Treatment alternatives to induce follicular wave emergence for timed-AI in lactating dairy Cows.

Two experiments evaluated the effect of different hormonal treatments to synchronize follicle wave emergence on follicle dynamics and pregnancies per AI (P/AI) in estradiol (E2)/progesterone (P4) timed-AI (TAI) protocols in lactating dairy cows. In Experiment 1, lactating, primiparous Holstein cows (n = 36) received a P4 releasing device (Day 0) and were allocated at random to one of the following three treatment groups: Group EB received 2 mg E2 benzoate (EB) intramuscularly (i.m.), Group EB + GnRH received 2 mg EB+20 µg buserelin (GnRH) i.m., or Group EB + P4 received 2 mg EB + 100 mg of injectable P4 (iP4) in oil i.m. All cows received 0.150 mg D-Cloprostenol on Days 7 and 8 followed by P4 device removal, 400 IU eCG and 1 mg ECP on Day 8. Daily ultrasound examinations revealed that although the interval from P4 device removal to ovulation was not affected by treatment, cows that received EB + GnRH had an earlier (P < 0.05) emergence of the new follicular wave (Day 2.6 ± 0.2) than the other two treatment groups (Days 3.5 ± 0.3 and 6.1 ± 0.3, for EB and EB + P4, respectively). In Experiment 2, 808 lactating cows were assigned randomly to the three treatments evaluated in Experiment 1, and all the cows were TAI to determine P/AI. Cows in the EB + GnRH group had greater P/AI (57.4 %, P < 0.01) than those in the EB (44.6 %) or EB + P4 (45.7 %) groups. In conclusion, the administration of GnRH, but not iP4, on the day of insertion of a P4 device improves P/AI in lactating dairy cows synchronized for TAI with an estradiol/P4-based protocol.

Prostaglandin F2α treatment does not hasten ovulation in weaned sows.

This study evaluated the efficiency of prostaglandin F2α (PGF) to hasten ovulation in weaned sows. In experiment I, weaned sows detected in estrus (0 h) received: no hormone (Control; n = 56); 0.5 mg PGF IM at 0 h and 2 h (PGF0; n = 56); or 0.5 mg PGF IM at 24 h and 26 h (PGF24; n = 55). In experiment II, weaned sows that did not express estrus signs until 72 h after weaning (0 h) were assigned to: no hormone (Control; n = 45); 10 µg buserelin acetate IM at 0 h (Buserelin; n = 43); 0.5 mg PGF IM at 34 h and 36 h (PGF; n = 44); or 10 µg buserelin acetate IM at 0 h plus 0.5 mg PGF IM at 34 h and 36 h (Buserelin + PGF; n = 45). In experiment I, no effect of PGF on the interval treatment onset to ovulation was observed (P > 0.05), and no treatment effect was observed on the relative or cumulative proportion of females that ovulated post-treatment onset (P > 0.05). In experiment II, treatment onset to ovulation interval was shorter for Buserelin group than for PGF group (P < 0.05), and a higher cumulative percentage of Buserelin treated sows ovulated up to 48 h compared to PGF and Control groups (P < 0.01), with no differences from Buserelin + PGF. Treatments did not affect total number of piglets born in both experiments (P > 0.05). In conclusion, PGF did not hasten ovulation timing or affect litter size in weaned sows.

Optimizing ReBreed21 I: Evaluation of endocrine and ovarian dynamics in non-bred Bos indicus heifers.

The present study evaluated follicular and endocrine dynamics during ReBreed21, a reproductive strategy that allows resynchronization of ovulation every 21 days in Bos indicus (Nelore) heifers. A synchronized estrous cycle was induced using a standard timed ovulation protocol (d -10: P4 implant inserted + 2 mg estradiol benzoate; d -2: P4 removed+ 0.5 mg cloprostenol + 0.6 mg estradiol cypionate + 200 IU equine chorionic gonadotropin (eCG); d0: 8.4 µg buserelin) without AI to ensure nonpregnancy in heifers. Day of GnRH was designated d0 of estrous cycle. On d12, heifers (n = 80) were randomized into three experimental groups: (1) ReBreed21 (n = 28) d12 P4 device inserted, d19 P4 device withdrawal plus 200 IU eCG, and d21 8.4 µg buserelin (GnRH); (2) ReBreed21+G (n = 26) same as ReBreed21 plus GnRH (16.8 µg) treatment on d12; and (3) Control (n = 26) no treatment. ReBreed21+G increased two-fold (62.9%; 18/26) percentage of heifers with synchronized follicular wave emergence compared to Control (34.6%; 9/26) whereas ReBreed21 (53.6%; 15/28) was intermediate. The ReBreeed21 groups (eCG on d19) increased (P < 0.01) follicular growth between d19 and d21 in ReBreed21 (2.3 ± 0.2 mm) and ReBreed21+G (3.4 ± 0.2 mm) compared with Control (1.2 ± 0.3 mm), resulting in greater (P < 0.01) follicle diameter on d21 for ReBreed21 (10.7 ± 0.4 mm) and ReBreed21+G (10.8 ± 0.4 mm) compared with Control (9.1 ± 0.5 mm). Structural luteolysis was similar among groups (P = 0.51), although the average day when P4 was <1 ng/mL was later (P < 0.01) for ReBreed21 (20.5 ± 0.2) and ReBreed21+G (20.7 ± 0.2) compared to Control (19.2 ± 0.4). Overall ovulation at the end of the estrous cycle was increased (P = 0.03) for ReBreed21 groups (83.3%; 45/54) compared with Control (57.7%; 15/26). Synchronized ovulation on day 22-23 was greater (P < 0.01) for ReBreed21 (78.6%; 22/28) and ReBreed21+G (76.9%; 20/26) compared with Control (30.8%; 8/26). Thus, the ReBreed21 resynchronization program produced acceptable endocrine and follicular dynamics, including synchronized ovulation at the end of the protocol in nonpregnant heifers providing good rationale for testing the fertility and practical implementation of this protocol under field conditions.

GnRH analogue triptorelin acetate induces ovulation in jennies during oestrus.

Most of the northern hemisphere donkey breeds are faced with the risk of extinction, thus donkey reproduction is considered an emerging branch of theriogenology, and the management of artificial insemination and induction of ovulation is a crucial point in setting up preservation protocols. For four consecutive cycles, six jennies' ovarian activity was routinely monitored; an ultrasound examination was performed daily from the evidence of a follicle diameter ≥27 mm until ovulation. Upon reaching a follicular diameter ≥32 ± 2 mm (Hour 0), oestrous jennies were treated alternatively with 0.1 mg triptorelin acetate, sc, (TRIP), 0.4 mg/sc of buserelin acetate (BUS) or saline, sc, (CTRL) and examined ultrasonographically at Hours 14, 24, 38, 42, 48, 62 and every 24 h until ovulation. Induction of ovulation was considered successful if ovulation occurred from 24 to 48 h after treatment. 11/12 cycles resulted in ovulation for TRIP and 12/12 for BUS and CTRL groups, respectively. Mean ± SD ovulation time after treatment was 37.3 ± 8.3, 47.1 ± 21.0 and 66.8 ± 25.9 h for BUS, TRIP and CTRL, respectively (p = .0032). Ovulation rates between h24 and h48 were 10/12 (83.3%) for both TRIP/BUS and 2/12 (16.7%) for CTRL, respectively (p = .003). Buserelin and triptorelin-treated jennies had a 25 times higher probability to ovulate between Hours 24 and 48 than controls (p = .003), while there were no jenny and cycle effects on the ovulatory rate. The results of this study show how triptorelin successfully induced ovulation in jennies, like other GnRH analogues previously evaluated.

GnRH analogs induce a LH peak and increase pregnancy per timed-AI in ewes.

To date, there have been no studies testing the capacity of GnRH analogs and respective doses to induce a LH peak in sheep. In this sense, the present study aimed to evaluate the capacity of different synthetic forms and doses of GnRH in inducing LH release in sheep, and the effect of GnRH administration at timed artificial insemination (TAI) on pregnancy per timed-AI. In experiment 1, ewes (n = 40) received an intravaginal device (IVD) of medroxyprogesterone acetate (MPA; 60 mg) for 7 d and prostaglandin F2α analog on Day 5. On Day 7, the ewes were allocated randomly into one of eight groups (n = 5/group), which received a GnRH analog at a specific dose, as follows: lecirelin (12.5 or 25 µg), gonadorelin (50 or 100 µg), buserelin acetate (4.2 or 8.4 µg), or deslorelin (375 or 750 µg). Blood samples for LH determination were obtained at 0, 2, 4, and 6 h after GnRH and the IVDs were removed after the last blood collection. The maximal LH concentration induced by gonadorelin at doses of 50 µg and 100 µg (12.0 ± 2.4 ng/mL and 28.6 ± 7.1 ng/mL, respectively) was lower (P < 0.05) than serum LH induced by 8.4 µg of buserelin (78.9 ± 12.9 ng/mL), 375 µg and 750 µg of deslorelin (75.6 ± 7.4 ng/mL and 72.1 ± 10.6 ng/mL, respectively) and 12.5 µg and 25 µg of lecirelin (73.3 ± 17.8 ng/mL and 61.6 ± 5.9 ng/mL, respectively). However, the maximal LH concentration induced by 4.2 µg of buserelin (49.4 ± 5.9 ng/mL) was similar (P > 0.05) to the 100 µg of gonadorelin. The total release of LH (area under the curve - AUC) after treatment with 50 µg of gonadorelin (31.7 ± 5.9 ng h/mL) was lower (P < 0.05) than after other agonists. In a second experiment, 330 ewes were treated with IVD containing MPA for 7 d. Simultaneously with IVD removal, 250 µg of cloprostenol and 200 IU of eCG were administered. Then, ewes were assigned randomly to either no further treatment (control); or to receive 4.2 µg of buserelin acetate (GnRH group) at cervical TAI, which was performed with fresh semen 54 h after IVD withdrawal in all the animals. Higher pregnancy per timed-AI was observed for GnRH (50.3 %) compared to control (40.7 %). We conclude that buserelin acetate (8.4 µg), lecirelin (12.5 and 25 µg) and deslorelin (375 and 750 µg) induced a greater stimulatory effect on LH secretion than gonadorelin treatment. Furthermore, buserelin acetate treatment at TAI increased pregnancy per timed-AI in ewes previously treated with MPA and eCG.

Induced reproduction of yellow-tailed lambari (Astyanax lacustris) with Ovopel® and buserelin acetate as alternatives to the protocol with carp pituitary extract.

The objective of this study was to evaluate reproductive traits in adults of Astyanax lacustris subjected to different spawning inducers. The study involved 240 females (12.54 g ± 2.33 and 7.66 cm ± 0.63 cm) and 240 males (5.83 g ± 0.39 g and 6.14 cm ± 0.64 cm), all at reproductive age. Three different inducers were evaluated: (i) 0.4 pellets of Ovopel®/kg of body weight; (ii) 0.5 ml of buserelin acetate/kg of body weight; and (iii) carp pituitary extract (CPE) (5.5 mg CPE/kg body weight for females and 2.5 mg CPE/kg body weight for males), as well as saline solution (without hormone). The degree-hours for spawning were greater (P<0.05) for the Ovopel® treatment (with 204.93) than in the treatment with CPE (183.2). Ovary weight and gonadosomatic index were higher (P<0.05) in CPE and Ovopel® treatments when compared to buserelin acetate. The number of oocytes per female, absolute and relative fecundity were greater (P<0.05) for Ovopel® and CPE treatments. Fertilization rate was higher (P<0.05) in treatment with buserelin acetate (82.3%) in relation to Ovopel® (72.33%) and CPE (62.40%) treatments, and the highest (P<0.05) hatching rates were achieved with buserelin acetate and Ovopel®. The number of larvae per female body weight was greater (P<0.05) when Ovopel® was used. In conclusion, Ovopel® proves to be a more effective reproductive inducer for induced reproduction of A. lacustris when compared to CPE and buserelin acetate.

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 repeated low doses of GnRH analogue (buserelin) on fertility performance of dairy cows with anovulation type I.

The aim of this study was to evaluate the fertility response of dairy cows with anovulation type I on repeated low doses of GnRH agonist buserelin. The study was conducted on 83 anovulatory and 60 cyclic Polish Holstein Friesian cows. Anovulation type I was defined as small ovaries with follicles of ≤ 5 mm in diameter and without corpus luteum on two examinations in a 7-10 day interval between 50-60 days after parturition. Cows from the experimental group (n=58) received 0.4 µg of buserelin i.m. once a day for 5 consecutive days. Cows from the negative control group (n = 25) received saline. Sixty cyclic cows receiving no treatment served as positive controls. Intervals from calving to estrus and from calving to conception, pregnancy rate 30-35 days and 260 days after AI, and pregnancy loss were calculated. The anovulatory cows had a substantially prolonged calving to conception interval, decreased pregnancy rate and increased pregnancy loss and culling rate compared to cyclic herd mates. The average calving to conception interval was significantly (p⟨0.05) shorter in treated cows compared to non-treated anovulatory cows (153.7 days vs 209.3 days). In conclusion, repeated low doses of GnRH analogue buserelin led to a significant shortening of calving to conception interval. More clinical trials are needed to determine the practical usefulness of this method for the treatment of anovulation type I in dairy cows.

Effect of increased serum progesterone on luteal morphology and function, pregnancy, and gestational loss in Nelore cows.

The aim of the present study was to determine the impact of different strategies for increasing the level of serum progesterone (P4) on luteal morphology and function in bovine females. The effects of increasing P4 on pregnancy rate and gestational loss (GL) in Nelore cows subjected to timed artificial insemination (TAI) were also evaluated. A total of 939 cows were divided into three groups: P4LA (n = 305), 150 mg of long-acting injectable P4 7 days after TAI; GnRH (n = 306), 10 µg of buserelin acetate 7 days after TAI; and control (n = 328), no hormone treatment after TAI. Doppler ultrasound assessments and P4 measurements were performed on days 7 and 16 after TAI. The pregnancy rate and GL as a function of treatment were compared using the SAS GLIMMIX procedure. Corpus luteum (CL) vascular perfusion, volume, and plasma P4 concentration were analysed using the SAS PROC MIXED procedure. No significant difference was found among the treatments in terms of volume, number of pixels, and CL intensity or in the serum P4 concentration at 7 days after ovulation. The CL blood flow at 16 days after ovulation was lower in the P4LA and GnRH groups than that in the control group (p < .01). Serum concentrations of P4 at 16 days after ovulation were higher in the P4LA and GnRH groups than those in the control group (p = .04). A difference in the pregnancy rate (p = .003) and a trend in GL (p = .07) as a function of treatment were found. Overall, long-acting injectable P4 supplementation on day 7 after TAI or GnRH administration affected CL vascularization and increased the serum concentrations of P4 16 days after ovulation, promoting better pregnancy rates than the control.

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) 7 days prior to Ovsynch in Hariana cow. Two hundred cyclic cows (> 4 months postpartum) were assigned to control (n = 54) and pre-OV (n = 146). As per Ovsynch protocol, buserelin acetate (10 µg), cloprostenol (500 µg), and buserelin acetate (10 µg) were injected i.m. on days 0, 7, and 9, respectively, in cows irrespective of treatment. But in pre-OV cows, buserelin acetate (10 µg) and cloprostenol (500 µg) were also injected i.m. simultaneously 7 days prior to initiate the Ovsynch protocol. Artificial insemination was performed between 18 and 24 h 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 12 days 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 7 days 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.

Effect of repeated low doses of GnRH on follicular development and ovulation in anovulatory dairy cows with follicle growth to emergence size.

The aim of the study was to evaluate the effect of repeated low doses of GnRH agonist buserelin once a day for 5 days on follicle development and ovulation in anovulatory dairy cows with follicles growth only to emergence. The study was conducted on 71 anovulatory Polish Holstein Friesian cows. Anovulation with growth of follicles to emergence was defined as small ovaries with follicles of ≤ 5 mm in diameter and without corpus luteum on two examinations in a 7-10 day interval between 50-60 days after parturition. Cows were allocated to one of two group. Cows from group 1 (n = 58) received 0.4 µg of buserelin (Receptal, MSD, Poland) i.m. once a day for 5 days. Control cows from group 2 (n = 13) received saline. Ovarian structures were monitored weekly after the end of treatment by ultrasound for 4 weeks. The diameter of ovarian follicles on the ovaries was measured and recorded. Occurrence of ovulation was determined by the presence of corpus luteum. Overall, ovulation occurred in 46.6% (27/58) of cows treated with repeated doses of GnRH, while no corpus luteum was observed in the control group during the study period. There were significantly (p⟨0.05) more follicles 6-9 mm in diameter and 10-20 mm in diameter in cows treated with GnRH than in control cows. In conclusion, repeated low doses of GnRH analogue buserelin once a day for 5 days stimulate the development of ovarian follicles in anovulatory dairy cows with small ovarian follicles and led to ovulation in 46.6% of cows during 4 weeks after the end of the treatment.

Mitigation of low pregnancy rate in excitable Nellore cows by administration of GnRH or P4.

This research aimed to determine the effect of temperament on reproductive parameters including cortisol and progesterone (P4) in Nellore cows. Additionally, two methods for increasing plasma progesterone (P4) levels in excitable animals to enhance pregnancy rate (P/AI) and reduce pregnancy loss were investigated. In total, 939 cows were subjected to timed artificial insemination (TAI) and divided into three groups: (P4LA; n = 305) 150 mg of injectable long-acting progestogen 7 days after TAI; (GnRH; n = 306), 10 µg of buserelin acetate on day 7 after TAI; control group (CG; n = 328) without hormonal treatment. In 213 cows, randomly chosen from each group, ultrasound evaluations of the preovulatory follicle (Mode B) were performed on the day of insemination and of the corpus luteum (Color Doppler) 7 and 16 days after TAI. Blood samples were obtained from 20% of the 939 animals, randomly chosen from each group, on the day of insemination and after 7 and 16 days to measure cortisol and progesterone, respectively. At the time of insemination, subjective temperament evaluations were performed with the animals being classified as excitable (EXC) or adequate (ADQ). The SAS GLIMMIX procedure was used to compare the pregnancy rate (P/AI) and gestational loss within each temperament for the three experimental groups. Continuous variables were analyzed utilizing SAS PROC MIXED procedure. Cortisol concentration was higher and POF (preovulatory follicle) and CL (corpus luteum) volumes at the time of insemination and 7 days after AI, respectively, were lower in EXC animals than in ADQ. No significant difference was observed between the number of pixels, CL intensity, and plasma concentration of P4, 7 days after TAI. However, 16 days post-insemination, among the animals classified as EXC, higher concentrations of P4 were observed in the GnRH and P4LA groups than in the control. Regarding P4 concentrations, there was a tendency to be lower in animals classified as EXC than in ADQ within the control group (P = 0.06), while rate of blood flow from the CL was lower in EXC animals than in ADQ animals (P = 0.04). Among the ADQ animals, the GnRH and P4LA groups showed a lower CL flow rate than that observed in the control (P = 0.04), 16 days after the TAI. Among EXC animals, a higher pregnancy rate was observed in the GnRH and P4LA groups than in the control group (P = 0.01). In the control group, the pregnancy rate (P/AI) of the ADQ animals was higher than that of the EXC animals (P = 0.05). No statistically significant differences were observed between gestational losses when the treatments or temperaments were compared. In conclusion, the use of GnRH or P4LA, 7 days after insemination, improves pregnancy rates in excitable animals and is a viable alternative to minimize the negative impact of stress and improve reproductive efficiency in beef cattle.

The Kisspeptin analogue C6 induces ovulation in jennies.

Kisspeptins (KPs) are the most potent stimulating neurotransmitters of GnRH release, and consequently KP administration triggers LH and/or FSH release. In small ruminants, KP or its analogs induced an LH surge followed by ovulation in both cyclic and acyclic animals, while in the mare KP only increased LH plasma levels but failed to induce ovulation. This study in jennies compares the endocrinological effects, ovulatory and pregnancy rates of the KP analog C6 and the GnRH analog buserelin acetate. The ovarian activity of nine Amiata jennies was monitored daily by transrectal ultrasound for three complete estrous cycles. Jennies in estrus were assigned, to one of three treatment groups: 50 nmol of the KP analog C6 (injected twice, 24 h apart, C6 group); 0.4 mg buserelin acetate (injected once, Bu group); and 2 mL of saline (injected once, CTRL group). Blood samples were collected at Day-1 (-24 h) Day0 (h0, before treatment), h2, h4, h6, h8, h10, h24 (before second treatment with C6), h26, h28, h30, h32, h34, h48 and every 24 h until ovulation. Jennies were inseminated once at h24 with fresh extended semen from a donkey stallion. Pregnancy diagnoses were performed 14 days after ovulation. On days 5, 10, and 14 after ovulation, for every CL the cross-sectional area (CSA) and the vascularized area (VA) were recorded by color doppler ultrasound and measured. Significantly higher plasma LH levels were found after induction between the Bu and CTRL groups at h6 and h8 (P < 0.05), while tendentially higher differences were found between the Bu/C6 groups and CTRL at h10. Five/9, 4/9, and 2/9 jennies ovulated between 24 and 48 h after induction from the Bu, C6, and CTRL groups respectively, (P > 0.05). Correlations between corpora lutea CSA and VA with serum progesterone concentration were r = 0.31, P = 0.01, r = 0.38, P = 0.01, respectively. Pregnancy rates after artificial insemination did not differ among groups (CTRL: 6/9, 66.7%; C6: 7/9, 77.8%; Bu: 6/9, 66.7%; P > 0.05). Ovulation rates after C6 treatment were comparable to that of Bu, although not different from the CTRL. Pregnancy rates were comparable to the literature in terms of fresh extended donkey semen in every group. This study suggests that stimulation of the Kp system in jennies, in contrast to findings observed in mares, induces ovulation. Further studies using higher doses and/or more animals are needed to better characterize the efficacy of C6 in jennies.

LH pattern and ovarian response in ovsynch-synchronized superovulated goats induced to ovulate with GnRH or hCG.

The intention of the present investigation was to compare a GnRH agonist and hCG as ovulation inducing agents to apply fixed-time insemination in ovsynch synchronized superovulated goats. Three groups of 17 does of the Boer goat breed were synchronized, superovulated and ovulation induced with a GnRH analog, hCG or physiological saline, followed by mating and non-surgical embryo collection. Part of the does were provided with subcutaneous progesterone implants after mating to compensate for frequently occurring premature corpus luteum regression. Estrus detection was conducted with aproned bucks, ovarian function was monitored sonographically and by progesterone analyses and blood samples were drawn to generate LH profiles. Practically all does responded to treatment and occurrence and duration of estrus as well as the ovulatory response were unaffected by treatment. The LH surge provoked by administration of the GnRH analog buserelin emerged within 1.0 h and was closely synchronized, significantly more so than after administration of hCG or physiological saline, commencing after 11.8 and 14.9 h, respectively, with no significant differences amongst each other. It would seem that hCG is not effective in bringing about a LH surge. The interval between commencement of the LH surge and ovulation was, across treatment groups, 24.2 h with no significant difference among groups. Ovulatory response and yield of transferable embryos obtained by nonsurgical collection were modest with no significant differences among groups.

hCG is more effective than the GnRH agonist buserelin for inducing the first ovulation of the breeding season in mares.

BACKGROUND: Human Chorionic Gonadotropin (hCG) and Gonadotropin Releasing Hormone agonists (GnRHa) are routinely used to induce ovulation in mares. However, GnRHa efficacy in transitional mares has been suggested to be low. OBJECTIVES: The aims of this study were as follows: (a) to compare the efficacy of hCG and GnRHa in inducing the first ovulation of the breeding season and (b) to evaluate the correlation between ovulatory response, uterine oedema and teasing score at the time of treatment during the early or late transitional phase. STUDY DESIGN: Randomised controlled superiority trial. METHODS: Mares in winter anoestrus were treated with sulpiride when at least two follicles reached a diameter of 25 mm. The day after the follicle reached 35 mm in diameter, mares in oestrus were treated with GnRHa buserelin (N = 29) or hCG (N = 33) and checked daily for ovulation. RESULTS: More mares (30/33, 90.1%) ovulated when the first ovulation after winter anoestrus was induced with hCG, than with GnRHa, (11/29, 38.0%) (P = .0001). Ovulation rate was lower in mares that did not show uterine oedema and full acceptance of the teaser stallion for at least three days before the treatment (32/41, 78% vs 9/21, 42.9%) P = .01. MAIN LIMITATIONS: Plasma LH and oestrogen concentrations were not performed. CONCLUSIONS: These results demonstrate that hCG was more effective than GnRHa for inducing ovulation in the first cycle after winter anoestrus. Uterine oedema and behavioural signs of oestrus, for at least three days before the treatment, were predictors for a positive response to ovulation induction.

Effects of buserelin administration on testicular blood flow and plasma concentrations of testosterone and estradiol-17ß in rams.

This research aimed to examine for the first time the impact of single dose administration of gonadotropin-releasing hormone (GnRH) analog buserelin acetate on the testicular blood flow measurements (peak systolic velocity [PSV], end-diastolic systolic velocity [EDV], resistive index [RI], and pulsatility index [PI]) and the plasma steroids (testosterone and estradiol-17ß) concentrations in rams. For this purpose, twelve adult Ossimi rams were randomly assigned into the buserelin group (n = 8) and were injected intravenously (iv) with buserelin acetate (0.008 mg/ram), whereas the remaining rams (n = 4) were injected with normal saline iv and served as a control group. Blood sampling and testicular pulsed-wave Doppler scanning were conducted immediately before (0) and 1, 3, 6, 24, 48, 72, 120, and 168 h after treatment. The control group did not reveal any substantial changes (P > 0.05) in the examined parameters, except for the EDV (P < 0.05). In the buserelin-treated group, a marked reduction in RI and PI values (P < 0.05) occurred 1 to 3 h after administration of buserelin. Besides, there was a significant increase in testosterone plasma concentrations following buserelin treatment. In conclusion, the administration of buserelin triggered a series of substantial changes in the testicular blood perfusion and steroidogenesis that could have a positive effect on testicular function in rams.

The effect of glutathione and buserelin on the stereological parameters of the hypothalamus in the cyclophosphamide-treated mice.

INTRODUCTION: New anticancer drugs have increased the survival and fertility rates in young patients. These drugs (i.e., cyclophosphamide; Cyc) have some side effects on the hypothalamus and fertility. One possible chemical for reducing these side effects is thiol or GnRH agonist. This study aimed to evaluate the capability of these agents for reducing the cyclophosphamide effects on the hypothalamus. METHODS: Sixty-three female mice were randomly assigned into seven groups. All groups including the control group had free access to water and mouse chow ad libitum. The sham group received normal saline. The Glu and Bus groups received glutathione (Glu) and buserelin (Bus) daily for 16 days, while the Cyc group received only cyclophosphamide as a single dose; the Cyc + Glu and Cyc + Bus groups, in addition to cyclophosphamide, received glutathione and buserelin, respectively. The volume of the hypothalamus, its neuron number, and dead neurons were evaluated using stereological methods. RESULTS: There was no significant difference in the evaluated stereological parameters between the control and sham groups. However, the animals which received Cyc showed a decrease in the volume of the hypothalamus and its neuron number and density and an increase in cell death as compared with the control group. The treatment of the mice that received Cyc with Glu or Bus prevented these changes. CONCLUSION: This study showed that both GnRH agonist and thiol preserved or improved structural changes in the hypothalamus caused by cyclophosphamide in mice, suggesting that using thiol and especially GnRH agonist along with chemotherapy drugs may have protective effects on fertility.

Tambaqui females (Colossoma macropomum) spawn after hormonal induction with buserelin acetate.

The aim of this study was to evaluate induced reproduction in tambaqui females using buserelin acetate as compared with the traditional treatment regimen with carp pituitary extract (CPE). Reproductive traits of females with a body weight (BW) of 8.47 ±â€¯1.52 kg were evaluated in ten females treated with buserelin acetate at the dose of 0.5 mL/kg BW, in a single application, and in ten females treated with CPE at the dose of 5.5 mg/kg BW, in two applications (10 % and 90 %, with a 12-h interval between applications). Spawning rate did not differ between the females treated with buserelin acetate (40 %) and CPE (40 %). Weight, fertilization rate and hatching rate did not differ between the two treatment groups. Degree-hours (determined as the average temperature multiplied by time, in hours, for spawning after the treatment with the second dose of CPE and after the single treatment with buserelin acetate) for spawning and number of oocytes per gram of gametes collected were greater (P < 0.05) in the females treated with buserelin acetate than in the females treated with CPE. Production index, absolute fecundity and relative fecundity were greater (P < 0.05) in the females treated with CPE. The hormone buserelin acetate promotes reproduction in tambaqui females with there being a similar spawning rate and oocyte quality, however, lesser production indices and fecundity than when there is the conventional treatment regimen imposed with carp pituitary extract.

Progesterone-based timed AI protocols for Bos indicus cattle II: Reproductive outcomes of either EB or GnRH-type protocol, using or not GnRH at AI.

The aim of these experiments was to study ovarian dynamics and fertility of Bos indicus beef cattle submitted to 7-d progesterone (P4)-based fixed-time AI (FTAI) protocols using different hormonal treatments. In Exp. 1, 2 yr old Nelore heifers (n = 973) were randomly assigned to one of four treatments: EB-0 (estradiol benzoate, EB on D0 and no GnRH at AI), EB-G (EB on D0 and GnRH at AI), G-0 (GnRH on D0 and no GnRH at AI), or G-G (GnRH on D0 and at AI). On D0, heifers received an intravaginal P4 implant (0.5 g) for 7 d and EB (1.5 mg) or GnRH (16.8 µg). On D7, the P4 implant was withdrawn and heifers received cloprostenol (PGF; 0.5 mg) and estradiol cypionate (EC, 0.5 mg). Heifers in G groups also received PGF and eCG (200 IU) on D6, whereas EB heifers received eCG on D7. At FTAI on D9, only EB-G and G-G groups received GnRH (8.4 µg). In Exp. 2, Nelore cows (n = 804) received the same treatments (EB-0, EB-G, G-0, or G-G) using a 1.0 g P4 implant, 2.0 mg EB, and 300 IU eCG. Effects were considered significant when P ≤ 0.05. After treatment on D0, G had more ovulations than EB in heifers (60.3 [287/476] vs. 12.7% [63/497]) and cows (73.7 [83/112] vs. 24.4% [28/113]). Luteolysis after D0 was greater in EB than G in heifers (39.2 [159/406] vs. 20.0% [77/385]) and cows (25.5 [14/55] vs. 1.6% [1/64]). Heifers in G had larger follicles (mm) than EB on D7 (10.3 ± 0.2 vs. 9.2 ± 0.2) and at AI (11.9 ± 0.2 vs. 11.3 ± 0.2). Cows had larger follicles in G than EB on D7 (11.0 ± 0.3 vs. 9.9 ± 0.3) but not at AI. More estrus was observed in G than EB for heifers (80.3 [382/476] vs. 69.6% [346/497]) and cows (67.6 [270/400] vs. 56.2% [227/404]). There was no interaction between D0 and D9 treatments on pregnancy per AI (P/AI) in heifers (EB-0: 56.7 [139/245], EB-G: 53.6 [135/252], G-0: 52.6 [127/241], and G-G: 57.5% [135/235]). However, cows from EB-G had greater P/AI than EB-0 (69.5 [142/204] vs. 60.2% [120/200]), whereas P/AI for G-0 (62.7% [127/203]) was similar to G-G (60.9% [120/197]). In heifers, there was no interaction of GnRH at AI with estrus, however, cows that did not display estrus had greater P/AI if they received GnRH at AI (GnRH = 59.1 [91/154] vs. No GnRH = 48.2% [78/162]). Thus, protocols initiated with EB or GnRH for Bos indicus heifers and cows had differing ovarian dynamics but similar overall fertility, enabling their use in reproductive management programs. Treatment with GnRH at time of AI increased fertility in some instances in Bos indicus cows but not in heifers.

Single injection of triptorelin or buserelin acetate in saline solution induces ovulation in mares the same as a single injection of hCG.

The aim of this study was to assess the efficacy of different doses of buserelin acetate and another GnRH agonist, triptorelin acetate, in saline solution in a single subcutaneous injection, to induce ovulation of growing pre-ovulatory follicle in mare and compare it with the classical treatment of a single injection of hCG. The study is split into 3 experiments over different breeding seasons in the same stud with a random distribution of treatment. The first one was to compare the injection of 6 mg of buserelin with 1,500 IU of hCG; the second one consisted of comparing different doses of buserelin (6 mg and 3 mg); and the third one compared three different doses of buserelin (3, 2 and 1 mg), 0.1 mg of triptorelin with 1,500 IU of hCG as a control group. The results of all experiments showed the same efficacy between all treatments with mares ovulating between 24 and 48 hr after injection: experiment 1: hCG (78% n = 41) and buserelin 6 mg (90% n = 50); experiment 2: buserelin 6 mg (78,1% n = 192) and buserelin 3 mg (78% n = 341); and experiment 3: hCG (87% n = 106), buserelin 3 mg (84,7% n = 137), buserelin 2 mg (82,7% n = 104), buserelin 1 mg (87% n = 54) and triptorelin 0.1 mg (84,7% n = 72). In conclusion, this study contributes to erasing the dogma that has been established since 1975 that a single injection in solution without any long-acting excipient of a GnRH agonist cannot induce ovulation in the mare. This study also shows that a injection of 0.1 mg of triptorelin in solution is a good alternative for ovulation induction and is comparable to small doses of buserelin acetate in solution (1 mg) and 1,500 IU of the gold standard trigger hCG, mainly in countries where human formulation of buserelin is not available.