Haemorrhage into the dominant follicle during the reproductive season is a subtle but definitive cause of infertility in the mare population. This condition however can be of high relevance for an individual in which its incidence is abnormally high. Little is known about the nature and factors affecting the incidence of haemorrhagic anovulatory follicles (HAFs) in the mare. The objectives of the study were to define and characterize the ultrasonographic development and incidence of HAFs and to investigate possible risk factors influencing its occurrence. Detailed reproductive and ultrasound records of seven mares studied during their entire reproductive lives (>10 years and 612 oestrous cycles) were analysed retrospectively and computed into a statistical mixed model. Of all animal studied, two mares were found to have an unusually high incidence of HAFs of approximately 25%. Time of season and use of induction treatments (Cloprostenol) were found to influence its incidence. It appears that early-enhanced stimulatory effect of LH on an ovary with the presence of small and immature follicles might increase the risk of ovulatory failure of those follicles later in the cycle. Mares during the months of highest follicular activity (May to August) and after treatment with hormones to induce oestrus and ovulation are at greater risk to develop HAFs. The potential relevance of this study is two folds: clinical relevance for the practitioner to better understand this condition and so improve reproductive management of mares with abnormally high incidence; and to provide useful insights for researchers willing to further investigate the nature of this phenomenon.

Heifers (n=31) were superovulated with an FSH-P/cloprostenol regimen, and at 12 and 24 hours after the onset of estrus they were inseminated. Blood sampling for LH analyses and ultrasound scanning of the ovaries were performed at 4-hours intervals. The scanning, at which the first and last ovulations were recorded, was performed at 22.7 +/- 1.5 (mean +/- SD) and 31.0 +/- 1.5 hours after the LH peak, respectively. An average of 7.8 +/- 1.0 ovulations was monitored when the first ovulations were detected, while 2.8 +/- 0.7 ovulations occurred later. At 16 hours after detection of the first ovulations the oviducts were flushed and 5.6 +/- 0.5 fertilized and 2.3 +/- 0.3 unfertilized ova were isolated per animal. The fertilized ova displayed spherical pronuclei of synchronous development, and polyspermic penetration was not seen. At 24 hours after detection of the first ovulations the content of the remaining 3.3 +/- 0.5 nonovulatory follicles>> 8 mm per animal was aspirated. Expanded cumulus investment was found in 69.4% of the oocytes, while 22.4% had abstricted the first polar body.

The objectives of this study were to evaluate the efficacy of (1) administering ceftiofur hydrochloride in dairy cows with calving-related disorders to prevent metritis and (2) a combination of GnRH and PGF2α for the treatment of clinical endometritis, under Argentinean dairy farming conditions. Cows at high risk (HRC) for metritis (dystocia, RFM >12 h postpartum, hypocalcaemia, twins, or stillbirth) were randomly assigned to receive either 1.1 mg/Kg of ceftiofur hydrochloride on three consecutive days (HRC treated group HRCT, n = 110) or remained untreated (HRC control group HRCC, n = 126). Cows with low risk (LRC, no calving-related disorders, n = 868) did not receive any treatment (LRC group, n = 868). All cows were examined for metritis between days 4 and 10 and for clinical endometritis between 24 and 30 days postpartum. The body condition score (BCS) was recorded at both examinations. Cows with endometritis at days 24 to 30 postpartum received either 1.5 mg of D-cloprostenol (PGF; n = 129) or 100 μg of GnRH followed by D-cloprostenol after 7 days (GnRH+PGF, n = 119). There was no overall effect of treatment on the incidence of metritis or on time to pregnancy. Treatment, however, reduced the incidence of metritis in cows with high BCS (HRCT = 24.0 %, HRCC = 38.5 %) but had no effect in cows with low BCS (HRCT = 38.7 %, HRCC = 37.5 %). The proportion of pregnant cows by days in milk was greater (P < 0.01) in LRC group compared with that of the HRCT and HRCC groups. No significant differences were found between groups PG and PG+GNRH. GnRH+PGF treatment, however, tended (P = 0.06) to increase pregnancy rate in cows with a moderate loss of BCS (76.5 vs 65.2 %) but tended to reduce pregnancy rate (54.5 vs 76.0 %) in cows with a more pronounced loss in BCS (>0.75 points).

The effects of stimulation and suppression of uterine contractility at about the time of insemination on sperm distribution and fertilization in multiparous sows are described. For assessment of fertilization, sows were inseminated about 28 h before (synchronized) ovulation and killed at day 5 after ovulation (n = 53). For assessment of sperm distribution, sows were inseminated about 20 h before expected ovulation and were killed 12 h later (n = 26). At 10 min before insemination, sows received an intrauterine infusion of one of three solutions: (i) saline (control); (ii) 0.60 mg clenbuterol hydrochloride to suppress contractility; or (iii) 1 mg cloprostenol to stimulate contractility. Both clenbuterol and cloprostenol reduced median fertilization rate (P < 0.05) and median number of accessory sperm cells (P < 0.05). Distribution of sperm cells was also affected by treatments. Clenbuterol increased, and cloprostenol decreased, the number of sperm cells (P < 0.05) in the proximal 20 cm of the uterine horn and in the uterotubal junction. In addition, clenbuterol tended to increase and cloprostenol tended to decrease the number of sperm cells in the isthmus, although these effects were not significant. However, relative to the number of sperm cells in the uterus, clenbuterol treatment reduced the number of sperm cells in the uterotubal junction and oviduct, in contrast to cloprostenol. Cloprostenol increased the reflux of semen during insemination. It is hypothesized that suppression of uterine contractility increases transuterine transport time, reducing the ability of sperm cells to enter the uterotubal junction and the oviduct. Stimulation of uterine contractility above a certain level probably increases reflux and impedes transuterine transport of sufficient numbers of sperm cells.

The present study was carried out to investigate the efficiency of superovulation, oestrus synchronization, and embryo recovery in Tianzhu white yaks and also to confirm the pregnancy rate of black yaks, to which embryos collected from white yaks were transplanted. Forty-seven yaks were selected from different experiment groups, including 10 Tianzhu white female yaks (donor, group A) and 37 black female yaks (recipient, groups B and C). Superovulation of the donor was induced by the application procedure of CIDR-B+FSH+PG. Oestrus synchronization of recipients was induced using two methods: group B was given the same treatment as group A, except that the follicle-stimulating hormone (FSH) injection was not administered, whereas group C was injected with cloprostenol only once when corpus luteum (corpora lutea) was (were) palpated. The results showed that the oestrous rates in group A were higher (80%) than those in group B (60%) and group C (44.5%). As for the efficiency of superovulation, it was indicated that the mean numbers (+/-SD) of total corpora lutea, follicles, viable (transferable), and degenerated embryos were 4.75+/-2.19, 1.13+/-0.83, 2.50+/-1.31, and 1.38+/-0.92, respectively. The mean embryo recovery rates were 55.6%. All together, 18 viable embryos of Tianzhu white yak were obtained and 12 of them were transplanted to 10 recipients. The pregnancy rate was 50% and the delivery rate was 40%.

Lactating, nonpregnant (with a corpus luteum) Holsteins were given 100 ug GnRH (n = 12) or saline (n = 12) and 500 ug cloprostenol 6 d later. Following luteolysis, ovulation occurred 10.1 +/- 0.2 d (range, 9-12 d) after GnRH and 8.6 +/- 1.0 d (range, 3-12 d) after saline (differences between groups: means, P>> 0.05; variability, P < 0.001). Treatment with GnRH and cloprostenol resulted in a relatively synchronous ovulation.

The association between use of hormone treatments to induce estrus and ovulation and the incidence of hemorrhagic anovulatory follicles (HAFs) was studied in a mixed population of mares (Equus caballus) during two breeding seasons in a commercial breeding clinic. Mares treated with cloprostenol (CLO) were more likely to develop HAFs than were mares with spontaneous cycles (P<0.001) or those treated with human chorionic gonadotropin alone (P=0.08). There was no significant effect of season on the incidence of HAFs. The mean (+/-SEM) interval from CLO treatment to beginning of HAF development was 6.1+/-0.5 d. Age of mares with HAF cycles was not different (12+/-1.3 yr; P>0.05) from that of mares with ovulatory cycles (10.5+/-1.5 yr).

Mules, hybrids resulting from the mating of a horse mare (Equus caballus, 2n = 64) to a Jack donkey (E. asinus, 2n = 62), are generally infertile. Five horse embryos were transferred non-surgically to two cyclic and one acyclic recipient mules. In the mares and cycling mules, oestrus and ovulation were induced with, respectively, d-cloprostenol and human chorionic gonadotrophin (hCG). The acyclic mule, on the other hand, received oestradiol benzoate when the embryo donor was showing oestrus and progesterone after the donor had ovulated and until pregnancy diagnosis. Non-surgical embryo collections were attempted on day 7 after ovulation and recovered embryos were transferred transcervically into the mules' uteri. Mules that became pregnant were blood sampled serially for equine chorion gonadotrophin (eCG), progestagen and total conjugated oestrogen concentrations until around 6 months of gestation. The three embryos transferred to the acyclic mule did not produce any pregnancies whereas both embryos transferred to the cycling mules resulted in the birth of live foals. The peak concentration and duration of secretion of eCG differed markedly between the two pregnant mules, although both animals appeared to develop secondary corpora lutea beyond day 40 of gestation, as in normal intraspecies horse pregnancy. Moreover, the rise in serum oestrogen concentrations from around day 90 was also similar to that seen in normal pregnant mares. Parturition occurred spontaneously on day 348 of gestation in both mules and the resulting colt foals developed normally to weaning. Thus, cycling mules can carry a horse conceptus after non-surgical embryo transfer and give birth to a normal mature foal.

The present study aimed to compare two methods of prostaglandin-induced abortion in mares by determining blood markers (progesterone, estradiol-17β, alpha-fetoprotein, 13,14-dihydro-15-keto-prostaglandin-F2α (PGFM)), B-mode ultrasonographic parameters, and time until loss of fetal heartbeat. It was hypothesized that intrauterine infusion of cloprostenol results in earlier fetal compromise than intramuscular administration. Ovarian structures (number and sizes of follicles and corpora lutea area), fetal heartbeat, and fetal mobility of thirteen singleton pregnancies were assessed daily by transrectal ultrasonography until induction of pregnancy termination (60 ± 2 days of gestation). Mares received 500 μg of cloprostenol intramuscularly every 12 h (IM, n = 7) or once transcervically (TC, n = 6). After initial cloprostenol administration, ultrasonographic examinations were repeated at 6-h intervals until loss of fetal heartbeat was detected. Plasma progesterone, estradiol-17β, and alpha-fetoprotein were assessed for five days before and after pregnancy loss. In addition, plasma PGFM concentrations were assessed immediately before cloprostenol administration (0 min), and then 15, 30, and 45 min, and 1, 2, 3, 4, 6, 12 h after administration. Data were analyzed using the MIXED procedure with repeated measures in SAS. Significance was set at P < 0.05. All mares lost their pregnancies within 48 h after initial cloprostenol administration, with no difference in time to pregnancy loss. There were significant effects of time starting by 12 h post-induction of pregnancy termination but there was no time by group interaction for progesterone concentrations. Estradiol-17β and alpha-fetoprotein concentrations were not altered upon impending abortion. Concentrations of PGFM increased significantly by 2 h after cloprostenol administration, but there were no differences between groups. No time effects or time by group interaction for fetal mobility and heartbeat was detected. Expectedly, the number and area of corpora lutea decreased significantly after cloprostenol administration with no significant differences between groups. In conclusion, intrauterine administration of cloprostenol was not different from repeated systemic administration to terminate the pregnancy. Both models for early fetal loss were equivalent for the endpoints assessed herein. The present study provides evidence that transcervical cloprostenol administration technique is repeatable in different settings and results in negligible side effects. While systemic administration results in colic-like signs and may result in severe reaction.

This study aimed to compare the reproductive efficiency of dairy buffaloes subjected to TAI protocols based on progesterone, estrogen, and equine chorionic gonadotrophin (P4/E2+eCG) during the fall/winter (n = 168) and spring/summer (n = 183). Buffaloes received an intravaginal P4 device (1.0 g) plus estradiol benzoate (EB; 2.0 mg im) at a random stage of the estrous cycle (D-12). Nine days later (D-3), the P4 device was removed and buffaloes were given PGF2α (0.53 mg im sodium cloprostenol) plus eCG (400 IU im). GnRH (10 μg im buserelin acetate) was administered 48 h after P4 device removal (D-1). All animals were subjected to TAI 16 h after GnRH administration (D0). Frozen-thawed semen from one bull was used for all TAI, which were all performed by the same technician. Ultrasound examinations were performed on D-12 and D-3 to ascertain cyclicity (presence of CL), D-3 and D0 to measure the diameter of the dominant follicle (ØDF), D+10 to verify the ovulation rate and diameter of the corpus luteum (ØCL), and D+30 and D+45 to detect pregnancy rate (P/AI 30d and 45d, respectively) and embryonic mortality (EM). Fetal mortality (FM) was established between 45 days and birth, and pregnancy loss between 30 days and birth. There were significant differences between fall/winter and spring/summer only for cyclicity rate [76.2% (128/168) vs. 42.6% (78/183); P = 0.02]. The others variables did not differ between the seasons: ØDF on D-3 (9.6 ± 0.2 mm vs. 9.8 ± 0.2 mm; P = 0.35); ØDF on D0 (13.1 ± 0.2 mm vs. 13.2 ± 0.2 mm; P = 0.47); ovulation rate [86.9% (146/168) vs. 82.9% (152/182); P = 0.19]; ØCL on D+10 (19.0 ± 0.3 mm vs. 18.4 ± 0.3 mm, P = 0.20); P/AI on D+30 [66.7% (112/168) vs. 62.7% (111/177); P = 0.31]; P/AI on D+45 [64.8%% (107/165) vs. 60.2% (106/176); P = 0.37]; EM [1.8% (2/111) vs. 3.6% (4/110); P = 0.95]; FM [21.9% (18/82) vs. 8.0% (7/87); P = 0.13]; and PL [23.8% (20/84) vs. 12.1% (11/91); P = 0.13]. In conclusion, dairy buffaloes present similar reproductive efficiency in fall/winter and spring/summer when subjected to P4/E2/eCG-based protocol for TAI.

The Japanese black cattle breed (Wagyu) has an improved metabolism, which allows them to have a higher marbling score when compared with other cattle breeds. However, this may affect other aspects of the animal's physiology, including hormone secretion and their reproductive success, such as their response to synchronization protocols and embryo production. Therefore, the objectives of this study were to test a superovulation protocol (SOV) developed with low doses of FSH and to evaluate the outcome and economic viability of embryo production using the SOV and in vitro fertilization (IVF) approaches in the Wagyu cattle breed. For that, ten Wagyu cows were submitted to five SOVs over a period of 15 months using a standard protocol: CIDR + 3 mg estradiol benzoate (D0), 35 mg FSH (Folltropin^®) a.m. and p.m. (D4), 35 mg Folltropin^® a.m. and 20 mg p.m. (D5), 20 mg Folltropin^® a.m. and 10 mg p.m. (D6), 10 mg Folltropin^® and 0.5 mg cloprostenol, both a.m. and p.m., + CIDR removal (D7), 0.05 mg GnRH + insemination 12 and 24 h after (D8) and embryo collection + 0.5 mg of cloprostenol (D16). Thirty days after each SOV, a follicular aspiration was conducted to produce IVF embryos without any pre-synchronization using standard semen in the same group of animals. The average number of embryos produced was 7.63 ± 5.61 (SOV) and 4.52 ± 2.44 (IVF) (p = 0.303). There was no significant correlation between the number of embryos produced by the different techniques (SOV and IVF), indicating that cows that respond well to SOV did not respond well to IVF and vice versa (r = 0.379, p = 0.529). The total cost of each embryo produced by SOV was R$215.00 and R$410.00 for IVF. Therefore, cows that produce less than five embryos by SOV are not economically viable due their lack of response to FSH, and the use of IVF in those animals may be more effective.

OBJECTIVE

To examine factors associated with fertility on dairy farms that used a common fixed-time artificial insemination (FTAI) program in yearling heifers.

METHODS

Records were analysed from 954 yearling heifers on 10 south-west Victorian dairy farms that used a common FTAI program, involving the insertion of a 1.9-g progesterone-releasing device for 10 days; 2 mg oestradiol benzoate at insertion; 500 µg cloprostenol on day 7; and FTAI 48 h after device removal. Weight, age, expression of oestrus, sire, semen type (frozen sex-sorted or frozen conventional) and timing of insemination were examined for their relationship with first-service conception rates.

RESULTS

Heifers over 300 kg body weight were 1.18-fold more likely to express oestrus during the FTAI program. For every extra 1 kg, there was a 1.5% increase in the likelihood of expressing oestrus. First-service conception rates were 40.3% and 56.0% for sex-sorted and conventional semen, respectively, and were significantly higher when oestrus was expressed. The difference was greater for sex-sorted semen (3.4-fold) compared with conventional semen (1.5-fold). The interval from device removal to insemination varied between 47 and 51.4 h and had no significant effect on conception rates. However, there was a trend towards a higher conception rate for sex-sorted semen when inseminations were performed >50 h after device removal.

CONCLUSIONS

Increased fertility was associated with larger heifers and heifers that expressed oestrus, particularly when sexed-sorted semen was used. Variation in the timing of AI with respect to device removal between 47 and 51.4 h did not adversely affect conception rates.

This report offers the results of two experiments developed to test possible benefitial effects of the presence of corpus luteum (CL) on in vivo and in vitro sheep embryo production; using two different breeds treated with two different protocols by two different teams at two different centres. In the first trial, estrus was synchronized in 11 ewes with two doses of cloprostenol, 10 days apart. On day 1 after estimated ovulation, sheep were treated with progestagen sponges and superovulated with eight decreasing doses (26.4 units NIH-FSH-S1 x 3, 22.0 units x 2, and 17.6 units x 3) of ovine FSH injected twice daily. Ovulation rate and number of embryos obtained in vivo were compared to those from 12 control ewes without cloprostenol treatment. Presence of a CL improves the number of transferable embryos (7.4+/-0.6 versus 4.1+/-0.6 in control ewes, P < 0.05). The second trial investigated the effects of the presence of CL on embryos produced in vitro from six ewes bearing CL and six ewes without CL at start a superovulatory treatment consisting of 96 units of ovine FSH administered in four equal doses given every 12 h. There were not detected effects of the CL on the number and size of follicles or in the number, morphology and ability to resume meiosis of their oocytes. However, oocytes from ewes with CL showed higher rates of fertilization (73.5 versus 45.5%, P < 0.005), higher development to blastocyst (35.8 versus 19.3%, P < 0.01) and higher hatching rates after vitrification (80.0 versus 25.0%, P < 0.05).

Uncommon and controversial structures in cattle oocytes were studied in dominant and subordinate follicles of unstimulated Bos taurus and zebu (Bos indicus), and in FSH-stimulated B. taurus cattle, before or after administration of cloprostenol. Growing oocytes were very rare in follicles more than or equal to 5 mm in diameter. For the first time, special vesicles that may be involved in cortical granule synthesis were observed. Classical rough endoplasmic reticulum was very rare in unstimulated oocytes, but was seen at superovulation. Vacuolation of the nucleolus was a common feature in dominant oocytes that were collected after cloprostenol injection, except in superovulated cattle. Annulate lamellae were very rare or absent in oocytes of B. taurus, while they were more frequent in zebu oocytes.

Granulosa cells from follicles of different sizes from Booroola x Merino ewes which were homozygous (FF), heterozygous (F+) or non-carriers(++) of a fecundity gene were obtained 0-48 h after cloprostenol injection on Day 10 of the oestrous cycle. The highest mean amounts of cAMP produced by the cells did not differ between the genotypes. However, in the ++ ewes it was attained by cells from follicles greater than or equal to 5 mm in diameter, whereas in F+ and FF ewes it was attained by cells from follicles 3-4.5 mm in diameter. Cells from 1-2.5-mm diameter follicles of FF ewes were more sensitive to FSH and LH than were corresponding cells from F+ or ++ ewes. Granulosa cells from greater than or equal to 5 mm diameter follicles of ++ ewes 12-24 h after injection of cloprostenol had a lower mean response to FSH and LH than did cells obtained 0-6 or 36-48 h after cloprostenol. No such effect of time was evident for cells from any size of follicles obtained from F+ or FF ewes. In 1-2.5-mm diameter follicles, the mean aromatase activity of granulosa cells from ++ and F+ ewes was similar, but significantly lower than that of cells from FF ewes. In 3-4.5 mm diameter follicles, the mean aromatase activity of cells from F+ and FF ewes was similar, and significantly higher than that of cells from ++ ewes. For all 3 genotypes, there was a significant positive relationship between FSH or LH stimulation of granulosa cell cAMP production and cellular aromatase activity.

Two experiments were designed to determine whether pretreatment with Opticortenol (OPT), a long-acting corticosteroid, prior to induction of parturition with 25 mg of dexamethasone (DEX) alone or in combination with 500 mug cloprostenol (CLO) would result in a reduced incidence of retained placenta. In Experiment 1, 70% of the cows pretreated with 25 mg OPT on Day 270 of gestation calved before or within 24 hours of the scheduled induction treatment on Day 277. Cows induced to calve with DEX plus CLO without OPT pretreatment had an increased rate of placental retention (P<0.05), whereas, cows that received OPT were not different from the controls. In Experiment 2, cows received either 1 mg/25 kg OPT (high dosage) or 1 mg/50 kg OPT (low dosage) on Day 270 of gestation and were induced with DEX plus CLO on either Day 274 (4 days) or Day 276 (6 days). Cows claved 29.0 to 31.8 hours after induction treatment with 95% beginning to calve between 0700 and 1900 hours. The interval from calving to placental release and the incidence of retained placenta was not different between the high dosage 6-day group (29.4+/-8.2 hours, 29%) and the non-induced control cows (16.1+/-10.7 hours, 5%). When three cows in the high dosage 6-day group that retained their placentas for 30 to 36 hours were considered as not retained, the incidence of placental retention for that group was reduced still further to 17%. First service conception rates and pregnancy rates were lower in cows with retained placentas. Differences were significant (P<0.01) in Experiment 1 but not in Experiment 2. It was concluded that pretreatment with 1 mg/25 kg OPT 6 days prior to induction of parturition with DEX plus CLO in combination results in a predictable calving time, high calf viability, and a low incidence of placental retention.

Fifty-seven cycling buffalo cows of the river type were treated with two doses of 0.5 mg cloprostenol intramuscularly given 11 days apart. Each animal was inseminated twice at 72 and 96 hours after the second injection of cloprostenol. The first service conception rate diagnosed by rectal palpation at 90 days was 38.6 per cent. At the time of insemination the cervix was easily penetrable on both days in only 39 (68.4 per cent) of the animals. They were inseminated at or beyond the internal cervical os, while the others were inseminated in the cervical canal. There was a marked difference in conception rate between those receiving deep inseminations (48.7 per cent) and the others (16.7 per cent). In relation to the interval from calving to insemination the conception rates for those which had calved 60 to 90, 90 to 120 and 120 to 150 days earlier were 16.6, 36.4 and 55.5 per cent respectively. The use of cloprostenol treatment and fixed-time insemination is a useful method of overcoming the problem of oestrus detection in buffaloes. Acceptable levels of fertility can be obtained in those animals which have a sufficiently relaxed cervix to permit semen deposition at the internal os, provided the interval from calving to insemination is more than 90 days.

Using continuously observed primiparous cows, comparisons were made between cloprostenol-induced and preceding or succeeding spontaneous estruses in a crossover design. There were no significant differences between spontaneous and induced estruses in duration or intensity. In a second experiment, estrus was controlled by administration of two cloprostenol injections, 12 h apart, initiated at 0800 or 2000 h during the midluteal phase. Continuous observation and frequent blood sampling were used to determine relationships between behavior and plasma concentrations of LH and estradiol-17 beta. Relationships between plasma concentrations of estradiol-17 beta and the intensity or duration of estrous behavior were not detected. The intervals from treatment to the onset of estrus and to the LH surge were not affected by time of treatment but were highly correlated. The onset of the LH surge always followed the onset of standing to be mounted by 1 to 2 h. Initiating treatment with cloprostenol at 2000 h resulted in an increased proportion of animals exhibiting onset of estrus and increased mounting behavior at night relative to treatment at 0800 h. For efficient detection of estrus after cloprostenol treatment it is suggested that cloprostenol be administered early in the working day.

The objective of this study was to investigate whether butylated hydroxytoluene (BHT) could be used as a suitable supporter or alternative of egg yolk during preservation of goat spermatozoa. Three in vitro experiments and a fertility test were conducted to evaluate the effect of BHT on viability of chilled-stored semen as well as motility and kidding rate of frozen-thawed spermatozoa. In the first two experiments, ejaculates (n = 30/experiment) were collected from 10 bucks, split, diluted with egg yolk-based and egg yolk-free extenders supplemented with or without 0.3, 0.6, 2, 5 and 8 mM BHT and stored at 5 degrees C for 168 h. In the third experiment, 30 ejaculates were collected from the above-mentioned bucks, split and diluted with egg yolk-free extenders supplemented with or without 0.3, 0.6 and 0.9 mM BHT and egg yolk-based extenders supplemented with or without 5 mM BHT. Diluted semen was cooled to 5 degrees C over a period of 4 h, frozen and thawed in the form of 0.3-ml pellets. In the fertility test, 75 ejaculates were collected from two proven fertile bucks, split, diluted with egg yolk-free extenders containing 0.6 mm BHT and egg yolk-based extenders supplemented with or without 5 mM BHT, frozen and thawed as described above. An insemination volume of 0.6 ml containing 120-140 x 10(6) progressively motile spermatozoa was used for a single cervical insemination of cloprostenol-synchronized does (n = 230). The results showed that addition of 5 mM BHT to egg yolk-deficient (2.5%) extenders significantly improved viability of chilled-stored semen together with motility (48.5%) and fertility (62.5%) of frozen-thawed spermatozoa. Replacement of egg yolk in semen extenders by 0.6 mm BHT could sustain not only viability of chilled-stored semen but also post-thaw motility (47.5%) and fertility (53.75%) of frozen-thawed spermatozoa. In conclusion, supplementation of semen diluents with BHT can ameliorate preservability of goat sperm.

The aim of the study was to investigate the effect of Bovine Herpesvirus 4 (BoHV-4) and Histophilus (H.) somni on fertility rate of cows in a Hungarian Holstein-Friesian dairy herd with purulent vaginal discharge (PVD). Non-pregnant cows (n = 188) with mature corpus luteum were treated with cloprostenol and 3 days later if they did not show oestrus, were examined by rectal palpation. Animals showing PVD (n = 60/31.9%/) and 14 controls with normal vaginal discharge (Score 0) were randomly selected and further examined by ultrasonography and blood samples were collected for detecting BoHV-4 DNA and transcervical guarded swabs were collected from the uterus for bacteriological examination. Although the majority of the examined animals were infected with BoHV-4 and H. somni including the control animals as well, in group of animals with PVD score 3, fewer animals became pregnant and the duration between the first treatment to pregnancy was significantly extended. Based on these clinical and comparative data, our results confirm that these two microorganisms together may impair important reproductive parameters which may cause large economic losses to dairy farms.

The aim of this study was to evaluate the effectiveness of a protocol based on GnRH and PGF2α to synchronize the emergence of a new wave of ovarian follicular development in llamas and, therefore, when a new dominant follicle develops. Llamas (n = 18) were assigned to growing, mature or regressing follicle groups according to the phase of the follicular wave at the beginning of treatment. The protocol was initiated with a GnRH analogue (GnRHa) injection on Day 0 followed 7 days later with a d-cloprostenol injection and a second GnRHa injection on Day 10. Ovulation rate after the first GnRHa treatment, day of new follicle emergence, mean plasma progesterone concentration and percentage of animals with a newly developed dominant follicle ≥ 7 mm on Day 10 were evaluated. Ovulation rate after the first GnRHa was less in the regressing than mature and growing follicle groups and new follicular wave emergence occurred earlier in the regressing follicle group than in the other two groups. Mean plasma progesterone concentration in females that had ovulations after the first GnRHa injection was similar. The percentage of animals that had a new follicle ≥ 7 mm on Day 10 was not different among groups and the overall percentage was 66.6%. The total synchronization rate for development of a new wave of follicular development on Day 10 was greater in females having ovulations after the first GnRHa injection than in those that did not have ovulations. In conclusion, the protocol used in the present study was useful for synchronizing ovarian follicular development in 66% of the llamas regardless of the phase of the follicular wave development at the beginning of treatment.

The aim of the present study was to evaluate the susceptibility of the corpus luteum to d-cloprostenol (synthetic analog of PGF(2α)) throughout the luteal phase in llamas. Female llamas (n=43) were induced to ovulate by GnRH injection in the presence of an ovulatory follicle and randomly assigned into one of six groups: control and treated with an injection of d-cloprostenol on Day 3, 4, 5, 6 or 8 post GnRH. Blood samples were collected to determine plasma progesterone concentrations. There was no effect of treatment on animals injected on Day 3 or 4 post-GnRH. In animals treated on Day 5, different responses were observed. No effect of treatment was recorded in 27% of the animals whereas 55% of the llamas showed a transitory decrease followed by a recovery in plasma progesterone concentrations after d-cloprostenol injection, indicative of a resurgence of the corpus luteum, extending the luteal phase a day more than in control animals. In the remaining 18% of the animals injected on Day 5, (corresponding to those exhibiting the greatest plasma progesterone concentrations at the day of injection), complete luteolysis was observed. Plasma progesterone concentrations decreased to below 1 ng ml(-1) 24 h after d-cloprostenol in llamas injected on Day 6 or 8 post-GnRH. In conclusion, the corpus luteum of llamas is completely refractory to PGF(2α) until Day 4 after induction of ovulation, being partially sensitive by Day 5 and fully responsive to PGF(2α), by Day 6 after induction of ovulation.

Seven dairy cattle showing clinical post partum endometritis were monitored daily by rectal examination of uterus, ovaries and vagina and by sampling of jugular venous blood and uterine pus. The animals were treated by intramuscular injection of 500 microgram cloprostenol (ICI). All seven animals had an immediate reduction of plasma progesterone concentrations and showed oestrus within two to three days. In six cases the clinical endometritis resolved, with uterine involution, within seven days and uterine mucus sample showed no specific growth. One animal required a second cloprostenol injection 11 days after the first to achieve complete resolution. Subsequently, plasma progesterone levels rose in all animals but two cases later appeared to become anoestrous, perhaps due to pituitary insufficiency. In a further study of chronic endometritis in cattle in the field, 51 out of 56 animals treated in the presence of a corpus luteum showed oestrus within 14 days with resolution of the condition; five others did not respond. None of the three cases which had been treated in the absence of a corpus luteum showed any improvement. This lack of response was not unexpected and supports the view that the mode of action of cloprostenol in this treatment regime is to induce luteolysis. The mechanism of therapy and possible explanation for the occurrence of chronic endometritis are discussed.

Changes in perineal odor as estrus is approached could form the basis of a new method of estrus detection. Perineal odor of cyclic cows was monitored. Estrus was identified using ovarian ultrasound, behavioral observations, and plasma assay for progesterone and estradiol. Samples were taken from the dorsal lateral perineal (perivulval) area using cotton bud swabs and presented to an electronic nose. Twelve conducting polymer sensors were used to quantify odor in terms of a change in sensor resistance. Preliminary data (Experiment 1) indicate that the odor signals between the luteal phase and estrus could be distinguished for a group of five cows. In Experiment 2, samples were obtained daily from eight cows during the midluteal phase and from d -2 to d 8 of the cycle (d 0 = day of estrus, induced using cloprostenol). Seven of the eight cows cycled normally. Of the 12 sensors, 7 showed a significant change in resistance that was dependent on the day of the estrous cycle. Basal values were those taken in the luteal phase; values peaked on d -1, rose transiently on d 3, and returned to baseline on d 5 to 6. This pattern is strongly correlated with plasma estradiol concentration. The use of artificial olfaction could enable more accurate detection of estrus and has the potential to increase fertility in cows.