plasma progesterone concentrations were higher (p < 0.05) in the treatment group on the day 10 post-ovulation as compared to the control buffaloes. It is concluded that norgestomet supplementation had no impact on conception rate and CL diameter but enhances the plasma progesterone concentrations following treatment in buffaloes.

Impact of pre-ovulatory follicle diameter on plasma estradiol, subsequent luteal profiles and conception rate in buffalo (Bubalus bubalis)

The present study was designed to investigate the impact of pre-ovulatory follicle (POF) diameter on the day of estrus on plasma estradiol concentration, subsequent luteal profile (corpus luteum, CL, diameter and plasma progesterone concentration) and conception rate in buffaloes. Twenty-eight buffaloes were synchronized with synthetic analogue of prostaglandin F2α (PGF2α) administered 11 days apart. Transrectal ultrasonography and jugular vein blood sampling was carried out on the day of estrus and on days 0 (day of ovulation), 5, 12, 16 and 21 post-ovulation. Out of 28 buffaloes, 11 (39.3%) were diagnosed pregnant on day 40 post-ovulation. Retrospective analysis revealed that the buffaloes getting pregnant had larger (p<0.05) POF diameter. In fact, all the buffaloes (n=5/5) having POF diameter between >14 and 16mm conceived, whereas, conception rate in buffaloes with POF diameter between >12 and ≤14mm (n=6/17) or <12mm (n=0/6) was 35.3% and 0.0%, respectively. A positive correlation (r=0.57, p<0.05) was observed between POF diameter and plasma estradiol concentration at estrus. On day 5 post-ovulation, luteal profile was positively correlated (CL: r=0.34, p<0.05; plasma progesterone concentration: r=0.27, p>0.05) with POF diameter. Further, on the same day, plasma progesterone concentration was positively correlated (r=0.47, p<0.05) with CL diameter, however, this correlation was absent (r=0.05, p>0.05) during the subsequent luteal phase. Nevertheless, the post-ovulation luteal profile of pregnant buffaloes was higher (p<0.05) compared to non-pregnant counterparts. In conclusion, the diameter of POF in buffaloes has positive impact on plasma estradiol concentration at estrus, post-ovulation luteal profile and conception rate. The diameter of CL can be used as an indicator of luteal function at early but not at mid or late luteal phase of estrus cycle in buffaloes.