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Brownhills, United Kingdom

Cuervo-Arango J.,CEU Cardenal Herrera University | Newcombe J.R.,Equine Fertility Clinic
Reproduction in Domestic Animals | Year: 2010

Prostaglandin F 2α and its analogues (PGF) are widely used in equine reproductive practice. The interval from PGF treatment to ovulation (ITO) varies greatly with a range from 2 to 16 days. Clinical observation suggests that mares mated and ovulated soon after PGF treatment may have poor fertility. Reproductive records of 329 cyclic Thoroughbred mares were analysed retrospectively. The following parameters were analysed: (i) use of cloprostenol; (ii) ITO and (iii) number of ovulations per cycle. According to these parameters, mares were classified into four groups. (i) mares with spontaneous ovulations, n = 57; (ii) mares induced with cloprostenol and ITO = 4-7 days, n = 77; (iii) ITO = 8-10 days, n = 89 and (iv) ITO = ≥11 days, n = 106. Differences in pregnancy (PR) and multiple ovulation (MO) rates among groups were tested using chi-squared test. PR rates for groups 1-4 were: 73.7%, 46.7%, 64% and 71.7% respectively (p < 0.05). Groups 1 and 2 had lower (p < 0.05) MO rate (24.6% and 20.8%) than groups 3 and 4 (40.4% and 44.3%). It appears that ovulation soon after PGF-induced luteolysis is detrimental to PR rates. It was found highly significant that in cloprostenol-treated mares, the MO rate was enhanced without subsequent increase in multiple pregnancies. © 2009 Blackwell Verlag GmbH. Source


Davies Morel M.C.G.,Aberystwyth University | Newcombe J.R.,Equine Fertility Clinic | Hayward K.,Aberystwyth University
Theriogenology | Year: 2010

The importance of elucidating factors affecting reproductive performance and efficiency is of paramount concern to the equine industry. Oocyte viability is known to be one of the determinants of reproductive success and evidence suggests that it may be linked to follicle size. The aims of this study were, therefore, to ascertain: i) the average diameter and range of pre-ovulatory follicles in Thoroughbred mares; ii) whether this is affected by either mare age, time within the breeding season, or the presence of multiple pre-ovulatory follicles (MO). One thousand, four hundred and ninety two Thoroughbred mares, aged 2-26 years, were examined with ultrasound to ascertain ovulation date to within 24h, and pre-ovulatory follicle(s) (F1) diameter. Mares were divided into groups according to age (7 groups, 2-4 yr, 5-7 yr, 8-10 yr, 11-13 yr, 14-16 yr, 17-19 yr, >19 yr), time within the season (16 half-month groups, from Feb 1st to Sept 30th), and pre-ovulatory follicles (single, {SO} or multiple {MO}). Overall average F1 diameter was 39.95 ± 4.84 mm (range 22-50 mm). Mare age had a significant (P < 0.001) negative effect on F1 diameter (largest F1 38.95 ± 5.61 mm, mares 2-4 yrs; smallest F1 33.30 ± 4.66 mm, mares >19 yrs) as did season (largest F1 44.20 ± 3.95 mm, Feb 1st-14th; smallest F1 33.74 ± 4.87 mm, Aug 15th-31st) and the presence of more than one pre-ovulatory follicle (MO F1 35.45 ± 4.53 mm; SO F1 37.44 ± 4.84 mm). In conclusion older mares, bred towards the end of the breeding season, especially if MO were present, were more likely to ovulate from smaller follicles. If, as suggested, small pre-ovulatory follicle size is associated with low oocyte viability, then this may account, at least in part, for the poor fertility rates characteristic of older MO mares, bred later in the season and so justify increased monitoring and careful reproductive management of such mares. © 2010 Elsevier Inc. Source


Newcombe J.R.,Equine Fertility Clinic | Paccamonti D.,Louisiana State University | Cuervo-Arango J.,CEU Cardenal Herrera University
Animal Reproduction Science | Year: 2011

Data were analysed retrospectively from fourteen breeding seasons at an Equine Fertility Clinic for the effect of interval between pre- and postovulatory examinations for immediate postovulatory insemination on pregnancy rate (PR) and embryo loss rate (ELR). Mares of various breeds and ages were examined at intervals which varied from 0.5 to 15 h between the pre- and postovulatory period over 867 cycles. When ovulation was detected they were inseminated with a single dose of commercial frozen-thawed semen. All mares were treated in the post-insemination period with intrauterine antibiotics and then with oxytocin. Pregnancy diagnoses were made at 12-17 days post-ovulation and at intervals up to 40 days. The overall PR was 47.9%. The data were pooled into 3 h examination intervals. In the first interval, mares were inseminated at the time of ovulation to 3 h post-ovulation (n= 44) with a PR of 43.2%. Results of insemination to consecutive 3 h intervals gave PR of 44.7% (3-6 h, n= 150), 45.1% (6-9 h, n= 432), 55.8% (9-12 h, n= 190) and 54.9% (12-15 h, n= 51). ELR was 10.5%, 11.9%, 5.6%, 7.5% and 3.6% respectively for the same intervals. There was no statistical difference in either the PR or ELR. It is concluded that in a postovulatory insemination regime with routine post-insemination treatment as described, examination of mares at intervals of any less than 12-15 h does not improve pregnancy or embryo loss rates. © 2010 Elsevier B.V. Source


Davies Morel M.C.G.,Aberystwyth University | Newcombe J.R.,Equine Fertility Clinic | Lauber M.,Aberystwyth University
Veterinary Journal | Year: 2012

To determine whether manually reduced multiple pregnancies (MPs) are at a greater risk of pregnancy loss than single pregnancy (SP) in mares, and to examine if a difference exists in the timing of pregnancy loss between manually reduced MPs and SPs, 1916 Thoroughbred mares were ultrasonically monitored every 2. days during oestrus to confirm ovulation, and up to Day 40 post-ovulation to confirm pregnancy. Ultimate pregnancy outcome was ascertained from the General Thoroughbred Stud book and classified as live foal (LF), early abortion (EA; Days 40-150), slipped foal (SF; Days 150-term), and barren (B; Time of pregnancy loss unknown).Significantly (P< 0.05) more SPs failed (17.23%; 226/1312) than manually reduced MPs (13.41%; 81/604). Both SPs and MPs were at greatest risk of being lost as EA (72.16%; 127/176 and 61.67%; 37/60, respectively) compared to SF (27.84%; 49/176 and 38.33%; 23/60). There was no significant difference in the time of greatest risk of pregnancy loss between manually reduced MPs and SPs. It was concluded that owners and veterinarians can be assured that manual reduction of MPs does not increase the risk of pregnancy loss above those associated with SPs. © 2011 Elsevier Ltd. Source


Newcombe J.,Equine Fertility Clinic | Cuervo-Arango J.,CEU Cardenal Herrera University
Reproduction in Domestic Animals | Year: 2011

Contents: One hundred and fifty-four mares were inseminated with fresh semen either during the pre- or post-ovulatory periods at different intervals relative to ovulation: 36-24h (n=17) and 24-0h (n=30) before ovulation; 0-8h (n=21), 8-16h (n=24), 16-24h (n=48) and 24-32h (n=14) h after ovulation. All mares received the same routine post-mating treatment consisting of an intrauterine infusion with 1litre of saline and antibiotics followed 8h later by an intravenous administration of oxytocin. Artificial inseminations (AI) from 36h before ovulation up to 16h post-ovulation were performed with transported cooled semen. While there was no data available for inseminations later than 16h, data from natural mating after 16h post-ovulation were included. Pregnancy rate (PR) of mares inseminated 36-24h (29.4%) was significantly lower (p<0.05) than mares inseminated 24-0h before ovulation (60%), 0-8h (66.7%) and 8-16h (70.1%) post-ovulation. Embryo loss rate (ELR) was highest in mares mated 24-32h after ovulation (75%). PR of mares mated 16-24h post-ovulation (54.1%) did not differ significantly from any other group (p>0.05); however, the ELR did increased markedly (34.6%) compared with inseminations before 16h post-ovulation (<12%). At ≥30days post-ovulation, PR of mares mated 16-24h after ovulation (35.4%) was significantly lower than mares mated 0-16h after ovulation (62%). Good PR with acceptable ELR can result from inseminations within 16h of ovulation, at least with this specific post-mating routine treatment. © 2010 Blackwell Verlag GmbH. Source

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